Debian Contributions: 2024-09 Contributing to Debian is part of Freexian s mission. This article covers the latest achievements of Freexian and their collaborators. All of this is made possible by organizations subscribing to our Long Term Support contracts and consulting services.

Pydantic v2, by Colin Watson Pydantic is a useful library for validating data in Python using type hints: Freexian uses it in a number of projects, including Debusine. Its Debian packaging had been stalled at 1.10.17 in testing for some time, partly due to needing to make sure everything else could cope with the breaking changes introduced in 2.x, but mostly due to needing to sort out packaging of its new Rust dependencies. Several other people (notably Alexandre Detiste, Andreas Tille, Drew Parsons, and Timo R hling) had made some good progress on this, but nobody had quite got it over the line and it seemed a bit stuck. Colin upgraded a few Rust libraries to new upstream versions, packaged rust-jiter, and chased various failures in other packages. This eventually allowed getting current versions of both pydantic-core and pydantic into testing. It should now be much easier for us to stay up to date routinely.

Reworking of glib2.0 for cross bootstrap, by Helmut Grohne Simon McVittie (not affiliated with Freexian) earlier restructured the libglib2.0-dev such that it would absorb more functionality and in particular provide tools for working with .gir files. Those tools practically require being run for their host architecture (practically this means running under qemu-user) which is at odds with the requirements of architecture cross bootstrap. The qemu requirement was expressed in package dependencies and also made people unhappy attempting to use libglib2.0-dev for i386 on amd64 without resorting to qemu. The use of qemu in architecture bootstrap is particularly problematic as it tends to not be ready at the time bootstrapping is needed. As a result, Simon proposed and implemented the introduction of a libgio-2.0-dev package providing a subset of libglib2.0-dev that does not require qemu. Packages should continue to use libglib2.0-dev in their Build-Depends unless involved in architecture bootstrap. Helmut reviewed and tested the implementation and integrated the necessary changes into rebootstrap. He also prepared a patch for libverto to use the new package and proposed adding forward compatibility to glib2.0. Helmut continued working on adding cross-exe-wrapper to architecture-properties and implemented autopkgtests later improved by Simon. The cross-exe-wrapper package now provides a generic mechanism to a program on a different architecture by using qemu when needed only. For instance, a dependency on cross-exe-wrapper:i386 provides a i686-linux-gnu-cross-exe-wrapper program that can be used to wrap an ELF executable for the i386 architecture. When installed on amd64 or i386 it will skip installing or running qemu, but for other architectures qemu will be used automatically. This facility can be used to support cross building with targeted use of qemu in cases where running host code is unavoidable as is the case for GObject introspection. This concludes the joint work with Simon and Niels Thykier on glib2.0 and architecture-properties resolving known architecture bootstrap regressions arising from the glib2.0 refactoring earlier this year.

Analyzing binary package metadata, by Helmut Grohne As Guillem Jover (not affiliated with Freexian) continues to work on adding metadata tracking to dpkg, the question arises how this affects existing packages. The dedup.debian.net infrastructure provides an easy playground to answer such questions, so Helmut gathered file metadata from all binary packages in unstable and performed an explorative analysis. Some results include:

• binutils-mipsen uses wrong file ownership
• /usr-merge is not the only cause for aliasing problems in Debian.
  • mediawiki vs vistrails
  • bmake vs ros-mk
  • golang-github-eapache-go-resiliency-dev vs golang-gopkg-eapache-go-resiliency.v1-dev
  • node-markdown-it vs libjs-markdown-it
  • dokuwiki vs php-phpseclib
  • dokuwiki vs php-random-compat

Guillem also performed a cursory analysis and reported other problem categories such as mismatching directory permissions for directories installed by multiple packages and thus gained a better understanding of what consistency checks dpkg can enforce.

Python archive rebuilds, by Stefano Rivera Last month Stefano started to write some tooling to do large-scale rebuilds in debusine, starting with finding packages that had already started to fail to build from source (FTBFS) due to the removal of setup.py test. This month, Stefano did some more rebuilds, starting with experimental versions of dh-python. During the Python 3.12 transition, we had added a dependency on python3-setuptools to dh-python, to ease the transition. Python 3.12 removed distutils from the stdlib, but many packages were expecting it to still be available. Setuptools contains a version of distutils, and dh-python was a convenient place to depend on setuptools for most package builds. This dependency was never meant to be permanent. A rebuild without it resulted in mass-filing about 340 bugs (and around 80 more by mistake). A new feature in Python 3.12, was to have unittest s test runner exit with a non-zero return code, if no tests were run. We added this feature, to be able to detect tests that are not being discovered, by mistake. We are ignoring this failure, as we wouldn t want to suddenly cause hundreds of packages to fail to build, if they have no tests. Stefano did a rebuild to see how many packages were affected, and found that around 1000 were. The Debian Python community has not come to a conclusion on how to move forward with this. As soon as Python 3.13 release candidate 2 was available, Stefano did a rebuild of the Python packages in the archive against it. This was a more complex rebuild than the others, as it had to be done in stages. Many packages need other Python packages at build time, typically to run tests. So transitions like this involve some manual bootstrapping, followed by several rounds of builds. Not all packages could be tested, as not all their dependencies support 3.13 yet. The result was around 100 bugs in packages that need work to support Python 3.13. Many other packages will need additional work to properly support Python 3.13, but being able to build (and run tests) is an important first step.

Miscellaneous contributions

• Carles prepared the update of python-pyaarlo package to a new upstream release.
• Carles worked on updating python-ring-doorbell to a new upstream release. Unfinished, pending to package a new dependency python3-firebase-messaging RFP #1082958 and its dependency python3-http-ece RFP #1083020.
• Carles improved po-debconf-manager. Main new feature is that it can open Salsa merge requests. Aiming for a lightning talk in MiniDebConf Toulouse (November) to be functional end to end and get feedback from the wider public for this proof of concept.
• Carles helped one translator to use po-debconf-manager (added compatibility for bullseye, fixed other issues) and reviewed 17 package templates.
• Colin upgraded the OpenSSH packaging to 9.9p1.
• Colin upgraded the various YubiHSM packages to new upstream versions, enabled more tests, fixed yubihsm-shell build failures on some 32-bit architectures, made yubihsm-shell build reproducibly, and fixed yubihsm-connector to apply udev rules to existing devices when the package is installed. As usual, bookworm-backports is up to date with all these changes.
• Colin fixed quite a bit of fallout from setuptools 72.0.0 removing setup.py test, backported a large upstream patch set to make buildbot work with SQLAlchemy 2.0, and upgraded 25 other Python packages to new upstream versions.
• Enrico worked with Jakob Haufe to get him up to speed for managing sso.debian.org
• Rapha l did remove spam entries in the list of teams on tracker.debian.org (see #1080446), and he applied a few external contributions, fixing a rendering issue and replacing the DDPO link with a more useful alternative. He also gave feedback on a couple of merge requests that required more work. As part of the analysis of the underlying problem, he suggested to the ftpmasters (via #1083068) to auto-reject packages having the too-many-contacts lintian error, and he raised the severity of #1076048 to serious to actually have that 4 year old bug fixed.
• Rapha l uploaded zim and hamster-time-tracker to fix issues with Python 3.12 getting rid of setuptools. He also uploaded a new gnome-shell-extension-hamster to cope with the upcoming transition to GNOME 47.
• Helmut sent seven patches and sponsored one upload for cross build failures.
• Helmut uploaded a Nagios/Icinga plugin check-smart-attributes for monitoring the health of physical disks.
• Helmut collaborated on sbuild reviewing and improving a MR for refactoring the unshare backend.
• Helmut sent a patch fixing coinstallability of gcc-defaults.
• Helmut continued to monitor the evolution of the /usr-move. With more and more key packages such as libvirt or fuse3 fixed. We re moving into the boring long-tail of the transition.
• Helmut proposed updating the meson buildsystem in debhelper to use env2mfile.
• Helmut continued to update patches maintained in rebootstrap. Due to the work on glib2.0 above, rebootstrap moves a lot further, but still fails for any architecture.
• Santiago reviewed some Merge Request in Salsa CI, such as: !478, proposed by Otto to extend the information about how to use additional runners in the pipeline and !518, proposed by Ahmed to add support for Ubuntu images, that will help to test how some debian packages, including the complex MariaDB are built on Ubuntu. Santiago also prepared !545, which will make the reprotest job more consistent with the result seen on reproducible-builds.
• Santiago worked on different tasks related to DebConf 25. Especially he drafted the fundraising brochure (which is almost ready).
• Thorsten Alteholz uploaded package libcupsfilter to fix the autopkgtest and a dependency problem of this package. After package splix was abandoned by upstream and OpenPrinting.org adopted its maintenance, Thorsten uploaded their first release.
• Anupa published posts on the Debian Administrators group in LinkedIn and moderated the group, one of the tasks of the Debian Publicity Team.
• Anupa helped organize DebUtsav 2024. It had over 100 attendees with hand-on sessions on making initial contributions to Linux Kernel, Debian packaging, submitting documentation to Debian wiki and assisting Debian Installations.

Welcome to the September 2024 report from the Reproducible Builds project! Our reports attempt to outline what we ve been up to over the past month, highlighting news items from elsewhere in tech where they are related. As ever, if you are interested in contributing to the project, please visit our Contribute page on our website. Table of contents:

1. New binsider tool to analyse ELF binaries
2. Unreproducibility of GHC Haskell compiler 95% fixed
3. Mailing list summary
4. Towards a 100% bit-for-bit reproducible OS
5. Two new reproducibility-related academic papers
6. Distribution work
7. diffoscope
8. Other software development
9. Android toolchain core count issue reported
10. New Gradle plugin for reproducibility
11. Website updates
12. Upstream patches
13. Reproducibility testing framework

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New binsider tool to analyse ELF binaries Reproducible Builds developer Orhun Parmaks z has announced a fantastic new tool to analyse the contents of ELF binaries. According to the project s README page:

Binsider can perform static and dynamic analysis, inspect strings, examine linked libraries, and perform hexdumps, all within a user-friendly terminal user interface!

More information about Binsider s features and how it works can be found within Binsider s documentation pages.

Unreproducibility of GHC Haskell compiler 95% fixed A seven-year-old bug about the nondeterminism of object code generated by the Glasgow Haskell Compiler (GHC) received a recent update, consisting of Rodrigo Mesquita noting that the issue is:

95% fixed by [merge request] !12680 when -fobject-determinism is enabled. [ ]

The linked merge request has since been merged, and Rodrigo goes on to say that:

After that patch is merged, there are some rarer bugs in both interface file determinism (eg. #25170) and in object determinism (eg. #25269) that need to be taken care of, but the great majority of the work needed to get there should have been merged already. When merged, I think we should close this one in favour of the more specific determinism issues like the two linked above.

Mailing list summary On our mailing list this month:

• Fay Stegerman let everyone know that she started a thread on the Fediverse about the problems caused by unreproducible zlib/deflate compression in .zip and .apk files and later followed up with the results of her subsequent investigation.
• Long-time developer kpcyrd wrote that there has been a recent public discussion on the Arch Linux GitLab [instance] about the challenges and possible opportunities for making the Linux kernel package reproducible , all relating to the CONFIG_MODULE_SIG flag. [ ]
• Bernhard M. Wiedemann followed-up to an in-person conversation at our recent Hamburg 2024 summit on the potential presence for Reproducible Builds in recognised standards. [ ]
• Fay Stegerman also wrote about her worry about the possible repercussions for RB tooling of Debian migrating from zlib to zlib-ng as reproducibility requires identical compressed data streams. [ ]
• Martin Monperrus wrote the list announcing the latest release of maven-lockfile that is designed aid building Maven projects with integrity . [ ]
• Lastly, Bernhard M. Wiedemann wrote about potential role of reproducible builds in combatting silent data corruption, as detailed in a recent Tweet and scholarly paper on faulty CPU cores. [ ]

Towards a 100% bit-for-bit reproducible OS Bernhard M. Wiedemann began writing on journey towards a 100% bit-for-bit reproducible operating system on the openSUSE wiki:

This is a report of Part 1 of my journey: building 100% bit-reproducible packages for every package that makes up [openSUSE s] minimalVM image. This target was chosen as the smallest useful result/artifact. The larger package-sets get, the more disk-space and build-power is required to build/verify all of them.

This work was sponsored by NLnet s NGI Zero fund.

Two new reproducibility-related academic papers Marvin Strangfeld published his bachelor thesis, Reproducibility of Computational Environments for Software Development from RWTH Aachen University. The author offers a more precise theoretical definition of computational environments compared to previous definitions, which can be applied to describe real-world computational environments. Additionally, Marvin provide a definition of reproducibility in computational environments, enabling discussions about the extent to which an environment can be made reproducible. The thesis is available to browse or download in PDF format. In addition, Shenyu Zheng, Bram Adams and Ahmed E. Hassan of Queen s University, ON, Canada have published an article on hermeticity in Bazel-based build systems:

A hermetic build system manages its own build dependencies, isolated from the host file system, thereby securing the build process. Although, in recent years, new artifact-based build technologies like Bazel offer build hermeticity as a core functionality, no empirical study has evaluated how effectively these new build technologies achieve build hermeticity. This paper studies 2,439 non-hermetic build dependency packages of 70 Bazel-using open-source projects by analyzing 150 million Linux system file calls collected in their build processes. We found that none of the studied projects has a completely hermetic build process, largely due to the use of non-hermetic top-level toolchains. [ ]

Distribution work In Debian this month, 14 reviews of Debian packages were added, 12 were updated and 20 were removed, all adding to our knowledge about identified issues. A number of issue types were updated as well. [ ][ ] In addition, Holger opened 4 bugs against the debrebuild component of the devscripts suite of tools. In particular:

• #1081047: Fails to download .dsc file.
• #1081048: Does not work with a proxy.
• #1081050: Fails to create a debrebuild.tar.
• #1081839: Fails with E: mmdebstrap failed to run error.

Last month, an issue was filed to update the Salsa CI pipeline (used by 1,000s of Debian packages) to no longer test for reproducibility with reprotest s build_path variation. Holger Levsen provided a rationale for this change in the issue, which has already been made to the tests being performed by tests.reproducible-builds.org. This month, this issue was closed by Santiago R. R., nicely explaining that build path variation is no longer the default, and, if desired, how developers may enable it again. In openSUSE news, Bernhard M. Wiedemann published another report for that distribution.

diffoscope diffoscope is our in-depth and content-aware diff utility that can locate and diagnose reproducibility issues. This month, Chris Lamb made the following changes, including preparing and uploading version 278 to Debian:

• New features:
  • Add a helpful contextual message to the output if comparing Debian .orig tarballs within .dsc files without the ability to fuzzy-match away the leading directory. [ ]
• Bug fixes:
  • Drop removal of calculated os.path.basename from GNU readelf output. [ ]
  • Correctly invert X% similar value and do not emit 100% similar . [ ]
• Misc:
  • Temporarily remove procyon-decompiler from Build-Depends as it was removed from testing (via #1057532). (#1082636)
  • Update copyright years. [ ]

For trydiffoscope, the command-line client for the web-based version of diffoscope, Chris Lamb also:

• Added an explicit python3-setuptools dependency. (#1080825)
• Bumped the Standards-Version to 4.7.0. [ ]

Other software development disorderfs is our FUSE-based filesystem that deliberately introduces non-determinism into system calls to reliably flush out reproducibility issues. This month, version 0.5.11-4 was uploaded to Debian unstable by Holger Levsen making the following changes:

• Replace build-dependency on the obsolete pkg-config package with one on pkgconf, following a Lintian check. [ ]
• Bump Standards-Version field to 4.7.0, with no related changes needed. [ ]

In addition, reprotest is our tool for building the same source code twice in different environments and then checking the binaries produced by each build for any differences. This month, version 0.7.28 was uploaded to Debian unstable by Holger Levsen including a change by Jelle van der Waa to move away from the pipes Python module to shlex, as the former will be removed in Python version 3.13 [ ].

Android toolchain core count issue reported Fay Stegerman reported an issue with the Android toolchain where a part of the build system generates a different classes.dex file (and thus a different .apk) depending on the number of cores available during the build, thereby breaking Reproducible Builds:

We ve rebuilt [tag v3.6.1] multiple times (each time in a fresh container): with 2, 4, 6, 8, and 16 cores available, respectively:

• With 2 and 4 cores we always get an unsigned APK with SHA-256 14763d682c9286ef .
• With 6, 8, and 16 cores we get an unsigned APK with SHA-256 35324ba4c492760 instead.

New Gradle plugin for reproducibility A new plugin for the Gradle build tool for Java has been released. This easily-enabled plugin results in:

reproducibility settings [being] applied to some of Gradle s built-in tasks that should really be the default. Compatible with Java 8 and Gradle 8.3 or later.

Website updates There were a rather substantial number of improvements made to our website this month, including:

• Chris Lamb:
  • Attempt to use GitLab CI to artifact the website; hopefully useful for testing branches. [ ]
  • Correct the linting rule whilst building the website. [ ]
  • Make a number of small changes to Kees post written by Vagrant. [ ][ ][ ]
  • Add the Civil Infrastructure Platform to the Projects page. [ ]
  • Miscellaneous administration of misfiled images. [ ][ ]
• Evangelos Tzaras made a huge number of changes related to the recent Hamburg 2024 summit [ ][ ][ ][ ][ ] as well as proposed an infographic about which question Reproducible Builds is trying to answer.
• Holger Levsen added his two presentations (Reproducible Builds: The First Eleven Years and Preserving *other* build artifacts) to the website. [ ]
• Jelle van der Waa completely modernised the System Images documentation, noting that a lot has changed since 2017(!); ext4, erofs and FAT filesystems can now be made reproducible . [ ]
• Developer RyanSquared replaced the continuous integration test link for Arch Linux on our Projects page with an external instance [ ][ ] as well as updated the documentation to reflect the dependencies required to build the website [ ].
• Vagrant Cascadian pushed a lengthy interview with Linux developer Kees Cook. [ ][ ][ ][ ]

Upstream patches The Reproducible Builds project detects, dissects and attempts to fix as many currently-unreproducible packages as possible. We endeavour to send all of our patches upstream where appropriate. This month, we wrote a large number of such patches, including:

• Bernhard M. Wiedemann:
  • agama-integration-tests (random)
  • contrast (FTBFS-nocheck)
  • cpython (FTBFS-2038)
  • crash (parallelism, race)
  • ghostscript (toolchain date)
  • glycin-loaders (FTBFS -j1)
  • gstreamer-plugins-rs (date, other)
  • kernel-doc/Sphinx (toolchain bug, parallelism/race)
  • kernel (parallelism in BTF)
  • libcamera (random key)
  • libgtop (uname -r)
  • libsamplerate (random temporary directory)
  • lua-luarepl (FTBFS)
  • meson (toolchain)
  • netty (modification time in .a)
  • nvidia-persistenced (date)
  • nvidia-xconfig (date-related issue)
  • obs-build (build-tooling corruption)
  • perl (Perl records kernel version)
  • pinentry (make efl droppable)
  • python-PyGithub (FTBFS 2024-11-25)
  • python-Sphinx (parallelism/race)
  • python-chroma-hnswlib (CPU)
  • python-libcst
  • python-pygraphviz (random timing)
  • python312 (.pyc embeds modification time)
  • python312 (drop .pyc from documentation time)
  • scap-security-guide (date)
  • seahorse (parallelism)
  • subversion (minor Java .jar modification times)
  • xen/acpica (date-related issue in toolchain)
  • xmvn (random)
• Fridrich Strba:
  • ant (jar mtime)
  • xmvn (various fixes)
• Chris Lamb:
  • #1082702 filed against magic-wormhole-transit-relay.
  • #1082706 filed against python-sphobjinv.
  • #1082707 filed against lomiri-content-hub.
  • #1082796 filed against python-mt-940.
  • #1082806 filed against tree-puzzle.
  • #1083053 filed against muon-meson.
• James Addison:
  • guake (fix a parallelism/timing-race build bug)
  • sphobjinv (duplicates fix from Debian bug #1082706)

Reproducibility testing framework The Reproducible Builds project operates a comprehensive testing framework running primarily at tests.reproducible-builds.org in order to check packages and other artifacts for reproducibility. In September, a number of changes were made by Holger Levsen, including:

• Debian-related changes:
  • Upgrade the osuosl4 node to Debian trixie in anticipation of running debrebuild and rebuilderd there. [ ][ ][ ]
  • Temporarily mark the osuosl4 node as offline due to ongoing xfs_repair filesystem maintenance. [ ][ ]
  • Do not warn about (very old) broken nodes. [ ]
  • Add the risc64 architecture to the multiarch version skew tests for Debian trixie and sid. [ ][ ][ ]
  • Mark the virt 32,64 b nodes as down. [ ]
• Misc changes:
  • Add support for powercycling OpenStack instances. [ ]
  • Update the fail2ban to ban hosts for 4 weeks in total [ ][ ] and take care to never ban our own Jenkins instance. [ ]

In addition, Vagrant Cascadian recorded a disk failure for the virt32b and virt64b nodes [ ], performed some maintenance of the cbxi4a node [ ][ ] and marked most armhf architecture systems as being back online.

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Finally, If you are interested in contributing to the Reproducible Builds project, please visit our Contribute page on our website. However, you can get in touch with us via:

• IRC: #reproducible-builds on irc.oftc.net.
• Mastodon: @reproducible_builds@fosstodon.org
• Mailing list: rb-general@lists.reproducible-builds.org
• Twitter: @ReproBuilds

Another short status update of what happened on my side last month. Besides the usual amount of housekeeping last month was a lot about getting old issues resolved by finishing some stale merge requests and work in pogress MRs. I also pushed out the Phosh 0.42.0 Release phosh

• Mark mobile-data quick setting as insensitive when modem is off (MR)
• Document handler naming (MR)
• Phosh 0.41.1 (MR)
• Phosh 0.42~rc1 (MR)
• Phosh 0.42.0 (MR)
• Handle per app notification enable setting (MR) (a 3y old MR cleaned up and out of the way)
• Use parent's icon if child doesn't have one (MR (another 1y old MR moved out of draft status)
• Fix Rust build and upcoming events .plugin file (MR)
• Lint markdown (MR)
• Sanitize versions as this otherwise breaks the libphosh-rs build (MR)
• lockscreen: Swap deck and carousel to avoid triggering the plugins page when entering pin and let the lockscreen shrink to smaller sizes (MR) (two more year old usability issues out of the way)
• Let bitfield values end up in the docs again (MR)
• Don't focus incorrect app on launch (MR). This could happen with apps like calls that run a daemon (and needs more work for a clean solution).
• Continue with wallpaper MR (MR) (still draft)
• Brush up and land an old MR to avoid crashes on scale changes (MR). Another five month old MR out of the way.
• API version the shared library (MR)
• Ensure we send enough feedback when phone is blanked/locked (MR). This should be way easier now for apps as they don't need to do anything and we can avoid duplicate feedback sent from e.g. Chatty.
• Fix possible use after free when activating notifications on the lock screen (MR)

phoc

• Simplify layer-surface creation / destruction (MR)
• Don't lose preedit when switching applications, opening menus, etc (MR). This fixes the case (e.g. with word completion in phosh-osk-stub enabled) where it looks to the user as if the last typed word would get lost when switching from a text editor to another app or when opening a menu
• Ease focus debugging (MR)
• Release 0.42~rc1 (MR)
• Release 0.42.0 (MR)
• Mention examples in docs and check more things (MR)

phosh-mobile-settings

• Release 0.42~rc1 (MR)
• Release 0.42 (MR)
• Update ci-fairy (MR)

libphosh-rs

• Update Phosh-0.gir with above phosh fixes to unbreak the build (MR)
• Rework to work with API versioned libphosh (MR)

phosh-osk-stub

• Add paste button to easy pasting text (MR)
• Add copy button (draft) (MR)
• Fix word salad with presage completer when entering cursor navigation mode (and in some other cases) (MR 1). Presage has the best completion but was marked experimental due to that.
• Submit preedit on changes to terminal and emoji layout (MR)
• Enable hint based completion by default (MR)
• Release 0.42~r1 (MR)
• Release 0.42.0 (MR)

phosh-wallpapers

• Add sound for cellbroadcast (MR)
• Release 0.42.0 (MR)

meta-phosh

• Weekly image builds of nightly packages are now built in CI and uploaded.
• Handle Fixes: tag in git commit messages as well (MR)
• Let release prep handle non-RC versions as well (MR)
• Add common markdown linter job (MR)

Debian

• Update wlr-randr (MR)
• Upload libqmi developement snapshot (MR) (Helps eSIM and CellBroadcast)
• Update phosh to not crash with GSD from GNOME 47 (MR)
• Fix systemd unit path in calls (MR)
• Package wikietractor (MR)

ModemManager

• More work on Cell Broadcast so we can finally undraft (MR)

Calls

• Check consistency when building releases (MR
• Object life cycle fixes (MR)
• Use DBus activation (MR). This ensures it spawns quickly rather than phosh's splash screen timing out.

bluez

• Add user unit for mpris proxy so it works out of the box (Patch) and one can skip e.g. songs in a cars media unit

gnome-text-editor

• Wrap info-bar more (MR) to fit smalls screens
• Forward metainfo/desktop file updates from Mobian (MR) (patch originally by Arnaud Ferraris)

feedbackd

• Add udev rule to support haptic on Oneplus Fajita / Enchilada's (non-mailine driver) (MR)
• Support alert-slider on OnePlus 6/6T (MR. Based on a script by "isyourbrain foss".
• Release 0.5.0 (MR)
• Improve spec a bit regarding notification events (MR)

Chatty

• Don't send feedback for notifications (MR). The notification daemon does this already.
• Add event for cellbroadcast messages (MR)
• Switch to DBus activation (MR). This ensures the compositor sees the activation token and is will be useful for unified push.
• Don't let scroll_down button take focus (MR). This prevents the OSK from folding when the text view is focused and ones scrolls to the bottom.
• Use revealer to show/hide scroll_down button (MR) - just to make the visual more appealing
• Unbreak messge display (MR)
• Unbreak application icon (MR)
• Drop special preedit handling (MR).

libcall-ui

• Drop margin so we can fit on smaller screens (MR). This helps phosh on lower effective resolutions.
• Backport margin patch (MR)

glib

• Fix doc formatting for g_input_stream_read_all* (MR)

wlr-protocols

• Add toplevel responsiveness state (MR) so phosh can inform about unresponsive apps

git-buildpackage

• Modernize docs to use debian/latest instead of debian/sid (commit, commit).
• Use pytest instead of nose as test runner (MR)
• Release 0.9.35

iio-sensor-proxy

• Unbreak and modernize CI a bit (MR). A passing CI is so much more motivating for contributers and reviewers.

Fotema

• Fix app-id and hence the icon shown in Phosh's overview (MR)

Help Development If you want to support my work see donations. This includes a list of hardware we want to improve support for. Thanks a lot to all current and past donors.

The Reproducible Builds project relies on several projects, supporters and sponsors for financial support, but they are also valued as ambassadors who spread the word about our project and the work that we do. This is the eighth installment in a series featuring the projects, companies and individuals who support the Reproducible Builds project. We started this series by featuring the Civil Infrastructure Platform project, and followed this up with a post about the Ford Foundation as well as recent ones about ARDC, the Google Open Source Security Team (GOSST), Bootstrappable Builds, the F-Droid project, David A. Wheeler and Simon Butler. Today, however, we will be talking with Kees Cook, founder of the Kernel Self-Protection Project.

Vagrant Cascadian: Could you tell me a bit about yourself? What sort of things do you work on? Kees Cook: I m a Free Software junkie living in Portland, Oregon, USA. I have been focusing on the upstream Linux kernel s protection of itself. There is a lot of support that the kernel provides userspace to defend itself, but when I first started focusing on this there was not as much attention given to the kernel protecting itself. As userspace got more hardened the kernel itself became a bigger target. Almost 9 years ago I formally announced the Kernel Self-Protection Project because the work necessary was way more than my time and expertise could do alone. So I just try to get people to help as much as possible; people who understand the ARM architecture, people who understand the memory management subsystem to help, people who understand how to make the kernel less buggy.
Vagrant: Could you describe the path that lead you to working on this sort of thing? Kees: I have always been interested in security through the aspect of exploitable flaws. I always thought it was like a magic trick to make a computer do something that it was very much not designed to do and seeing how easy it is to subvert bugs. I wanted to improve that fragility. In 2006, I started working at Canonical on Ubuntu and was mainly focusing on bringing Debian and Ubuntu up to what was the state of the art for Fedora and Gentoo s security hardening efforts. Both had really pioneered a lot of userspace hardening with compiler flags and ELF stuff and many other things for hardened binaries. On the whole, Debian had not really paid attention to it. Debian s packaging building process at the time was sort of a chaotic free-for-all as there wasn t centralized build methodology for defining things. Luckily that did slowly change over the years. In Ubuntu we had the opportunity to apply top down build rules for hardening all the packages. In 2011 Chrome OS was following along and took advantage of a bunch of the security hardening work as they were based on ebuild out of Gentoo and when they looked for someone to help out they reached out to me. We recognized the Linux kernel was pretty much the weakest link in the Chrome OS security posture and I joined them to help solve that. Their userspace was pretty well handled but the kernel had a lot of weaknesses, so focusing on hardening was the next place to go. When I compared notes with other users of the Linux kernel within Google there were a number of common concerns and desires. Chrome OS already had an upstream first requirement, so I tried to consolidate the concerns and solve them upstream. It was challenging to land anything in other kernel team repos at Google, as they (correctly) wanted to minimize their delta from upstream, so I needed to work on any major improvements entirely in upstream and had a lot of support from Google to do that. As such, my focus shifted further from working directly on Chrome OS into being entirely upstream and being more of a consultant to internal teams, helping with integration or sometimes backporting. Since the volume of needed work was so gigantic I needed to find ways to inspire other developers (both inside and outside of Google) to help. Once I had a budget I tried to get folks paid (or hired) to work on these areas when it wasn t already their job.
Vagrant: So my understanding of some of your recent work is basically defining undefined behavior in the language or compiler? Kees: I ve found the term undefined behavior to have a really strict meaning within the compiler community, so I have tried to redefine my goal as eliminating unexpected behavior or ambiguous language constructs . At the end of the day ambiguity leads to bugs, and bugs lead to exploitable security flaws. I ve been taking a four-pronged approach: supporting the work people are doing to get rid of ambiguity, identify new areas where ambiguity needs to be removed, actually removing that ambiguity from the C language, and then dealing with any needed refactoring in the Linux kernel source to adapt to the new constraints. None of this is particularly novel; people have recognized how dangerous some of these language constructs are for decades and decades but I think it is a combination of hard problems and a lot of refactoring that nobody has the interest/resources to do. So, we have been incrementally going after the lowest hanging fruit. One clear example in recent years was the elimination of C s implicit fall-through in switch statements. The language would just fall through between adjacent cases if a break (or other code flow directive) wasn t present. But this is ambiguous: is the code meant to fall-through, or did the author just forget a break statement? By defining the [[fallthrough]] statement, and requiring its use in Linux, all switch statements now have explicit code flow, and the entire class of bugs disappeared. During our refactoring we actually found that 1 in 10 added [[fallthrough]] statements were actually missing break statements. This was an extraordinarily common bug! So getting rid of that ambiguity is where we have been. Another area I ve been spending a bit of time on lately is looking at how defensive security work has challenges associated with metrics. How do you measure your defensive security impact? You can t say because we installed locks on the doors, 20% fewer break-ins have happened. Much of our signal is always secondary or retrospective, which is frustrating: This class of flaw was used X much over the last decade so, and if we have eliminated that class of flaw and will never see it again, what is the impact? Is the impact infinity? Attackers will just move to the next easiest thing. But it means that exploitation gets incrementally more difficult. As attack surfaces are reduced, the expense of exploitation goes up.
Vagrant: So it is hard to identify how effective this is how bad would it be if people just gave up? Kees: I think it would be pretty bad, because as we have seen, using secondary factors, the work we have done in the industry at large, not just the Linux kernel, has had an impact. What we, Microsoft, Apple, and everyone else is doing for their respective software ecosystems, has shown that the price of functional exploits in the black market has gone up. Especially for really egregious stuff like a zero-click remote code execution. If those were cheap then obviously we are not doing something right, and it becomes clear that it s trivial for anyone to attack the infrastructure that our lives depend on. But thankfully we have seen over the last two decades that prices for exploits keep going up and up into millions of dollars. I think it is important to keep working on that because, as a central piece of modern computer infrastructure, the Linux kernel has a giant target painted on it. If we give up, we have to accept that our computers are not doing what they were designed to do, which I can t accept. The safety of my grandparents shouldn t be any different from the safety of journalists, and political activists, and anyone else who might be the target of attacks. We need to be able to trust our devices otherwise why use them at all?
Vagrant: What has been your biggest success in recent years? Kees: I think with all these things I am not the only actor. Almost everything that we have been successful at has been because of a lot of people s work, and one of the big ones that has been coordinated across the ecosystem and across compilers was initializing stack variables to 0 by default. This feature was added in Clang, GCC, and MSVC across the board even though there were a lot of fears about forking the C language. The worry was that developers would come to depend on zero-initialized stack variables, but this hasn t been the case because we still warn about uninitialized variables when the compiler can figure that out. So you still still get the warnings at compile time but now you can count on the contents of your stack at run-time and we drop an entire class of uninitialized variable flaws. While the exploitation of this class has mostly been around memory content exposure, it has also been used for control flow attacks. So that was politically and technically a large challenge: convincing people it was necessary, showing its utility, and implementing it in a way that everyone would be happy with, resulting in the elimination of a large and persistent class of flaws in C.
Vagrant: In a world where things are generally Reproducible do you see ways in which that might affect your work? Kees: One of the questions I frequently get is, What version of the Linux kernel has feature $foo? If I know how things are built, I can answer with just a version number. In a Reproducible Builds scenario I can count on the compiler version, compiler flags, kernel configuration, etc. all those things are known, so I can actually answer definitively that a certain feature exists. So that is an area where Reproducible Builds affects me most directly. Indirectly, it is just being able to trust the binaries you are running are going to behave the same for the same build environment is critical for sane testing.
Vagrant: Have you used diffoscope? Kees: I have! One subset of tree-wide refactoring that we do when getting rid of ambiguous language usage in the kernel is when we have to make source level changes to satisfy some new compiler requirement but where the binary output is not expected to change at all. It is mostly about getting the compiler to understand what is happening, what is intended in the cases where the old ambiguity does actually match the new unambiguous description of what is intended. The binary shouldn t change. We have used diffoscope to compare the before and after binaries to confirm that yep, there is no change in binary .
Vagrant: You cannot just use checksums for that? Kees: For the most part, we need to only compare the text segments. We try to hold as much stable as we can, following the Reproducible Builds documentation for the kernel, but there are macros in the kernel that are sensitive to source line numbers and as a result those will change the layout of the data segment (and sometimes the text segment too). With diffoscope there s flexibility where I can exclude or include different comparisons. Sometimes I just go look at what diffoscope is doing and do that manually, because I can tweak that a little harder, but diffoscope is definitely the default. Diffoscope is awesome!
Vagrant: Where has reproducible builds affected you? Kees: One of the notable wins of reproducible builds lately was dealing with the fallout of the XZ backdoor and just being able to ask the question is my build environment running the expected code? and to be able to compare the output generated from one install that never had a vulnerable XZ and one that did have a vulnerable XZ and compare the results of what you get. That was important for kernel builds because the XZ threat actor was working to expand their influence and capabilities to include Linux kernel builds, but they didn t finish their work before they were noticed. I think what happened with Debian proving the build infrastructure was not affected is an important example of how people would have needed to verify the kernel builds too.
Vagrant: What do you want to see for the near or distant future in security work? Kees: For reproducible builds in the kernel, in the work that has been going on in the ClangBuiltLinux project, one of the driving forces of code and usability quality has been the continuous integration work. As soon as something breaks, on the kernel side, the Clang side, or something in between the two, we get a fast signal and can chase it and fix the bugs quickly. I would like to see someone with funding to maintain a reproducible kernel build CI. There have been places where there are certain architecture configurations or certain build configuration where we lose reproducibility and right now we have sort of a standard open source development feedback loop where those things get fixed but the time in between introduction and fix can be large. Getting a CI for reproducible kernels would give us the opportunity to shorten that time.
Vagrant: Well, thanks for that! Any last closing thoughts? Kees: I am a big fan of reproducible builds, thank you for all your work. The world is a safer place because of it.
Vagrant: Likewise for your work!

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For more information about the Reproducible Builds project, please see our website at reproducible-builds.org. If you are interested in ensuring the ongoing security of the software that underpins our civilisation and wish to sponsor the Reproducible Builds project, please reach out to the project by emailing contact@reproducible-builds.org.

Hey everyone! The 2024 Linux Display Next hackfest concluded in May, and its outcomes continue to shape the Linux Display stack. Igalia hosted this year s event in A Coru a, Spain, bringing together leading experts in the field. Samuel Iglesias and I organized this year s edition and this blog post summarizes the experience and its fruits. One of the highlights of this year s hackfest was the wide range of backgrounds represented by our 40 participants (both on-site and remotely). Developers and experts from various companies and open-source projects came together to advance the Linux Display ecosystem. You can find the list of participants here. The event covered a broad spectrum of topics affecting the development of Linux projects, user experiences, and the future of display technologies on Linux. From cutting-edge topics to long-term discussions, you can check the event agenda here.

Organization Highlights The hackfest was marked by in-depth discussions and knowledge sharing among Linux contributors, making everyone inspired, informed, and connected to the community. Building on feedback from the previous year, we refined the unconference format to enhance participant preparation and engagement. Structured Agenda and Timeboxes: Each session had a defined scope, time limit (1h20 or 2h10), and began with an introductory talk on the topic.

• Participant-Led Discussions: We pre-selected in-person participants to lead discussions, allowing them to prepare introductions, resources, and scope.
• Transparent Scheduling: The schedule was shared in advance as GitHub issues, encouraging participants to review and prepare for sessions of interest.

Engaging Sessions: The hackfest featured a variety of topics, including presentations and discussions on how participants were addressing specific subjects within their companies.

• No Breakout Rooms, No Overlaps: All participants chose to attend all sessions, eliminating the need for separate breakout rooms. We also adapted run-time schedule to keep everybody involved in the same topics.
• Real-time Updates: We provided notifications and updates through dedicated emails and the event matrix room.

Strengthening Community Connections: The hackfest offered ample opportunities for networking among attendees.

• Social Events: Igalia sponsored coffee breaks, lunches, and a dinner at a local restaurant.
• Museum Visit: Participants enjoyed a sponsored visit to the Museum of Estrela Galicia Beer (MEGA).

Fruitful Discussions and Follow-up The structured agenda and breaks allowed us to cover multiple topics during the hackfest. These discussions have led to new display feature development and improvements, as evidenced by patches, merge requests, and implementations in project repositories and mailing lists. With the KMS color management API taking shape, we discussed refinements and best approaches to cover the variety of color pipeline from different hardware-vendors. We are also investigating techniques for a performant SDR<->HDR content reproduction and reducing latency and power consumption when using the color blocks of the hardware.

Color Management/HDR Color Management and HDR continued to be the hottest topic of the hackfest. We had three sessions dedicated to discuss Color and HDR across Linux Display stack layers.

Color/HDR (Kernel-Level) Harry Wentland (AMD) led this session. Here, kernel Developers shared the Color Management pipeline of AMD, Intel and NVidia. We counted with diagrams and explanations from HW-vendors developers that discussed differences, constraints and paths to fit them into the KMS generic color management properties such as advertising modeset needs, IN\_FORMAT, segmented LUTs, interpolation types, etc. Developers from Qualcomm and ARM also added information regarding their hardware. Upstream work related to this session:

• KMS color management properties (new version - v5);
• IGT Tests;
• drm_info draft support of v4 DRM/KMS plane color properties;
• gamescope draft support of v4 DRM/KMS plane color properties;
• Kwin WIP implementation of DRM/KMS plane color properties.

Color/HDR (Compositor-Level) Sebastian Wick (RedHat) led this session. It started with Sebastian s presentation covering Wayland color protocols and compositor implementation. Also, an explanation of APIs provided by Wayland and how they can be used to achieve better color management for applications and discussions around ICC profiles and color representation metadata. There was also an intensive Q&A about LittleCMS with Marti Maria. Upstream work related to this session:

• Wayland color management protocol;
• Wayland color representation protocol;
• HDR support merged on Mutter;
• Color management protocol on Mutter;
• Color management protocol on GTK.

Color/HDR (Use Cases and Testing) Christopher Cameron (Google) and Melissa Wen (Igalia) led this session. In contrast to the other sessions, here we focused less on implementation and more on brainstorming and reflections of real-world SDR and HDR transformations (use and validation) and gainmaps. Christopher gave a nice presentation explaining HDR gainmap images and how we should think of HDR. This presentation and Q&A were important to put participants at the same page of how to transition between SDR and HDR and somehow emulating HDR. We also discussed on the usage of a kernel background color property. Finally, we discussed a bit about Chamelium and the future of VKMS (future work and maintainership).

Power Savings vs Color/Latency Mario Limonciello (AMD) led this session. Mario gave an introductory presentation about AMD ABM (adaptive backlight management) that is similar to Intel DPST. After some discussions, we agreed on exposing a kernel property for power saving policy. This work was already merged on kernel and the userspace support is under development. Upstream work related to this session:

• Kernel series: Add support for power saving policy property (merged)
• Mutter: issue: support for power saving policy property
• Kwin: MR Draft: backends/drm: add support for the power saving policy property

Strategy for video and gaming use-cases Leo Li (AMD) led this session. Miguel Casas (Google) started this session with a presentation of Overlays in Chrome/OS Video, explaining the main goal of power saving by switching off GPU for accelerated compositing and the challenges of different colorspace/HDR for video on Linux. Then Leo Li presented different strategies for video and gaming and we discussed the userspace need of more detailed feedback mechanisms to understand failures when offloading. Also, creating a debugFS interface came up as a tool for debugging and analysis.

Real-time scheduling and async KMS API Xaver Hugl (KDE/BlueSystems) led this session. Compositor developers have exposed some issues with doing real-time scheduling and async page flips. One is that the Kernel limits the lifetime of realtime threads and if a modeset takes too long, the thread will be killed and thus the compositor as well. Also, simple page flips take longer than expected and drivers should optimize them. Another issue is the lack of feedback to compositors about hardware programming time and commit deadlines (the lastest possible time to commit). This is difficult to predict from drivers, since it varies greatly with the type of properties. For example, color management updates take much longer. In this regard, we discusssed implementing a hw_done callback to timestamp when the hardware programming of the last atomic commit is complete. Also an API to pre-program color pipeline in a kind of A/B scheme. It may not be supported by all drivers, but might be useful in different ways.

VRR/Frame Limit, Display Mux, Display Control, and more and beer We also had sessions to discuss a new KMS API to mitigate headaches on VRR and Frame Limit as different brightness level at different refresh rates, abrupt changes of refresh rates, low frame rate compensation (LFC) and precise timing in VRR more. On Display Control we discussed features missing in the current KMS interface for HDR mode, atomic backlight settings, source-based tone mapping, etc. We also discussed the need of a place where compositor developers can post TODOs to be developed by KMS people. The Content-adaptive Scaling and Sharpening session focused on sharpening and scaling filters. In the Display Mux session, we discussed proposals to expose the capability of dynamic mux switching display signal between discrete and integrated GPUs. In the last session of the 2024 Display Next Hackfest, participants representing different compositors summarized current and future work and built a Linux Display wish list , which includes: improvements to VTTY and HDR switching, better dmabuf API for multi-GPU support, definition of tone mapping, blending and scaling sematics, and wayland protocols for advertising to clients which colorspaces are supported. We closed this session with a status update on feature development by compositors, including but not limited to: plane offloading (from libcamera to output) / HDR video offloading (dma-heaps) / plane-based scrolling for web pages, color management / HDR / ICC profiles support, addressing issues such as flickering when color primaries don t match, etc. After three days of intensive discussions, all in-person participants went to a guided tour at the Museum of Extrela Galicia beer (MEGA), pouring and tasting the most famous local beer.

Feedback and Future Directions Participants provided valuable feedback on the hackfest, including suggestions for future improvements.

• Schedule and Break-time Setup: Having a pre-defined agenda and schedule provided a better balance between long discussions and mental refreshments, preventing the fatigue caused by endless discussions.
• Action Points: Some participants recommended explicitly asking for action points at the end of each session and assigning people to follow-up tasks.
• Remote Participation: Remote attendees appreciated the inclusive setup and opportunities to actively participate in discussions.
• Technical Challenges: There were bandwidth and video streaming issues during some sessions due to the large number of participants.

Thank you for joining the 2024 Display Next Hackfest We can t help but thank the 40 participants, who engaged in-person or virtually on relevant discussions, for a collaborative evolution of the Linux display stack and for building an insightful agenda. A big thank you to the leaders and presenters of the nine sessions: Christopher Cameron (Google), Harry Wentland (AMD), Leo Li (AMD), Mario Limoncello (AMD), Sebastian Wick (RedHat) and Xaver Hugl (KDE/BlueSystems) for the effort in preparing the sessions, explaining the topic and guiding discussions. My acknowledge to the others in-person participants that made such an effort to travel to A Coru a: Alex Goins (NVIDIA), David Turner (Raspberry Pi), Georges Stavracas (Igalia), Joan Torres (SUSE), Liviu Dudau (Arm), Louis Chauvet (Bootlin), Robert Mader (Collabora), Tian Mengge (GravityXR), Victor Jaquez (Igalia) and Victoria Brekenfeld (System76). It was and awesome opportunity to meet you and chat face-to-face. Finally, thanks virtual participants who couldn t make it in person but organized their days to actively participate in each discussion, adding different perspectives and valuable inputs even remotely: Abhinav Kumar (Qualcomm), Chaitanya Borah (Intel), Christopher Braga (Qualcomm), Dor Askayo (Red Hat), Jiri Koten (RedHat), Jonas dahl (Red Hat), Leandro Ribeiro (Collabora), Marti Maria (Little CMS), Marijn Suijten, Mario Kleiner, Martin Stransky (Red Hat), Michel D nzer (Red Hat), Miguel Casas-Sanchez (Google), Mitulkumar Golani (Intel), Naveen Kumar (Intel), Niels De Graef (Red Hat), Pekka Paalanen (Collabora), Pichika Uday Kiran (AMD), Shashank Sharma (AMD), Sriharsha PV (AMD), Simon Ser, Uma Shankar (Intel) and Vikas Korjani (AMD). We look forward to another successful Display Next hackfest, continuing to drive innovation and improvement in the Linux display ecosystem!

Hey everyone! The 2024 Linux Display Next hackfest concluded in May, and its outcomes continue to shape the Linux Display stack. Igalia hosted this year s event in A Coru a, Spain, bringing together leading experts in the field. Samuel Iglesias and I organized this year s edition and this blog post summarizes the experience and its fruits. One of the highlights of this year s hackfest was the wide range of backgrounds represented by our 40 participants (both on-site and remotely). Developers and experts from various companies and open-source projects came together to advance the Linux Display ecosystem. You can find the list of participants here. The event covered a broad spectrum of topics affecting the development of Linux projects, user experiences, and the future of display technologies on Linux. From cutting-edge topics to long-term discussions, you can check the event agenda here.

Organization Highlights The hackfest was marked by in-depth discussions and knowledge sharing among Linux contributors, making everyone inspired, informed, and connected to the community. Building on feedback from the previous year, we refined the unconference format to enhance participant preparation and engagement. Structured Agenda and Timeboxes: Each session had a defined scope, time limit (1h20 or 2h10), and began with an introductory talk on the topic.

• Participant-Led Discussions: We pre-selected in-person participants to lead discussions, allowing them to prepare introductions, resources, and scope.
• Transparent Scheduling: The schedule was shared in advance as GitHub issues, encouraging participants to review and prepare for sessions of interest.

Engaging Sessions: The hackfest featured a variety of topics, including presentations and discussions on how participants were addressing specific subjects within their companies.

• No Breakout Rooms, No Overlaps: All participants chose to attend all sessions, eliminating the need for separate breakout rooms. We also adapted run-time schedule to keep everybody involved in the same topics.
• Real-time Updates: We provided notifications and updates through dedicated emails and the event matrix room.

Strengthening Community Connections: The hackfest offered ample opportunities for networking among attendees.

• Social Events: Igalia sponsored coffee breaks, lunches, and a dinner at a local restaurant.
• Museum Visit: Participants enjoyed a sponsored visit to the Museum of Estrela Galicia Beer (MEGA).

Fruitful Discussions and Follow-up The structured agenda and breaks allowed us to cover multiple topics during the hackfest. These discussions have led to new display feature development and improvements, as evidenced by patches, merge requests, and implementations in project repositories and mailing lists. With the KMS color management API taking shape, we discussed refinements and best approaches to cover the variety of color pipeline from different hardware-vendors. We are also investigating techniques for a performant SDR<->HDR content reproduction and reducing latency and power consumption when using the color blocks of the hardware.

Color Management/HDR Color Management and HDR continued to be the hottest topic of the hackfest. We had three sessions dedicated to discuss Color and HDR across Linux Display stack layers.

Color/HDR (Kernel-Level) Harry Wentland (AMD) led this session. Here, kernel Developers shared the Color Management pipeline of AMD, Intel and NVidia. We counted with diagrams and explanations from HW-vendors developers that discussed differences, constraints and paths to fit them into the KMS generic color management properties such as advertising modeset needs, IN\_FORMAT, segmented LUTs, interpolation types, etc. Developers from Qualcomm and ARM also added information regarding their hardware. Upstream work related to this session:

• KMS color management properties (new version - v5);
• IGT Tests;
• drm_info draft support of v4 DRM/KMS plane color properties;
• gamescope draft support of v4 DRM/KMS plane color properties;
• Kwin WIP implementation of DRM/KMS plane color properties.

Color/HDR (Compositor-Level) Sebastian Wick (RedHat) led this session. It started with Sebastian s presentation covering Wayland color protocols and compositor implementation. Also, an explanation of APIs provided by Wayland and how they can be used to achieve better color management for applications and discussions around ICC profiles and color representation metadata. There was also an intensive Q&A about LittleCMS with Marti Maria. Upstream work related to this session:

• Wayland color management protocol;
• Wayland color representation protocol;
• HDR support merged on Mutter;
• Color management protocol on Mutter;
• Color management protocol on GTK.

Color/HDR (Use Cases and Testing) Christopher Cameron (Google) and Melissa Wen (Igalia) led this session. In contrast to the other sessions, here we focused less on implementation and more on brainstorming and reflections of real-world SDR and HDR transformations (use and validation) and gainmaps. Christopher gave a nice presentation explaining HDR gainmap images and how we should think of HDR. This presentation and Q&A were important to put participants at the same page of how to transition between SDR and HDR and somehow emulating HDR. We also discussed on the usage of a kernel background color property. Finally, we discussed a bit about Chamelium and the future of VKMS (future work and maintainership).

Power Savings vs Color/Latency Mario Limonciello (AMD) led this session. Mario gave an introductory presentation about AMD ABM (adaptive backlight management) that is similar to Intel DPST. After some discussions, we agreed on exposing a kernel property for power saving policy. This work was already merged on kernel and the userspace support is under development. Upstream work related to this session:

• Kernel series: Add support for power saving policy property (merged)
• Mutter: issue: support for power saving policy property
• Kwin: MR Draft: backends/drm: add support for the power saving policy property

Strategy for video and gaming use-cases Leo Li (AMD) led this session. Miguel Casas (Google) started this session with a presentation of Overlays in Chrome/OS Video, explaining the main goal of power saving by switching off GPU for accelerated compositing and the challenges of different colorspace/HDR for video on Linux. Then Leo Li presented different strategies for video and gaming and we discussed the userspace need of more detailed feedback mechanisms to understand failures when offloading. Also, creating a debugFS interface came up as a tool for debugging and analysis.

Real-time scheduling and async KMS API Xaver Hugl (KDE/BlueSystems) led this session. Compositor developers have exposed some issues with doing real-time scheduling and async page flips. One is that the Kernel limits the lifetime of realtime threads and if a modeset takes too long, the thread will be killed and thus the compositor as well. Also, simple page flips take longer than expected and drivers should optimize them. Another issue is the lack of feedback to compositors about hardware programming time and commit deadlines (the lastest possible time to commit). This is difficult to predict from drivers, since it varies greatly with the type of properties. For example, color management updates take much longer. In this regard, we discusssed implementing a hw_done callback to timestamp when the hardware programming of the last atomic commit is complete. Also an API to pre-program color pipeline in a kind of A/B scheme. It may not be supported by all drivers, but might be useful in different ways.

VRR/Frame Limit, Display Mux, Display Control, and more and beer We also had sessions to discuss a new KMS API to mitigate headaches on VRR and Frame Limit as different brightness level at different refresh rates, abrupt changes of refresh rates, low frame rate compensation (LFC) and precise timing in VRR more. On Display Control we discussed features missing in the current KMS interface for HDR mode, atomic backlight settings, source-based tone mapping, etc. We also discussed the need of a place where compositor developers can post TODOs to be developed by KMS people. The Content-adaptive Scaling and Sharpening session focused on sharpening and scaling filters. In the Display Mux session, we discussed proposals to expose the capability of dynamic mux switching display signal between discrete and integrated GPUs. In the last session of the 2024 Display Next Hackfest, participants representing different compositors summarized current and future work and built a Linux Display wish list , which includes: improvements to VTTY and HDR switching, better dmabuf API for multi-GPU support, definition of tone mapping, blending and scaling sematics, and wayland protocols for advertising to clients which colorspaces are supported. We closed this session with a status update on feature development by compositors, including but not limited to: plane offloading (from libcamera to output) / HDR video offloading (dma-heaps) / plane-based scrolling for web pages, color management / HDR / ICC profiles support, addressing issues such as flickering when color primaries don t match, etc. After three days of intensive discussions, all in-person participants went to a guided tour at the Museum of Extrela Galicia beer (MEGA), pouring and tasting the most famous local beer.

Feedback and Future Directions Participants provided valuable feedback on the hackfest, including suggestions for future improvements.

• Schedule and Break-time Setup: Having a pre-defined agenda and schedule provided a better balance between long discussions and mental refreshments, preventing the fatigue caused by endless discussions.
• Action Points: Some participants recommended explicitly asking for action points at the end of each session and assigning people to follow-up tasks.
• Remote Participation: Remote attendees appreciated the inclusive setup and opportunities to actively participate in discussions.
• Technical Challenges: There were bandwidth and video streaming issues during some sessions due to the large number of participants.

Thank you for joining the 2024 Display Next Hackfest We can t help but thank the 40 participants, who engaged in-person or virtually on relevant discussions, for a collaborative evolution of the Linux display stack and for building an insightful agenda. A big thank you to the leaders and presenters of the nine sessions: Christopher Cameron (Google), Harry Wentland (AMD), Leo Li (AMD), Mario Limoncello (AMD), Sebastian Wick (RedHat) and Xaver Hugl (KDE/BlueSystems) for the effort in preparing the sessions, explaining the topic and guiding discussions. My acknowledge to the others in-person participants that made such an effort to travel to A Coru a: Alex Goins (NVIDIA), David Turner (Raspberry Pi), Georges Stavracas (Igalia), Joan Torres (SUSE), Liviu Dudau (Arm), Louis Chauvet (Bootlin), Robert Mader (Collabora), Tian Mengge (GravityXR), Victor Jaquez (Igalia) and Victoria Brekenfeld (System76). It was and awesome opportunity to meet you and chat face-to-face. Finally, thanks virtual participants who couldn t make it in person but organized their days to actively participate in each discussion, adding different perspectives and valuable inputs even remotely: Abhinav Kumar (Qualcomm), Chaitanya Borah (Intel), Christopher Braga (Qualcomm), Dor Askayo, Jiri Koten (RedHat), Jonas dahl (Red Hat), Leandro Ribeiro (Collabora), Marti Maria (Little CMS), Marijn Suijten, Mario Kleiner, Martin Stransky (Red Hat), Michel D nzer (Red Hat), Miguel Casas-Sanchez (Google), Mitulkumar Golani (Intel), Naveen Kumar (Intel), Niels De Graef (Red Hat), Pekka Paalanen (Collabora), Pichika Uday Kiran (AMD), Shashank Sharma (AMD), Sriharsha PV (AMD), Simon Ser, Uma Shankar (Intel) and Vikas Korjani (AMD). We look forward to another successful Display Next hackfest, continuing to drive innovation and improvement in the Linux display ecosystem!

During COVID companies suddenly found themselves able to offer remote working where it hadn t previously been on offer. That s changed over the past 2 or so years, with most places I m aware of moving back from a fully remote situation to either some sort of hybrid, or even full time office attendance. For example last week Amazon announced a full return to office, having already pulled remote-hired workers in for 3 days a week. I ve seen a lot of folk stating they ll never work in an office again, and that RTO is insanity. Despite being lucky enough to work fully remotely (for a role I d been approached about before, but was never prepared to relocate for), I feel the objections from those who are pro-remote often fail to consider the nuances involved. So let s talk about some of the reasons why companies might want to enforce some sort of RTO.

Real estate value Let s clear this one up first. It s not about real estate value, for most companies. City planners and real estate investors might care, but even if your average company owned their building they d close it in an instant all other things being equal. An unoccupied building costs a lot less to maintain. And plenty of companies rent and would save money even if there s a substantial exit fee.

Occupancy levels That said, once you have anyone in the building the equation changes. If you re having to provide power, heating, internet, security/front desk staff etc, you want to make sure you re getting your money s worth. There s no point heating a building that can seat 100 for only 10 people present. One option is to downsize the building, but that leads to not being able to assign everyone a desk, for example. No one I know likes hot desking. There are also scheduling problems about ensuring there are enough desks for everyone who might turn up on a certain day, and you ve ruled out the option of company/office wide events.

Coexistence builds relationships As a remote worker I wish it wasn t true that most people find it easier to form relationships in person, but it is. Some of this can be worked on with specific teambuilding style events, rather than in office working, but I know plenty of folk who hate those as much as they hate the idea of being in the office. I am lucky in that I work with a bunch of folk who are terminally online, so it s much easier to have those casual conversations even being remote, but I also accept I miss out on some things because I m just not in the office regularly enough. You might not care about this ( I just need to put my head down and code, not talk to people ), but don t discount it as a valid reason why companies might want their workers to be in the office. This often matters even more for folk at the start of their career, where having a bunch of experience folk around to help them learn and figure things out ends up working much better in person (my first job offered to let me go mostly remote when I moved to Norwich, but I said no as I knew I wasn t ready for it yet).

Coexistence allows for unexpected interactions People hate the phrase water cooler chat , and I get that, but it covers the idea of casual conversations that just won t happen the same way when people are remote. I experienced this while running Black Cat; every time Simon and I met up in person we had a bunch of useful conversations even though we were on IRC together normally, and had a VoIP setup that meant we regularly talked too. Equally when I was at Nebulon there were conversations I overheard in the office where I was able to correct a misconception or provide extra context. Some of this can be replicated with the right online chat culture, but I ve found many places end up with folk taking conversations to DMs, or they happen in private channels. It happens more naturally in an office environment.

It s easier for bad managers to manage bad performers Again, this falls into the category of things that shouldn t be true, but are. Remote working has increased the ability for people who want to slack off to do so without being easily detected. Ideally what you want is that these folk, if they fail to perform, are then performance managed out of the organisation. That s hard though, there are (rightly) a bunch of rights workers have (I m writing from a UK perspective) around the procedure that needs to be followed. Managers need organisational support in this to make sure they get it right (and folk are given a chance to improve), which is often lacking.

Summary Look, I get there are strong reasons why offering remote is a great thing from the company perspective, but what I ve tried to outline here is that a return-to-office mandate can have some compelling reasons behind it too. Some of those might be things that wouldn t exist in an ideal world, but unfortunately fixing them is a bigger issue than just changing where folk work from. Not acknowledging that just makes any reaction against office work seem ill-informed, to me.

The debridement operation was a success: nothing bad grew afterwards. I was discharged after a couple of nights with crutches, instructions not to weight-bear, a remarkable, portable negative-pressure "Vac" pump that lived by my side, and some strong painkillers. About two weeks later, I had a skin graft. The surgeon took some skin from my thigh and stitched it over the debridement wound. I was discharged same-day, again with the Vac pump, and again with instructions not to weight-bear, at least for a few days. This time I only kept the Vac pump for a week, and after a dressing change (the first time I saw the graft), I was allowed to walk again. Doing so is strangely awkward, and sometimes a little painful. I have physio exercises to help me regain strength and understanding about what I can do. The donor site remained bandaged for another week before I saw it. I was expecting a stitched cut, but the surgeons have removed the top few layers only, leaving what looks more like a graze or sun-burn. There are four smaller, tentative-looking marks adjacent, suggesting they got it right on the fifth attempt. I'm not sure but I think these will all fade away to near-invisibility with time, and they don't hurt at all. I've now been off work for roughly 12 weeks, but I think I am returning very soon. I am looking forward to returning to some sense of normality. It's been an interesting experience. I thought about writing more about what I've gone through, in particular my experiences in Hospital, dealing with the bureaucracy and things falling "between the gaps". Hanif Kureishi has done a better job than I could. It's clear that the NHS is staffed by incredibly passionate people, but there are a lot of structural problems that interfere with care.

Review: The Book That Broke the World, by Mark Lawrence

Series:	Library Trilogy #2
Publisher:	Ace
Copyright:	2024
ISBN:	0-593-43796-9
Format:	Kindle
Pages:	366

The Book That Broke the World is high fantasy and a direct sequel to The Book That Wouldn't Burn. You should not start here. In a delightful break from normal practice, the author provides a useful summary of the previous volume at the start of this book to jog your memory. At the end of The Book That Wouldn't Burn, the characters were scattered and in various states of corporeality after some major revelations about the nature of the Library and the first appearance of the insectile Skeer. The Book That Wouldn't Burn picks up where it left off, and there is a lot more contact with the Skeer, but my guess that they would be the next viewpoint characters does not pan out. Instead, we get a new group and a new protagonist: Celcha, whose sees angels who come to visit her brother. I have complaints, but before I launch into those, I should say that I liked this book apart from the totally unnecessary cannibalism. (I'll get to that.) Livira is a bit sidelined, which is regrettable, but Celcha and her brother are interesting new characters, and both Arpix and Clovis, supporting characters in the first book, get some excellent character development. Similar to the first book, this is a puzzle box story full of world-building tidbits with intellectually-satisfying interactions. Lawrence elaborates and complicates his setting in ways that don't contradict earlier parts of the story but create more room and depth for the characters to be creative. I came away still invested in this world and eager to find out how Lawrence pulls the world-building and narrative threads together. The biggest drawback of this book is that it's not new. My thought after finishing the first book of the series was that if Lawrence had enough world-building ideas to fill three books to that same level of density, this had the potential of being one of my favorite fantasy series of all time. By the end of the second book, I concluded that this is not the case. Instead of showing us new twists and complications the way the first book did throughout, The Book That Broke the World mostly covers the same thematic ground from some new angles. It felt like Lawrence was worried the reader of the first book may not have understood the theme or the world-building, so he spent most of the second book nailing down anything that moved. I found that frustrating. One of the best parts of The Book That Wouldn't Burn was that Lawrence trusted the reader to keep up, which for me hit the glorious but rare sweet spot of pacing where I was figuring out the world at roughly the same pace as the characters. It surprised me in some very enjoyable ways. The Book That Broke the World did not surprise me. There are a few new things, which I enjoyed, and a few elaborations and developments of ideas, which I mostly enjoyed, but I saw the big plot twist coming at least fifty pages before it happened and found the aftermath more annoying than revelatory. It doesn't help that the plot rests on character misunderstandings, one of my least favorite tropes. One of the other disappointments of this book is that the characters stop using the Library as a library. The Library at the center of this series is a truly marvelous piece of world-building with numerous fascinating features that are unrelated to its contents, but Livira used it first and foremost as a repository of books. The first book was full of characters solving problems by finding a relevant book and reading it. In The Book That Broke the World, sadly, this is mostly gone. The Library is mostly reduced to a complicated Big Dumb Object setting. It's still a delightful bit of world-building, and we learn about a few new features, but I only remember two places where the actual books are important to the story. Even the book referenced in the title is mostly important as an artifact with properties unrelated to the words that it contains or to the act of reading it. I think this is a huge lost opportunity and something I hope Lawrence fixes in the last book of the trilogy. This book instead focuses on the politics around the existence of the Library itself. Here I'm cautiously optimistic, although a lot is going to depend on the third book. Lawrence has set up a three-sided argument between groups that I will uncharitably describe as the libertarian techbros, the "burn it all down" reactionaries, and the neoliberal centrist technocrats. All three of those positions suck, and Lawrence had better be setting the stage for Livira to find a different path. Her unwillingness to commit to any of those sides gives me hope, but bringing this plot to a satisfying conclusion is going to be tricky. I hope I like what Lawrence comes up with, but it feels far from certain. It doesn't help that he's started delivering some points with a sledgehammer, and that's where we get to the unnecessary cannibalism. Thankfully this is a fairly small part of the tail end of the book, but it was an unpleasant surprise that I did not want in this novel and that I don't think made the story any better. It's tempting to call the cannibalism gratuitous, but it does fit one of the main themes of this story, namely that humans are depressingly good at using any rule-based object in unexpected and nasty ways that are contrary to the best intentions of the designer. This is the fundamental challenge of the Library as a whole and the question that I suspect the third book will be devoted to addressing, so I understand why Lawrence wanted to emphasize his point. The reason why there is cannibalism here is directly related to a profound misunderstanding of the properties of the library, and I detected an echo of one of C.S. Lewis's arguments in The Last Battle about the nature of Hell. The problem, though, is that this is Satanic baby-killerism, to borrow a term from Fred Clark. There are numerous ways to show this type of perversion of well-intended systems, which I know because Lawrence used other ones in the first book that were more subtle but equally effective. One of the best parts of The Book That Wouldn't Burn is that there were few real villains. The conflict was structural, all sides had valid perspectives, and the ethical points of that story were made with some care and nuance. The problem with cannibalism as it's used here is not merely that it's gross and disgusting and off-putting to the reader, although it is all of those things. If I wanted to read horror, I would read horror novels. I don't appreciate surprise horror used for shock value in regular fantasy. But worse, it's an abandonment of moral nuance. The function of cannibalism in this story is like the function of Satanic baby-killers: it's to signal that these people are wholly and irredeemably evil. They are the Villains, they are Wrong, and they cease to be characters and become symbols of what the protagonists are fighting. This is destructive to the story because it's designed to provoke a visceral short-circuit in the reader and let the author get away with sloppy story-telling. If the author needs to use tactics like this to point out who is the villain, they have failed to set up their moral quandary properly. The worst part is that this was entirely unnecessary because Lawrence's story-telling wasn't sloppy and he set up his moral quandary just fine. No one was confused about the ethical point here. I as the reader was following without difficulty, and had appreciated the subtlety with which Lawrence posed the question. But apparently he thought he was too subtle and decided to come back to the point with a pile-driver. I think that seriously injured the story. The ethical argument here is much more engaging and thought-provoking when it's more finely balanced. That's a lot of complaints, mostly because this is a good book that I badly wanted to be a great book but which kept tripping over its own feet. A lot of trilogies have weak second books. Hopefully this is another example of the mid-story sag, and the finale will be worthy of the start of the story. But I have to admit the moral short-circuiting and the de-emphasis of the actual books in the library has me a bit nervous. I want a lot out of the third book, and I hope I'm not asking this author for too much. If you liked the first book, I think you'll like this one too, with the caveat that it's quite a bit darker and more violent in places, even apart from the surprise cannibalism. But if you've not started this series, you may want to wait for the third book to see if Lawrence can pull off the ending. Followed by The Book That Held Her Heart, currently scheduled for publication in April of 2025. Rating: 7 out of 10

How does Linux move from an awake machine to a hibernating one? How does it then manage to restore all state? These questions led me to read way too much C in trying to figure out how this particular hardware/software boundary is navigated. This investigation will be split into a few parts, with the first one going from invocation of hibernation to synchronizing all filesystems to disk. This article has been written using Linux version 6.9.9, the source of which can be found in many places, but can be navigated easily through the Bootlin Elixir Cross-Referencer: https://elixir.bootlin.com/linux/v6.9.9/source Each code snippet will begin with a link to the above giving the file path and the line number of the beginning of the snippet.

A Starting Point for Investigation: /sys/power/state and /sys/power/disk These two system files exist to allow debugging of hibernation, and thus control the exact state used directly. Writing specific values to the state file controls the exact sleep mode used and disk controls the specific hibernation mode¹. This is extremely handy as an entry point to understand how these systems work, since we can just follow what happens when they are written to.

Show and Store Functions These two files are defined using the power_attr macro: kernel/power/power.h:80

#define power_attr(_name) \
static struct kobj_attribute _name##_attr =     \
    .attr   =               \
        .name = __stringify(_name), \
        .mode = 0644,           \
     ,                  \
    .show   = _name##_show,         \
    .store  = _name##_store,        \
 

show is called on reads and store on writes. state_show is a little boring for our purposes, as it just prints all the available sleep states. kernel/power/main.c:657

/*
 * state - control system sleep states.
 *
 * show() returns available sleep state labels, which may be "mem", "standby",
 * "freeze" and "disk" (hibernation).
 * See Documentation/admin-guide/pm/sleep-states.rst for a description of
 * what they mean.
 *
 * store() accepts one of those strings, translates it into the proper
 * enumerated value, and initiates a suspend transition.
 */
static ssize_t state_show(struct kobject *kobj, struct kobj_attribute *attr,
			  char *buf)
 
	char *s = buf;
#ifdef CONFIG_SUSPEND
	suspend_state_t i;
	for (i = PM_SUSPEND_MIN; i < PM_SUSPEND_MAX; i++)
		if (pm_states[i])
			s += sprintf(s,"%s ", pm_states[i]);
#endif
	if (hibernation_available())
		s += sprintf(s, "disk ");
	if (s != buf)
		/* convert the last space to a newline */
		*(s-1) = '\n';
	return (s - buf);
 

state_store, however, provides our entry point. If the string disk is written to the state file, it calls hibernate(). This is our entry point. kernel/power/main.c:715

static ssize_t state_store(struct kobject *kobj, struct kobj_attribute *attr,
			   const char *buf, size_t n)
 
	suspend_state_t state;
	int error;
	error = pm_autosleep_lock();
	if (error)
		return error;
	if (pm_autosleep_state() > PM_SUSPEND_ON)  
		error = -EBUSY;
		goto out;
	 
	state = decode_state(buf, n);
	if (state < PM_SUSPEND_MAX)  
		if (state == PM_SUSPEND_MEM)
			state = mem_sleep_current;
		error = pm_suspend(state);
	  else if (state == PM_SUSPEND_MAX)  
		error = hibernate();
	  else  
		error = -EINVAL;
	 
 out:
	pm_autosleep_unlock();
	return error ? error : n;
 

kernel/power/main.c:688

static suspend_state_t decode_state(const char *buf, size_t n)
 
#ifdef CONFIG_SUSPEND
	suspend_state_t state;
#endif
	char *p;
	int len;
	p = memchr(buf, '\n', n);
	len = p ? p - buf : n;
	/* Check hibernation first. */
	if (len == 4 && str_has_prefix(buf, "disk"))
		return PM_SUSPEND_MAX;
#ifdef CONFIG_SUSPEND
	for (state = PM_SUSPEND_MIN; state < PM_SUSPEND_MAX; state++)  
		const char *label = pm_states[state];
		if (label && len == strlen(label) && !strncmp(buf, label, len))
			return state;
	 
#endif
	return PM_SUSPEND_ON;
 

Could we have figured this out just via function names? Sure, but this way we know for sure that nothing else is happening before this function is called.

Autosleep Our first detour is into the autosleep system. When checking the state above, you may notice that the kernel grabs the pm_autosleep_lock before checking the current state. autosleep is a mechanism originally from Android that sends the entire system to either suspend or hibernate whenever it is not actively working on anything. This is not enabled for most desktop configurations, since it s primarily for mobile systems and inverts the standard suspend and hibernate interactions. This system is implemented as a workqueue² that checks the current number of wakeup events, processes and drivers that need to run³, and if there aren t any, then the system is put into the autosleep state, typically suspend. However, it could be hibernate if configured that way via /sys/power/autosleep in a similar manner to using /sys/power/state to manually enable hibernation. kernel/power/main.c:841

static ssize_t autosleep_store(struct kobject *kobj,
			       struct kobj_attribute *attr,
			       const char *buf, size_t n)
 
	suspend_state_t state = decode_state(buf, n);
	int error;
	if (state == PM_SUSPEND_ON
	    && strcmp(buf, "off") && strcmp(buf, "off\n"))
		return -EINVAL;
	if (state == PM_SUSPEND_MEM)
		state = mem_sleep_current;
	error = pm_autosleep_set_state(state);
	return error ? error : n;
 
power_attr(autosleep);
#endif /* CONFIG_PM_AUTOSLEEP */

kernel/power/autosleep.c:24

static DEFINE_MUTEX(autosleep_lock);
static struct wakeup_source *autosleep_ws;
static void try_to_suspend(struct work_struct *work)
 
	unsigned int initial_count, final_count;
	if (!pm_get_wakeup_count(&initial_count, true))
		goto out;
	mutex_lock(&autosleep_lock);
	if (!pm_save_wakeup_count(initial_count)  
		system_state != SYSTEM_RUNNING)  
		mutex_unlock(&autosleep_lock);
		goto out;
	 
	if (autosleep_state == PM_SUSPEND_ON)  
		mutex_unlock(&autosleep_lock);
		return;
	 
	if (autosleep_state >= PM_SUSPEND_MAX)
		hibernate();
	else
		pm_suspend(autosleep_state);
	mutex_unlock(&autosleep_lock);
	if (!pm_get_wakeup_count(&final_count, false))
		goto out;
	/*
	 * If the wakeup occurred for an unknown reason, wait to prevent the
	 * system from trying to suspend and waking up in a tight loop.
	 */
	if (final_count == initial_count)
		schedule_timeout_uninterruptible(HZ / 2);
 out:
	queue_up_suspend_work();
 
static DECLARE_WORK(suspend_work, try_to_suspend);
void queue_up_suspend_work(void)
 
	if (autosleep_state > PM_SUSPEND_ON)
		queue_work(autosleep_wq, &suspend_work);
 

The Steps of Hibernation

Hibernation Kernel Config It s important to note that most of the hibernate-specific functions below do nothing unless you ve defined CONFIG_HIBERNATION in your Kconfig⁴. As an example, hibernate itself is defined as the following if CONFIG_HIBERNATE is not set. include/linux/suspend.h:407

static inline int hibernate(void)   return -ENOSYS;  

Check if Hibernation is Available We begin by confirming that we actually can perform hibernation, via the hibernation_available function. kernel/power/hibernate.c:742

if (!hibernation_available())  
	pm_pr_dbg("Hibernation not available.\n");
	return -EPERM;
 

kernel/power/hibernate.c:92

bool hibernation_available(void)
 
	return nohibernate == 0 &&
		!security_locked_down(LOCKDOWN_HIBERNATION) &&
		!secretmem_active() && !cxl_mem_active();
 

nohibernate is controlled by the kernel command line, it s set via either nohibernate or hibernate=no. security_locked_down is a hook for Linux Security Modules to prevent hibernation. This is used to prevent hibernating to an unencrypted storage device, as specified in the manual page kernel_lockdown(7). Interestingly, either level of lockdown, integrity or confidentiality, locks down hibernation because with the ability to hibernate you can extract bascially anything from memory and even reboot into a modified kernel image. secretmem_active checks whether there is any active use of memfd_secret, and if so it prevents hibernation. memfd_secret returns a file descriptor that can be mapped into a process but is specifically unmapped from the kernel s memory space. Hibernating with memory that not even the kernel is supposed to access would expose that memory to whoever could access the hibernation image. This particular feature of secret memory was apparently controversial, though not as controversial as performance concerns around fragmentation when unmapping kernel memory (which did not end up being a real problem). cxl_mem_active just checks whether any CXL memory is active. A full explanation is provided in the commit introducing this check but there s also a shortened explanation from cxl_mem_probe that sets the relevant flag when initializing a CXL memory device. drivers/cxl/mem.c:186

* The kernel may be operating out of CXL memory on this device,
* there is no spec defined way to determine whether this device
* preserves contents over suspend, and there is no simple way
* to arrange for the suspend image to avoid CXL memory which
* would setup a circular dependency between PCI resume and save
* state restoration.

Check Compression The next check is for whether compression support is enabled, and if so whether the requested algorithm is enabled. kernel/power/hibernate.c:747

/*
 * Query for the compression algorithm support if compression is enabled.
 */
if (!nocompress)  
	strscpy(hib_comp_algo, hibernate_compressor, sizeof(hib_comp_algo));
	if (crypto_has_comp(hib_comp_algo, 0, 0) != 1)  
		pr_err("%s compression is not available\n", hib_comp_algo);
		return -EOPNOTSUPP;
	 
 

The nocompress flag is set via the hibernate command line parameter, setting hibernate=nocompress. If compression is enabled, then hibernate_compressor is copied to hib_comp_algo. This synchronizes the current requested compression setting (hibernate_compressor) with the current compression setting (hib_comp_algo). Both values are character arrays of size CRYPTO_MAX_ALG_NAME (128 in this kernel). kernel/power/hibernate.c:50

static char hibernate_compressor[CRYPTO_MAX_ALG_NAME] = CONFIG_HIBERNATION_DEF_COMP;
/*
 * Compression/decompression algorithm to be used while saving/loading
 * image to/from disk. This would later be used in 'kernel/power/swap.c'
 * to allocate comp streams.
 */
char hib_comp_algo[CRYPTO_MAX_ALG_NAME];

hibernate_compressor defaults to lzo if that algorithm is enabled, otherwise to lz4 if enabled⁵. It can be overwritten using the hibernate.compressor setting to either lzo or lz4. kernel/power/Kconfig:95

choice
	prompt "Default compressor"
	default HIBERNATION_COMP_LZO
	depends on HIBERNATION
config HIBERNATION_COMP_LZO
	bool "lzo"
	depends on CRYPTO_LZO
config HIBERNATION_COMP_LZ4
	bool "lz4"
	depends on CRYPTO_LZ4
endchoice
config HIBERNATION_DEF_COMP
	string
	default "lzo" if HIBERNATION_COMP_LZO
	default "lz4" if HIBERNATION_COMP_LZ4
	help
	  Default compressor to be used for hibernation.

kernel/power/hibernate.c:1425

static const char * const comp_alg_enabled[] =  
#if IS_ENABLED(CONFIG_CRYPTO_LZO)
	COMPRESSION_ALGO_LZO,
#endif
#if IS_ENABLED(CONFIG_CRYPTO_LZ4)
	COMPRESSION_ALGO_LZ4,
#endif
 ;
static int hibernate_compressor_param_set(const char *compressor,
		const struct kernel_param *kp)
 
	unsigned int sleep_flags;
	int index, ret;
	sleep_flags = lock_system_sleep();
	index = sysfs_match_string(comp_alg_enabled, compressor);
	if (index >= 0)  
		ret = param_set_copystring(comp_alg_enabled[index], kp);
		if (!ret)
			strscpy(hib_comp_algo, comp_alg_enabled[index],
				sizeof(hib_comp_algo));
	  else  
		ret = index;
	 
	unlock_system_sleep(sleep_flags);
	if (ret)
		pr_debug("Cannot set specified compressor %s\n",
			 compressor);
	return ret;
 
static const struct kernel_param_ops hibernate_compressor_param_ops =  
	.set    = hibernate_compressor_param_set,
	.get    = param_get_string,
 ;
static struct kparam_string hibernate_compressor_param_string =  
	.maxlen = sizeof(hibernate_compressor),
	.string = hibernate_compressor,
 ;

We then check whether the requested algorithm is supported via crypto_has_comp. If not, we bail out of the whole operation with EOPNOTSUPP. As part of crypto_has_comp we perform any needed initialization of the algorithm, loading kernel modules and running initialization code as needed⁶.

Grab Locks The next step is to grab the sleep and hibernation locks via lock_system_sleep and hibernate_acquire. kernel/power/hibernate.c:758

sleep_flags = lock_system_sleep();
/* The snapshot device should not be opened while we're running */
if (!hibernate_acquire())  
	error = -EBUSY;
	goto Unlock;
 

First, lock_system_sleep marks the current thread as not freezable, which will be important later⁷. It then grabs the system_transistion_mutex, which locks taking snapshots or modifying how they are taken, resuming from a hibernation image, entering any suspend state, or rebooting.

The GFP Mask The kernel also issues a warning if the gfp mask is changed via either pm_restore_gfp_mask or pm_restrict_gfp_mask without holding the system_transistion_mutex. GFP flags tell the kernel how it is permitted to handle a request for memory. include/linux/gfp_types.h:12

 * GFP flags are commonly used throughout Linux to indicate how memory
 * should be allocated.  The GFP acronym stands for get_free_pages(),
 * the underlying memory allocation function.  Not every GFP flag is
 * supported by every function which may allocate memory.

In the case of hibernation specifically we care about the IO and FS flags, which are reclaim operators, ways the system is permitted to attempt to free up memory in order to satisfy a specific request for memory. include/linux/gfp_types.h:176

 * Reclaim modifiers
 * -----------------
 * Please note that all the following flags are only applicable to sleepable
 * allocations (e.g. %GFP_NOWAIT and %GFP_ATOMIC will ignore them).
 *
 * %__GFP_IO can start physical IO.
 *
 * %__GFP_FS can call down to the low-level FS. Clearing the flag avoids the
 * allocator recursing into the filesystem which might already be holding
 * locks.

gfp_allowed_mask sets which flags are permitted to be set at the current time. As the comment below outlines, preventing these flags from being set avoids situations where the kernel needs to do I/O to allocate memory (e.g. read/writing swap⁸) but the devices it needs to read/write to/from are not currently available. kernel/power/main.c:24

/*
 * The following functions are used by the suspend/hibernate code to temporarily
 * change gfp_allowed_mask in order to avoid using I/O during memory allocations
 * while devices are suspended.  To avoid races with the suspend/hibernate code,
 * they should always be called with system_transition_mutex held
 * (gfp_allowed_mask also should only be modified with system_transition_mutex
 * held, unless the suspend/hibernate code is guaranteed not to run in parallel
 * with that modification).
 */
static gfp_t saved_gfp_mask;
void pm_restore_gfp_mask(void)
 
	WARN_ON(!mutex_is_locked(&system_transition_mutex));
	if (saved_gfp_mask)  
		gfp_allowed_mask = saved_gfp_mask;
		saved_gfp_mask = 0;
	 
 
void pm_restrict_gfp_mask(void)
 
	WARN_ON(!mutex_is_locked(&system_transition_mutex));
	WARN_ON(saved_gfp_mask);
	saved_gfp_mask = gfp_allowed_mask;
	gfp_allowed_mask &= ~(__GFP_IO   __GFP_FS);
 

Sleep Flags After grabbing the system_transition_mutex the kernel then returns and captures the previous state of the threads flags in sleep_flags. This is used later to remove PF_NOFREEZE if it wasn t previously set on the current thread. kernel/power/main.c:52

unsigned int lock_system_sleep(void)
 
	unsigned int flags = current->flags;
	current->flags  = PF_NOFREEZE;
	mutex_lock(&system_transition_mutex);
	return flags;
 
EXPORT_SYMBOL_GPL(lock_system_sleep);

include/linux/sched.h:1633

#define PF_NOFREEZE		0x00008000	/* This thread should not be frozen */

Then we grab the hibernate-specific semaphore to ensure no one can open a snapshot or resume from it while we perform hibernation. Additionally this lock is used to prevent hibernate_quiet_exec, which is used by the nvdimm driver to active its firmware with all processes and devices frozen, ensuring it is the only thing running at that time⁹. kernel/power/hibernate.c:82

bool hibernate_acquire(void)
 
	return atomic_add_unless(&hibernate_atomic, -1, 0);
 

Prepare Console The kernel next calls pm_prepare_console. This function only does anything if CONFIG_VT_CONSOLE_SLEEP has been set. This prepares the virtual terminal for a suspend state, switching away to a console used only for the suspend state if needed. kernel/power/console.c:130

void pm_prepare_console(void)
 
	if (!pm_vt_switch())
		return;
	orig_fgconsole = vt_move_to_console(SUSPEND_CONSOLE, 1);
	if (orig_fgconsole < 0)
		return;
	orig_kmsg = vt_kmsg_redirect(SUSPEND_CONSOLE);
	return;
 

The first thing is to check whether we actually need to switch the VT kernel/power/console.c:94

/*
 * There are three cases when a VT switch on suspend/resume are required:
 *   1) no driver has indicated a requirement one way or another, so preserve
 *      the old behavior
 *   2) console suspend is disabled, we want to see debug messages across
 *      suspend/resume
 *   3) any registered driver indicates it needs a VT switch
 *
 * If none of these conditions is present, meaning we have at least one driver
 * that doesn't need the switch, and none that do, we can avoid it to make
 * resume look a little prettier (and suspend too, but that's usually hidden,
 * e.g. when closing the lid on a laptop).
 */
static bool pm_vt_switch(void)
 
	struct pm_vt_switch *entry;
	bool ret = true;
	mutex_lock(&vt_switch_mutex);
	if (list_empty(&pm_vt_switch_list))
		goto out;
	if (!console_suspend_enabled)
		goto out;
	list_for_each_entry(entry, &pm_vt_switch_list, head)  
		if (entry->required)
			goto out;
	 
	ret = false;
out:
	mutex_unlock(&vt_switch_mutex);
	return ret;
 

There is an explanation of the conditions under which a switch is performed in the comment above the function, but we ll also walk through the steps here. Firstly we grab the vt_switch_mutex to ensure nothing will modify the list while we re looking at it. We then examine the pm_vt_switch_list. This list is used to indicate the drivers that require a switch during suspend. They register this requirement, or the lack thereof, via pm_vt_switch_required. kernel/power/console.c:31

/**
 * pm_vt_switch_required - indicate VT switch at suspend requirements
 * @dev: device
 * @required: if true, caller needs VT switch at suspend/resume time
 *
 * The different console drivers may or may not require VT switches across
 * suspend/resume, depending on how they handle restoring video state and
 * what may be running.
 *
 * Drivers can indicate support for switchless suspend/resume, which can
 * save time and flicker, by using this routine and passing 'false' as
 * the argument.  If any loaded driver needs VT switching, or the
 * no_console_suspend argument has been passed on the command line, VT
 * switches will occur.
 */
void pm_vt_switch_required(struct device *dev, bool required)

Next, we check console_suspend_enabled. This is set to false by the kernel parameter no_console_suspend, but defaults to true. Finally, if there are any entries in the pm_vt_switch_list, then we check to see if any of them require a VT switch. Only if none of these conditions apply, then we return false. If a VT switch is in fact required, then we move first the currently active virtual terminal/console¹⁰ (vt_move_to_console) and then the current location of kernel messages (vt_kmsg_redirect) to the SUSPEND_CONSOLE. The SUSPEND_CONSOLE is the last entry in the list of possible consoles, and appears to just be a black hole to throw away messages. kernel/power/console.c:16

#define SUSPEND_CONSOLE	(MAX_NR_CONSOLES-1)

Interestingly, these are separate functions because you can use TIOCL_SETKMSGREDIRECT (an ioctl¹¹) to send kernel messages to a specific virtual terminal, but by default its the same as the currently active console. The locations of the previously active console and the previous kernel messages location are stored in orig_fgconsole and orig_kmsg, to restore the state of the console and kernel messages after the machine wakes up again. Interestingly, this means orig_fgconsole also ends up storing any errors, so has to be checked to ensure it s not less than zero before we try to do anything with the kernel messages on both suspend and resume. drivers/tty/vt/vt_ioctl.c:1268

/* Perform a kernel triggered VT switch for suspend/resume */
static int disable_vt_switch;
int vt_move_to_console(unsigned int vt, int alloc)
 
	int prev;
	console_lock();
	/* Graphics mode - up to X */
	if (disable_vt_switch)  
		console_unlock();
		return 0;
	 
	prev = fg_console;
	if (alloc && vc_allocate(vt))  
		/* we can't have a free VC for now. Too bad,
		 * we don't want to mess the screen for now. */
		console_unlock();
		return -ENOSPC;
	 
	if (set_console(vt))  
		/*
		 * We're unable to switch to the SUSPEND_CONSOLE.
		 * Let the calling function know so it can decide
		 * what to do.
		 */
		console_unlock();
		return -EIO;
	 
	console_unlock();
	if (vt_waitactive(vt + 1))  
		pr_debug("Suspend: Can't switch VCs.");
		return -EINTR;
	 
	return prev;
 

Unlike most other locking functions we ve seen so far, console_lock needs to be careful to ensure nothing else is panicking and needs to dump to the console before grabbing the semaphore for the console and setting a couple flags.

Panics Panics are tracked via an atomic integer set to the id of the processor currently panicking. kernel/printk/printk.c:2649

/**
 * console_lock - block the console subsystem from printing
 *
 * Acquires a lock which guarantees that no consoles will
 * be in or enter their write() callback.
 *
 * Can sleep, returns nothing.
 */
void console_lock(void)
 
	might_sleep();
	/* On panic, the console_lock must be left to the panic cpu. */
	while (other_cpu_in_panic())
		msleep(1000);
	down_console_sem();
	console_locked = 1;
	console_may_schedule = 1;
 
EXPORT_SYMBOL(console_lock);

kernel/printk/printk.c:362

/*
 * Return true if a panic is in progress on a remote CPU.
 *
 * On true, the local CPU should immediately release any printing resources
 * that may be needed by the panic CPU.
 */
bool other_cpu_in_panic(void)
 
	return (panic_in_progress() && !this_cpu_in_panic());
 

kernel/printk/printk.c:345

static bool panic_in_progress(void)
 
	return unlikely(atomic_read(&panic_cpu) != PANIC_CPU_INVALID);
 

kernel/printk/printk.c:350

/* Return true if a panic is in progress on the current CPU. */
bool this_cpu_in_panic(void)
 
	/*
	 * We can use raw_smp_processor_id() here because it is impossible for
	 * the task to be migrated to the panic_cpu, or away from it. If
	 * panic_cpu has already been set, and we're not currently executing on
	 * that CPU, then we never will be.
	 */
	return unlikely(atomic_read(&panic_cpu) == raw_smp_processor_id());
 

console_locked is a debug value, used to indicate that the lock should be held, and our first indication that this whole virtual terminal system is more complex than might initially be expected. kernel/printk/printk.c:373

/*
 * This is used for debugging the mess that is the VT code by
 * keeping track if we have the console semaphore held. It's
 * definitely not the perfect debug tool (we don't know if _WE_
 * hold it and are racing, but it helps tracking those weird code
 * paths in the console code where we end up in places I want
 * locked without the console semaphore held).
 */
static int console_locked;

console_may_schedule is used to see if we are permitted to sleep and schedule other work while we hold this lock. As we ll see later, the virtual terminal subsystem is not re-entrant, so there s all sorts of hacks in here to ensure we don t leave important code sections that can t be safely resumed.

Disable VT Switch As the comment below lays out, when another program is handling graphical display anyway, there s no need to do any of this, so the kernel provides a switch to turn the whole thing off. Interestingly, this appears to only be used by three drivers, so the specific hardware support required must not be particularly common.

drivers/gpu/drm/omapdrm/dss
drivers/video/fbdev/geode
drivers/video/fbdev/omap2

drivers/tty/vt/vt_ioctl.c:1308

/*
 * Normally during a suspend, we allocate a new console and switch to it.
 * When we resume, we switch back to the original console.  This switch
 * can be slow, so on systems where the framebuffer can handle restoration
 * of video registers anyways, there's little point in doing the console
 * switch.  This function allows you to disable it by passing it '0'.
 */
void pm_set_vt_switch(int do_switch)
 
	console_lock();
	disable_vt_switch = !do_switch;
	console_unlock();
 
EXPORT_SYMBOL(pm_set_vt_switch);

The rest of the vt_switch_console function is pretty normal, however, simply allocating space if needed to create the requested virtual terminal and then setting the current virtual terminal via set_console.

Virtual Terminal Set Console With set_console, we begin (as if we haven t been already) to enter the madness that is the virtual terminal subsystem. As mentioned previously, modifications to its state must be made very carefully, as other stuff happening at the same time could create complete messes. All this to say, calling set_console does not actually perform any work to change the state of the current console. Instead it indicates what changes it wants and then schedules that work. drivers/tty/vt/vt.c:3153

int set_console(int nr)
 
	struct vc_data *vc = vc_cons[fg_console].d;
	if (!vc_cons_allocated(nr)   vt_dont_switch  
		(vc->vt_mode.mode == VT_AUTO && vc->vc_mode == KD_GRAPHICS))  
		/*
		 * Console switch will fail in console_callback() or
		 * change_console() so there is no point scheduling
		 * the callback
		 *
		 * Existing set_console() users don't check the return
		 * value so this shouldn't break anything
		 */
		return -EINVAL;
	 
	want_console = nr;
	schedule_console_callback();
	return 0;
 

The check for vc->vc_mode == KD_GRAPHICS is where most end-user graphical desktops will bail out of this change, as they re in graphics mode and don t need to switch away to the suspend console. vt_dont_switch is a flag used by the ioctls¹¹ VT_LOCKSWITCH and VT_UNLOCKSWITCH to prevent the system from switching virtual terminal devices when the user has explicitly locked it. VT_AUTO is a flag indicating that automatic virtual terminal switching is enabled¹², and thus deliberate switching to a suspend terminal is not required. However, if you do run your machine from a virtual terminal, then we indicate to the system that we want to change to the requested virtual terminal via the want_console variable and schedule a callback via schedule_console_callback. drivers/tty/vt/vt.c:315

void schedule_console_callback(void)
 
	schedule_work(&console_work);
 

console_work is a workqueue² that will execute the given task asynchronously.

Console Callback drivers/tty/vt/vt.c:3109

/*
 * This is the console switching callback.
 *
 * Doing console switching in a process context allows
 * us to do the switches asynchronously (needed when we want
 * to switch due to a keyboard interrupt).  Synchronization
 * with other console code and prevention of re-entrancy is
 * ensured with console_lock.
 */
static void console_callback(struct work_struct *ignored)
 
	console_lock();
	if (want_console >= 0)  
		if (want_console != fg_console &&
		    vc_cons_allocated(want_console))  
			hide_cursor(vc_cons[fg_console].d);
			change_console(vc_cons[want_console].d);
			/* we only changed when the console had already
			   been allocated - a new console is not created
			   in an interrupt routine */
		 
		want_console = -1;
	 
...

console_callback first looks to see if there is a console change wanted via want_console and then changes to it if it s not the current console and has been allocated already. We do first remove any cursor state with hide_cursor. drivers/tty/vt/vt.c:841

static void hide_cursor(struct vc_data *vc)
 
	if (vc_is_sel(vc))
		clear_selection();
	vc->vc_sw->con_cursor(vc, false);
	hide_softcursor(vc);
 

A full dive into the tty driver is a task for another time, but this should give a general sense of how this system interacts with hibernation.

Notify Power Management Call Chain kernel/power/hibernate.c:767

pm_notifier_call_chain_robust(PM_HIBERNATION_PREPARE, PM_POST_HIBERNATION)

This will call a chain of power management callbacks, passing first PM_HIBERNATION_PREPARE and then PM_POST_HIBERNATION on startup or on error with another callback. kernel/power/main.c:98

int pm_notifier_call_chain_robust(unsigned long val_up, unsigned long val_down)
 
	int ret;
	ret = blocking_notifier_call_chain_robust(&pm_chain_head, val_up, val_down, NULL);
	return notifier_to_errno(ret);
 

The power management notifier is a blocking notifier chain, which means it has the following properties. include/linux/notifier.h:23

 *	Blocking notifier chains: Chain callbacks run in process context.
 *		Callouts are allowed to block.

The callback chain is a linked list with each entry containing a priority and a function to call. The function technically takes in a data value, but it is always NULL for the power management chain. include/linux/notifier.h:49

struct notifier_block;
typedef	int (*notifier_fn_t)(struct notifier_block *nb,
			unsigned long action, void *data);
struct notifier_block  
	notifier_fn_t notifier_call;
	struct notifier_block __rcu *next;
	int priority;
 ;

The head of the linked list is protected by a read-write semaphore. include/linux/notifier.h:65

struct blocking_notifier_head  
	struct rw_semaphore rwsem;
	struct notifier_block __rcu *head;
 ;

Because it is prioritized, appending to the list requires walking it until an item with lower¹³ priority is found to insert the current item before. kernel/notifier.c:252

/*
 *	Blocking notifier chain routines.  All access to the chain is
 *	synchronized by an rwsem.
 */
static int __blocking_notifier_chain_register(struct blocking_notifier_head *nh,
					      struct notifier_block *n,
					      bool unique_priority)
 
	int ret;
	/*
	 * This code gets used during boot-up, when task switching is
	 * not yet working and interrupts must remain disabled.  At
	 * such times we must not call down_write().
	 */
	if (unlikely(system_state == SYSTEM_BOOTING))
		return notifier_chain_register(&nh->head, n, unique_priority);
	down_write(&nh->rwsem);
	ret = notifier_chain_register(&nh->head, n, unique_priority);
	up_write(&nh->rwsem);
	return ret;
 

kernel/notifier.c:20

/*
 *	Notifier chain core routines.  The exported routines below
 *	are layered on top of these, with appropriate locking added.
 */
static int notifier_chain_register(struct notifier_block **nl,
				   struct notifier_block *n,
				   bool unique_priority)
 
	while ((*nl) != NULL)  
		if (unlikely((*nl) == n))  
			WARN(1, "notifier callback %ps already registered",
			     n->notifier_call);
			return -EEXIST;
		 
		if (n->priority > (*nl)->priority)
			break;
		if (n->priority == (*nl)->priority && unique_priority)
			return -EBUSY;
		nl = &((*nl)->next);
	 
	n->next = *nl;
	rcu_assign_pointer(*nl, n);
	trace_notifier_register((void *)n->notifier_call);
	return 0;
 

Each callback can return one of a series of options. include/linux/notifier.h:18

#define NOTIFY_DONE		0x0000		/* Don't care */
#define NOTIFY_OK		0x0001		/* Suits me */
#define NOTIFY_STOP_MASK	0x8000		/* Don't call further */
#define NOTIFY_BAD		(NOTIFY_STOP_MASK 0x0002)
						/* Bad/Veto action */

When notifying the chain, if a function returns STOP or BAD then the previous parts of the chain are called again with PM_POST_HIBERNATION¹⁴ and an error is returned. kernel/notifier.c:107

/**
 * notifier_call_chain_robust - Inform the registered notifiers about an event
 *                              and rollback on error.
 * @nl:		Pointer to head of the blocking notifier chain
 * @val_up:	Value passed unmodified to the notifier function
 * @val_down:	Value passed unmodified to the notifier function when recovering
 *              from an error on @val_up
 * @v:		Pointer passed unmodified to the notifier function
 *
 * NOTE:	It is important the @nl chain doesn't change between the two
 *		invocations of notifier_call_chain() such that we visit the
 *		exact same notifier callbacks; this rules out any RCU usage.
 *
 * Return:	the return value of the @val_up call.
 */
static int notifier_call_chain_robust(struct notifier_block **nl,
				     unsigned long val_up, unsigned long val_down,
				     void *v)
 
	int ret, nr = 0;
	ret = notifier_call_chain(nl, val_up, v, -1, &nr);
	if (ret & NOTIFY_STOP_MASK)
		notifier_call_chain(nl, val_down, v, nr-1, NULL);
	return ret;
 

Each of these callbacks tends to be quite driver-specific, so we ll cease discussion of this here.

Sync Filesystems The next step is to ensure all filesystems have been synchronized to disk. This is performed via a simple helper function that times how long the full synchronize operation, ksys_sync takes. kernel/power/main.c:69

void ksys_sync_helper(void)
 
	ktime_t start;
	long elapsed_msecs;
	start = ktime_get();
	ksys_sync();
	elapsed_msecs = ktime_to_ms(ktime_sub(ktime_get(), start));
	pr_info("Filesystems sync: %ld.%03ld seconds\n",
		elapsed_msecs / MSEC_PER_SEC, elapsed_msecs % MSEC_PER_SEC);
 
EXPORT_SYMBOL_GPL(ksys_sync_helper);

ksys_sync wakes and instructs a set of flusher threads to write out every filesystem, first their inodes¹⁵, then the full filesystem, and then finally all block devices, to ensure all pages are written out to disk. fs/sync.c:87

/*
 * Sync everything. We start by waking flusher threads so that most of
 * writeback runs on all devices in parallel. Then we sync all inodes reliably
 * which effectively also waits for all flusher threads to finish doing
 * writeback. At this point all data is on disk so metadata should be stable
 * and we tell filesystems to sync their metadata via ->sync_fs() calls.
 * Finally, we writeout all block devices because some filesystems (e.g. ext2)
 * just write metadata (such as inodes or bitmaps) to block device page cache
 * and do not sync it on their own in ->sync_fs().
 */
void ksys_sync(void)
 
	int nowait = 0, wait = 1;
	wakeup_flusher_threads(WB_REASON_SYNC);
	iterate_supers(sync_inodes_one_sb, NULL);
	iterate_supers(sync_fs_one_sb, &nowait);
	iterate_supers(sync_fs_one_sb, &wait);
	sync_bdevs(false);
	sync_bdevs(true);
	if (unlikely(laptop_mode))
		laptop_sync_completion();
 

It follows an interesting pattern of using iterate_supers to run both sync_inodes_one_sb and then sync_fs_one_sb on each known filesystem¹⁶. It also calls both sync_fs_one_sb and sync_bdevs twice, first without waiting for any operations to complete and then again waiting for completion¹⁷. When laptop_mode is enabled the system runs additional filesystem synchronization operations after the specified delay without any writes. mm/page-writeback.c:111

/*
 * Flag that puts the machine in "laptop mode". Doubles as a timeout in jiffies:
 * a full sync is triggered after this time elapses without any disk activity.
 */
int laptop_mode;
EXPORT_SYMBOL(laptop_mode);

However, when running a filesystem synchronization operation, the system will add an additional timer to schedule more writes after the laptop_mode delay. We don t want the state of the system to change at all while performing hibernation, so we cancel those timers. mm/page-writeback.c:2198

/*
 * We're in laptop mode and we've just synced. The sync's writes will have
 * caused another writeback to be scheduled by laptop_io_completion.
 * Nothing needs to be written back anymore, so we unschedule the writeback.
 */
void laptop_sync_completion(void)
 
	struct backing_dev_info *bdi;
	rcu_read_lock();
	list_for_each_entry_rcu(bdi, &bdi_list, bdi_list)
		del_timer(&bdi->laptop_mode_wb_timer);
	rcu_read_unlock();
 

As a side note, the ksys_sync function is simply called when the system call sync is used. fs/sync.c:111

SYSCALL_DEFINE0(sync)
 
	ksys_sync();
	return 0;
 

The End of Preparation With that the system has finished preparations for hibernation. This is a somewhat arbitrary cutoff, but next the system will begin a full freeze of userspace to then dump memory out to an image and finally to perform hibernation. All this will be covered in future articles!

1. Hibernation modes are outside of scope for this article, see the previous article for a high-level description of the different types of hibernation.
2. Workqueues are a mechanism for running asynchronous tasks. A full description of them is a task for another time, but the kernel documentation on them is available here: https://www.kernel.org/doc/html/v6.9/core-api/workqueue.html ²
3. This is a bit of an oversimplification, but since this isn t the main focus of this article this description has been kept to a higher level.
4. Kconfig is Linux s build configuration system that sets many different macros to enable/disable various features.
5. Kconfig defaults to the first default found
6. Including checking whether the algorithm is larval? Which appears to indicate that it requires additional setup, but is an interesting choice of name for such a state.
7. Specifically when we get to process freezing, which we ll get to in the next article in this series.
8. Swap space is outside the scope of this article, but in short it is a buffer on disk that the kernel uses to store memory not current in use to free up space for other things. See Swap Management for more details.
9. The code for this is lengthy and tangential, thus it has not been included here. If you re curious about the details of this, see kernel/power/hibernate.c:858 for the details of hibernate_quiet_exec, and drivers/nvdimm/core.c:451 for how it is used in nvdimm.
10. Annoyingly this code appears to use the terms console and virtual terminal interchangeably.
11. ioctls are special device-specific I/O operations that permit performing actions outside of the standard file interactions of read/write/seek/etc. ²
12. I m not entirely clear on how this flag works, this subsystem is particularly complex.
13. In this case a higher number is higher priority.
14. Or whatever the caller passes as val_down, but in this case we re specifically looking at how this is used in hibernation.
15. An inode refers to a particular file or directory within the filesystem. See Wikipedia for more details.
16. Each active filesystem is registed with the kernel through a structure known as a superblock, which contains references to all the inodes contained within the filesystem, as well as function pointers to perform the various required operations, like sync.
17. I m including minimal code in this section, as I m not looking to deep dive into the filesystem code at this time.

Welcome to the August 2024 report from the Reproducible Builds project! Our reports attempt to outline what we ve been up to over the past month, highlighting news items from elsewhere in tech where they are related. As ever, if you are interested in contributing to the project, please visit our Contribute page on our website. Table of contents:

1. LWN: The history, status, and plans for reproducible builds
2. Intermediate Autotools build artifacts removed from PostgreSQL distribution tarballs
3. Distribution news
4. Mailing list news
5. diffoscope
6. Website updates
7. Upstream patches
8. Reproducibility testing framework

---

LWN: The history, status, and plans for reproducible builds The free software newspaper of record, Linux Weekly News, published an in-depth article based on Holger Levsen s talk, Reproducible Builds: The First Eleven Years which was presented at the recent DebConf24 conference in Busan, South Korea. Titled The history, status, and plans for reproducible builds and written by Jake Edge, LWN s article not only summarises Holger s talk and clarifies its message but it links to external information as well. Holger s original talk can also be watched on the DebConf24 webpage (direct .webm link and his HTML slides are available also). There are also a significant number of comments on LWN s page as well. Holger Levsen also headed a scheduled discussion session at DebConf24 on Preserving *other* build artifacts addressing a topic where a number of Debian packages are (or would like to) produce results that are neither the .deb files, the build logs nor the logs of CI tests. This is an issue for reproducible builds as this 4th type of build artifact are typically shipped within the binary .deb packages, and are invariably non-deterministic; thus making the .deb files unreproducible. (A direct .webm link and HTML slides are available).

Intermediate Autotools build artifacts removed from PostgreSQL distribution tarballs Peter Eisentraut wrote a detailed blog post on the subject of The new PostgreSQL 17 make dist . Like many projects, the PostgreSQL database has previously pre-built parts of its GNU Autotools build system: the reason for this is a mix of convenience and traditional practice . Peter astutely notes that this arrangement in the build system is quite tricky as:

You need to carefully maintain the different states of clean source code , partially built source code , and fully built source code , and the commands to transition between them.

However, Peter goes on to mention that:

a lot more attention is nowadays paid to the software supply chain. There are security and legal reasons for this. When users install software, they want to know where it came from, and they want to be sure that they got the right thing, not some fake version or some version of dubious legal provenance.

And cites the XZ Utils backdoor as a reason to care about transparent and reproducible ways of distributing and communicating a source tarball and provenance. Because of this, intermediate build artifacts are now henceforth essentially disallowed from PostgreSQL distribution tarballs.

Distribution news In Debian this month, 30 reviews of Debian packages were added, 17 were updated and 10 were removed this month adding to our knowledge about identified issues. One issue type was added by Chris Lamb, too. [ ] In addition, an issue was filed to update the Salsa CI pipeline (used by 1,000s of Debian packages) to no longer test for reproducibility with reprotest s build_path variation. Holger Levsen provided a rationale for this change in the issue, which has already been made to the tests being performed by tests.reproducible-builds.org.
In Arch Linux this month, Jelle van der Waa published a short blog post on the topic of Investigating creating reproducible images with mkosi, motivated by the desire to make it possible for anyone to re-recreate the official Arch cloud image bit-by-bit identical on their own machine as per [the] reproducible builds definition. In addition, Jelle filed a patch for pacman, the Arch Linux package manager, to respect the SOURCE_DATE_EPOCH environment variable when installing a package.
In openSUSE news, Bernhard M. Wiedemann published another report for that distribution.
In Android news, the IzzyOnDroid project added 49 new rebuilder recipes and now features 256 total reproducible applications representing 21% of the total offerings in the repository. IzzyOnDroid is an F-Droid style repository for Android apps[:] applications in this repository are official binaries built by the original application developers, taken from their resp. repositories (mostly GitHub).

Mailing list news From our mailing list this month:

• Bernhard M. Wiedemann posted a brief message to the list with some helpful information regarding nondeterminism within Rust binaries, positing the use of the codegen-units = 16 default and resulting in a bug being filed in the Rust issue tracker. [ ]
• Bernhard also wrote to the list, following up to a thread in November 2023, on attempts to make the LibreOffice suite of office applications build reproducibly. In the thread from this month, Bernhard could announce that the four patches previously mentioned have landed in LibreOffice upstream.
• Fay Stegerman linked the mailing list to a thread she made on the Signal issue tracker regarding whether device-specific binaries [can] ever be considered meaningfully reproducible . In particular: the whole part about allow[ing] multiple third parties to come to a consensus on a correct result breaks down completely when correct is device-specific and not something everyone can agree on. [ ]
• Developer kpcyrd posted an update for source code indexing project, whatsrc.org. Announcing that it now importing packages from live-bootstrap ( a usable Linux system [that is] created with only human-auditable, and wherever possible, human-written, source code ) into its database of provenance data.
• Lastly, Mechtilde Stehmann posted an update to an earlier thread about how Java builds are not reproducible on the armhf architecture, enquiring how they might gain temporary access to such a machine in order to perform some deeper testing. [ ]

diffoscope diffoscope is our in-depth and content-aware diff utility that can locate and diagnose reproducibility issues. This month, Chris Lamb released versions 274, 275, 276 and 277, uploaded these to Debian, and made the following changes as well:

• New features:
  • Strip ANSI escapes usually colour codes from the output of the Procyon Java decompiler. [ ]
  • Factor out a method for stripping ANSI escapes. [ ]
  • Append output from dumppdf(1) in more cases, avoiding situations where we fallback to a binary diff. [ ]
  • Add support for versions of Perl s IO::Compress::Zip version 2.212. [ ]
• Bug fixes:
  • Also catch RuntimeError exceptions when importing the PyPDF library so that it, or, crucially, its transitive dependencies, cannot not cause diffoscope to traceback at runtime and build time. [ ]
  • Do not call marshal.load( ) of precompiled Python bytecode as it, alas, inherently unsafe. Replace for now with a brief summary of the code section of .pyc. [ ][ ]
  • Don t include excessive debug output when calling dumppdf(1). [ ]
• Testsuite-related changes:
  • Don t bother to check version number in test_python.py: the fixture for this test is fixed. [ ][ ]
  • Update test_zip text fixtures and definitions to support new changes to the Perl IO::Compress library. [ ]

In addition, Mattia Rizzolo updated the available architectures for a number of test dependencies [ ] and Sergei Trofimovich fixed an issue to avoid diffoscope crashing when hashing directory symlinks [ ] and Vagrant Cascadian proposed GNU Guix updates for diffoscope versions 275 and 276 and 277.

Website updates There were a rather substantial number of improvements made to our website this month, including:

• Alba Herrerias:
  • Substantially extend the guidance on the Contribute page. [ ]
• Chris Lamb:
  • Set the future: true configuration value so we render all files and documents in the website, regardless of whether they have a date property in the future. After all, we don t re-generate the website on a timer, and have other ways of making unpublished, draft posts. [ ][ ]
• Fay Stegerman:
  • Add IzzyOnDroid (IoD) to the Projects page. [ ]
• hulkoba:
  • Considerably overhaul the History page in the documentation, linking strip-nondeterminism and SOURCE_DATE_EPOCH [ ], fixing the test statistics link [ ], adjusting the Google Summer of Code application link [ ], a link to a Debian bug [ ], and removed a dead link to the debhelper utility [ ].
  • Use the jekyll-sitemap plugin to create a sitemap for the website. [ ]
  • Use raw HTML to avoid a literal .lead directive appearing in the page. [ ]
  • Fix a number of issues on the Virtual machine drivers page, such as keeping the Gitian info, linking (and then removing) an issue on the Bitcoin issue tracker [ ] and fixing a link to the Bazel website [ ].
  • Address a broken footnote link on the Timestamps page. [ ]
  • Unify the style on the Commandments of Reproducible Builds page in order to match other documentation entries. [ ]
  • Add a table of contents to the main Documentation page. [ ]
  • Avoid a number of so-called here links on the Variations in the build environment page. [ ]
  • Fix a link to the man2html patch on the SOURCE_DATE_EPOCH documentation page. [ ]
  • Fix a link to sources.debian.org on the Randomness page. [ ]
• kpcyrd:
  • Fix a typo on the Variations in the build environment page. [ ]
• Mattia Rizzolo:
  • Add all the sponsors to the Hamburg 2024 summit page. [ ][ ][ ][ ][ ]
  • Fix a link in the summit sponsor prospectus PDF. [ ]
• Pol Dellaiera:
  • Fix the DoI for their thesis on the Publications page. [ ]

Upstream patches The Reproducible Builds project detects, dissects and attempts to fix as many currently-unreproducible packages as possible. We endeavour to send all of our patches upstream where appropriate. This month, we wrote a large number of such patches, including:

• Bernhard M. Wiedemann:
  • agama-integration-tests (uses a random TCP-port number in .lock file)
  • ca-certificates-mozilla:ca-certificates-mozilla-prebuilt
  • cosmic (hash order issue)
  • openSUSE (meta-issue to test reproducibility in the openSUSE Build Service)
  • pop-launcher (parallelism-related issue)
  • post (toolchain-issue, avoiding Rust parallelism)
  • rpm-config-SUSE (date-related issue)
  • rust (Rust toolchain issue)
  • weblate (build gets stuck)
• Chris Lamb:
  • #1078048 filed against scikit-optimize.
  • #1078153 filed against pan.
  • #1078687 filed against tetzle.
  • #1079041 filed against apg.
  • #1079312 filed against receptor.
• James Addison:
  • #1064782 forwarded and merged in bind9-doc
  • #1066083 forwarded and merged in gnome-maps

Reproducibility testing framework The Reproducible Builds project operates a comprehensive testing framework running primarily at tests.reproducible-builds.org in order to check packages and other artifacts for reproducibility. In August, a number of changes were made by Holger Levsen, including:

• Temporarily install the openssl-provider-legacy package for the Debian unstable environments for running diffoscope due to Debian bug #1078944. [ ][ ][ ][ ]
• Mark Debian armhf architecture nodes as being down due to proxy down. [ ][ ]
• Detect proxy failures. [ ][ ][ ]
• Run the index-buildinfo for the builtin-pho script with the -q switch. [ ]
• Disable all Arch Linux reproducible jobs. [ ]

In addition, Mattia Rizzolo updated the website configuration to install the ruby-jekyll-sitemap package as it is now used in the website [ ], Roland Clobus updated the script to build Debian live images to treat openQA issues as warnings [ ], and Vagrant Cascadian marked the cbxi4b node as down [ ].

---

If you are interested in contributing to the Reproducible Builds project, please visit our Contribute page on our website. However, you can get in touch with us via:

• IRC: #reproducible-builds on irc.oftc.net.
• Mastodon: @reproducible_builds@fosstodon.org
• Mailing list: rb-general@lists.reproducible-builds.org
• Twitter: @ReproBuilds

Dear Debian community, this are my bits from DPL for August. Happy Birthday Debian On 16th of August Debian celebrated its 31th birthday. Since I'm unable to write a better text than our great publicity team I'm simply linking to their article for those who might have missed it: https://bits.debian.org/2024/08/debian-turns-31.html Removing more packages from unstable Helmut Grohne argued for more aggressive package removal and sought consensus on a way forward. He provided six examples of processes where packages that are candidates for removal are consuming valuable person-power. I d like to add that the Bug of the Day initiative (see below) also frequently encounters long-unmaintained packages with popcon votes sometimes as low as zero, and often fewer than ten. Helmut's email included a list of packages that would meet the suggested removal criteria. There was some discussion about whether a popcon vote should be included in these criteria, with arguments both for and against it. Although I support including popcon, I acknowledge that Helmut has a valid point in suggesting it be left out. While I ve read several emails in agreement, Scott Kitterman made a valid point "I don't think we need more process. We just need someone to do the work of finding the packages and filing the bugs." I agree that this is crucial to ensure an automated process doesn t lead to unwanted removals. However, I don t see "someone" stepping up to file RM bugs against other maintainers' packages. As long as we have strict ownership of packages, many people are hesitant to touch a package, even for fixing it. Asking for its removal might be even less well-received. Therefore, if an automated procedure were to create RM bugs based on defined criteria, it could help reduce some of the social pressure. In this aspect the opinion of Niels Thykier is interesting: "As much as I want automation, I do not mind the prototype starting as a semi-automatic process if that is what it takes to get started." The urgency of the problem to remove packages was put by CharlesPlessy into the words: "So as of today, it is much less work to keep a package rotting than removing it." My observation when trying to fix the Bug of the Day exactly fits this statement. I would love for this discussion to lead to more aggressive removals that we can agree upon, whether they are automated, semi-automated, or managed by a person processing an automatically generated list (supported by an objective procedure). To use an analogy: I ve found that every image collection improves with aggressive pruning. Similarly, I m convinced that Debian will improve if we remove packages that no longer serve our users well. DEP14 / DEP18 There are two DEPs that affect our workflow for maintaining packages particularly for those who agree on using Git for Debian packages. DEP-14 recommends a standardized layout for Git packaging repositories, which benefits maintainers working across teams and makes it easier for newcomers to learn a consistent repository structure. DEP-14 stalled for various reasons. Sam Hartman suspected it might be because 'it doesn't bring sufficient value.' However, the assumption that git-buildpackage is incompatible with DEP-14 is incorrect, as confirmed by its author, Guido G nther. As one of the two key tools for Debian Git repositories (besides dgit) fully supports DEP-14, though the migration from the previous default is somewhat complex. Some investigation into mass-converting older formats to DEP-14 was conducted by the Perl team, as Gregor Hermann pointed out.. The discussion about DEP-14 resurfaced with the suggestion of DEP-18. Guido G nther proposed the title Encourage Continuous Integration and Merge Request-Based Collaboration for Debian Packages , which more accurately reflects the DEP's technical intent. Otto Kek l inen, who initiated DEP-18 (thank you, Otto), provided a good summary of the current status. He also assembled a very helpful overview of Git and GitLab usage in other Linux distros. More Salsa CI As a result of the DEP-18 discussion, Otto Kek l inen suggested implementing Salsa CI for our top popcon packages. I believe it would be a good idea to enable CI by default across Salsa whenever a new repository is created. Progress in Salsa migration In my campaign, I stated that I aim to reduce the number of packages maintained outside Salsa to below 2,000. As of March 28, 2024, the count was 2,368. Today, it stands at 2,187 (UDD query: SELECT DISTINCT count(*) FROM sources WHERE release = 'sid' and vcs_url not like '%salsa%' ;). After a third of my DPL term (OMG), we've made significant progress, reducing the amount in question (369 packages) by nearly half. I'm pleased with the support from the DDs who moved their packages to Salsa. Some packages were transferred as part of the Bug of the Day initiative (see below). Bug of the Day As announced in my 'Bits from the DPL' talk at DebConf, I started an initiative called Bug of the Day. The goal is to train newcomers in bug triaging by enabling them to tackle small, self-contained QA tasks. We have consistently identified target packages and resolved at least one bug per day, often addressing multiple bugs in a single package. In several cases, we followed the Package Salvaging procedure outlined in the Developers Reference. Most instances were either welcomed by the maintainer or did not elicit a response. Unfortunately, there was one exception where the recipient of the Package Salvage bug expressed significant dissatisfaction. The takeaway is to balance formal procedures with consideration for the recipient s perspective. I'm pleased to confirm that the Matrix channel has seen an increase in active contributors. This aligns with my hope that our efforts would attract individuals interested in QA work. I m particularly pleased that, within just one month, we have had help with both fixing bugs and improving the code that aids in bug selection. As I aim to introduce newcomers to various teams within Debian, I also take the opportunity to learn about each team's specific policies myself. I rely on team members' assistance to adapt to these policies. I find that gaining this practical insight into team dynamics is an effective way to understand the different teams within Debian as DPL. Another finding from this initiative, which aligns with my goal as DPL, is that many of the packages we addressed are already on Salsa but have not been uploaded, meaning their VCS fields are not published. This suggests that maintainers are generally open to managing their packages on Salsa. For packages that were not yet on Salsa, the move was generally welcomed. Publicity team wants you The publicity team has decided to resume regular meetings to coordinate their efforts. Given my high regard for their work, I plan to attend their meetings as frequently as possible, which I began doing with the first IRC meeting. During discussions with some team members, I learned that the team could use additional help. If anyone interested in supporting Debian with non-packaging tasks reads this, please consider introducing yourself to debian-publicity@lists.debian.org. Note that this is a publicly archived mailing list, so it's not the best place for sharing private information. Kind regards Andreas.

Review: Thornhedge, by T. Kingfisher

Publisher:	Tor
Copyright:	2023
ISBN:	1-250-24410-2
Format:	Kindle
Pages:	116

Thornhedge is a fantasy novella by T. Kingfisher, the pen name that Ursula Vernon uses for her adult writing. It won the 2024 Hugo Award for best novella. No matter how much my brain wants to misspell the title, it is a story about a hedge, not a Neolithic earthwork.

The fairy was the greenish-tan color of mushroom stems and her skin bruised blue-black, like mushroom flesh. She had a broad, frog-like face and waterweed hair. She was neither beautiful nor made of malice, as many of the Fair Folk are said to be.

There is a princess asleep in a tower, surrounded by a wall of thorns. Toadling's job is to keep anyone from foolishly breaking in. At first, it was a constant struggle and all that she could manage, but with time, the flood of princes slowed to a trickle. A road was built and abandoned. People fled. There was a plague. With any luck, the tower was finally forgotten. Then a knight shows up. Not a very rich knight, nor a very successful knight. Just a polite and very persistent knight who wants to get into the tower that Toadling does not want him to get into. As you might have guessed, this is a Sleeping Beauty retelling. As you may have also guessed from the author, or from the cover text that says "not all curses should be broken," this version is a bit different. How and why it departs from the original is a surprise that slowly unfolds over the course of the story, in parallel to a delicate, cautious, and delightfully kind-hearted conversation between the knight and the fairy. If you have read a T. Kingfisher story before, particularly one of her fractured fairy tales, you know what to expect. Toadling is one of her typical well-meaning, earnest, slightly awkward protagonists who is just trying to do the right thing in a confusing world full of problems and dangers. She's constantly overwhelmed and yet she keeps going, because what else is there to do. Like a lot of Kingfisher's writing, it's a story about quiet courage from someone who doesn't consider herself courageous. One of the twists this time is that the knight is a character from a similar vein: doggedly unwilling to leave any problem alone, but equally determined to try to be kind. The two of them together make for a story with a gentle and rather melancholy tone. We do, eventually, learn the whole backstory of the tower, the wall of thorns, and Toadling. There is a god, a rather memorable one, who is frustratingly cryptic in the way that gods are. There are monsters who are more loving than most humans. There are humans who turn out to be surprisingly decent when it matters. And, like most of Kingfisher's writing, there is a constant awareness of how complicated the world is, how full it is of people who are just trying to get through each day, and how heavy of burdens people can shoulder when they don't see another way. This story pulled me right in. It is not horror, although there are a few odd bits like there always are in Kingfisher stories. Your largest risk as a reader is that it might make you cry if stories about earnest people doing their best in overwhelming situations hit you that way. My primary complaint is that there was nowhere near enough ending for me. After everything I learned about the characters, I wanted to spend some time with them outside of the bounds of the story. Kingfisher points the reader in a direction and then leaves the rest to your imagination, and I can see why she chose that story construction, but I wanted more catharsis than I got. That complaint aside, this is quintessential T. Kingfisher, and I am unsurprised that it won a Hugo. If you've read any of her other fractured fairy tales, or the 2023 Hugo winner for best novel, you know the sort of stories she tells, and you probably know whether you will like this. I am one of the people who like this. Rating: 8 out of 10

Review: Dark Horse, by Michelle Diener

Series:	Class 5 #1
Publisher:	Eclipse
Copyright:	June 2015
ISBN:	0-9924559-3-6
Format:	Kindle
Pages:	366

Dark Horse is a science fiction romance novel, the first of a five book series as of this writing. It is self-published, although it is sufficiently well-edited and packaged that I had to do some searching to confirm that. Rose was abducted by aliens. The Tecrans picked her up along with a selection of Earth animals, kept her in a cell in their starship, and experimented on her. As the book opens, she has managed to make her escape with the aid of an AI named Sazo who was also imprisoned on the Tecran ship. Sazo dealt with the Tecrans, dropped the ship in the middle of Grih territory, and then got Rose and most of the animals on shuttles to a nearby planet. Dav Jallan is the commander of the ship the Grih sent to investigate the unexplained appearance of a Class 5 Tecran warship in the middle of their territory. The Grih and the Tecran, along with three other species, are members of the United Council, which means in theory they're all at peace. With the Tecran, that theory is often strained. Dav is not going to turn down one of their highly-advanced Class 5 warships delivered to him on a silver platter. There is only the matter of the unexpected cargo, the first orange dots (indicating unknown life forms) that most of the Grih have ever seen. There is a romance. That romance did not work for me. I thought it was highly unprofessional on Dav's part and a bit too obviously constructed on the author's part. It also leans on the subgenre convention that aliens can be remarkably physically similar and sexually compatible, which always causes problems for my suspension of disbelief even though I know it's no less plausible than faster-than-light travel. Despite that, I had so much fun with this book! It was absolutely delightful and weirdly grabby in a way that caught me by surprise. I was skimming some parts of it to write this review and found myself re-reading multiple pages before I dragged myself back on task. I think the most charming part of this book is that the United Council has a law called the Sentient Beings Agreement that makes what the Tecran were doing extremely illegal, and the Grih and the other non-Tecran aliens take this very seriously and with a refreshing lack of cynicism. Rose has a typical human reaction to ending up in a place where she doesn't know the rules and isn't entirely an expected guest. She almost reflexively smoothes over miscommunications and tensions, trying to adapt to their expectations. And then, repeatedly, the Grih realize how much work she's doing to adapt to them, feel enraged at the Tecran and upset that they didn't understand or properly explain something, and find some way to make Rose feel more comfortable. It's surprisingly soothing and comforting to read. It occurred to me in several places that Dark Horse could be read as a wish-fulfillment fantasy of what life as a woman could be like if men took their fair share of the mental load. (This concept is usually applied to housework, but I think it generalizes to other social and communication contexts.) I suspect this was not an accident. There is a lot of wish fulfillment in this book. The Grih are very human-like but hunky, which is convenient for the romance subplot. They struggle to sing, value music exceptionally highly, and consider Rose's speaking voice beautifully musical. Her typical human habit of singing to herself is a source of immediate and almost overwhelming fascination. The supplies Rose takes from the Tecran ship when she flees just happen to be absurdly expensive scented shampoo and equally expensive luxury adaptable clothing. The world she lands on, and the Grih ship, are low-gravity compared to Earth, so Rose is unusually strong for her size. Grih military camouflage has no effect on her human vision. The book is set up to make Rose special. If that type of wish fulfillment is going to grate, wait on this book until you're more in the mood for it. But I like wish fulfillment books when they're done well. Part of why I like to read is to imagine a better world. And Rose isn't doted on; despite their hospitality, she's constantly underestimated by the Grih. Even with their deep belief in the Sentient Beings Agreement, they find it hard to believe that an unknown sentient, even an advanced sentient, is really their equal. Their concern at the start is somewhat patronizing, so watching Rose constantly surprise them delighted the part of my brain that likes both competence porn and deserved reversals, even though the competence here is often due to accidents of biology. It helps that Diener tells the story in alternating perspectives, so the reader first watches Rose do something practical and straightforward from her perspective and then gets to enjoy the profound surprise and chagrin of the aliens. There is a plot beneath this first contact story, and beyond the political problem of figuring out what to do with Rose and the Tecran. Sazo, Rose's AI friend, does not want the Grih to know he exists. He has a history that Rose does not know about and may not be entirely safe. As the political situation with the Tecran escalates, Sazo is pursuing goals of his own, and Rose has a firm opinion about where her loyalties should lie. The resolution is nothing ground-breaking as far as SF goes, but I thought it was satisfyingly tense and complex. Dark Horse leaves obvious room for a sequel, but it comes to a satisfying conclusion. The writing is serviceable, particularly once you get into the story. I would not call it great, and it's not going to win any literary awards, but it didn't interfere with my enjoyment of the story. This is not the sort of book that will make anyone's award list, but it is easily in the top five of books I had the most fun reading this year. Maybe save it for when you're looking for something light and wholesome and don't mind some rather obvious tropes, but if you're in the mood for imagining people who take laws seriously and sincerely try to help other people, I found this an utterly delightful way to pass the time. I immediately bought the sequel. Recommended. Followed by Dark Deeds. Rating: 8 out of 10

Short version: Secure Boot Advanced Targeting and if that's enough for you you can skip the rest you're welcome.

Long version: When UEFI Secure Boot was specified, everyone involved was, well, a touch naive. The basic security model of Secure Boot is that all the code that ends up running in a kernel-level privileged environment should be validated before execution - the firmware verifies the bootloader, the bootloader verifies the kernel, the kernel verifies any additional runtime loaded kernel code, and now we have a trusted environment to impose any other security policy we want. Obviously people might screw up, but the spec included a way to revoke any signed components that turned out not to be trustworthy: simply add the hash of the untrustworthy code to a variable, and then refuse to load anything with that hash even if it's signed with a trusted key.

Unfortunately, as it turns out, scale. Every Linux distribution that works in the Secure Boot ecosystem generates their own bootloader binaries, and each of them has a different hash. If there's a vulnerability identified in the source code for said bootloader, there's a large number of different binaries that need to be revoked. And, well, the storage available to store the variable containing all these hashes is limited. There's simply not enough space to add a new set of hashes every time it turns out that grub (a bootloader initially written for a simpler time when there was no boot security and which has several separate image parsers and also a font parser and look you know where this is going) has another mechanism for a hostile actor to cause it to execute arbitrary code, so another solution was needed.

And that solution is SBAT. The general concept behind SBAT is pretty straightforward. Every important component in the boot chain declares a security generation that's incorporated into the signed binary. When a vulnerability is identified and fixed, that generation is incremented. An update can then be pushed that defines a minimum generation - boot components will look at the next item in the chain, compare its name and generation number to the ones stored in a firmware variable, and decide whether or not to execute it based on that. Instead of having to revoke a large number of individual hashes, it becomes possible to push one update that simply says "Any version of grub with a security generation below this number is considered untrustworthy".

So why is this suddenly relevant? SBAT was developed collaboratively between the Linux community and Microsoft, and Microsoft chose to push a Windows update that told systems not to trust versions of grub with a security generation below a certain level. This was because those versions of grub had genuine security vulnerabilities that would allow an attacker to compromise the Windows secure boot chain, and we've seen real world examples of malware wanting to do that (Black Lotus did so using a vulnerability in the Windows bootloader, but a vulnerability in grub would be just as viable for this). Viewed purely from a security perspective, this was a legitimate thing to want to do.

(An aside: the "Something has gone seriously wrong" message that's associated with people having a bad time as a result of this update? That's a message from shim, not any Microsoft code. Shim pays attention to SBAT updates in order to avoid violating the security assumptions made by other bootloaders on the system, so even though it was Microsoft that pushed the SBAT update, it's the Linux bootloader that refuses to run old versions of grub as a result. This is absolutely working as intended)

The problem we've ended up in is that several Linux distributions had not shipped versions of grub with a newer security generation, and so those versions of grub are assumed to be insecure (it's worth noting that grub is signed by individual distributions, not Microsoft, so there's no externally introduced lag here). Microsoft's stated intention was that Windows Update would only apply the SBAT update to systems that were Windows-only, and any dual-boot setups would instead be left vulnerable to attack until the installed distro updated its grub and shipped an SBAT update itself. Unfortunately, as is now obvious, that didn't work as intended and at least some dual-boot setups applied the update and that distribution's Shim refused to boot that distribution's grub.

What's the summary? Microsoft (understandably) didn't want it to be possible to attack Windows by using a vulnerable version of grub that could be tricked into executing arbitrary code and then introduce a bootkit into the Windows kernel during boot. Microsoft did this by pushing a Windows Update that updated the SBAT variable to indicate that known-vulnerable versions of grub shouldn't be allowed to boot on those systems. The distribution-provided Shim first-stage bootloader read this variable, read the SBAT section from the installed copy of grub, realised these conflicted, and refused to boot grub with the "Something has gone seriously wrong" message. This update was not supposed to apply to dual-boot systems, but did anyway. Basically:

1) Microsoft applied an update to systems where that update shouldn't have been applied
2) Some Linux distros failed to update their grub code and SBAT security generation when exploitable security vulnerabilities were identified in grub

The outcome is that some people can't boot their systems. I think there's plenty of blame here. Microsoft should have done more testing to ensure that dual-boot setups could be identified accurately. But also distributions shipping signed bootloaders should make sure that they're updating those and updating the security generation to match, because otherwise they're shipping a vector that can be used to attack other operating systems and that's kind of a violation of the social contract around all of this.

It's unfortunate that the victims here are largely end users faced with a system that suddenly refuses to boot the OS they want to boot. That should never happen. I don't think asking arbitrary end users whether they want secure boot updates is likely to result in good outcomes, and while I vaguely tend towards UEFI Secure Boot not being something that benefits most end users it's also a thing you really don't want to discover you want after the fact so I have sympathy for it being default on, so I do sympathise with Microsoft's choices here, other than the failed attempt to avoid the update on dual boot systems.

Anyway. I was extremely involved in the implementation of this for Linux back in 2012 and wrote the first prototype of Shim (which is now a massively better bootloader maintained by a wider set of people and that I haven't touched in years), so if you want to blame an individual please do feel free to blame me. This is something that shouldn't have happened, and unless you're either Microsoft or a Linux distribution it's not your fault. I'm sorry.

comments

Review: These Burning Stars, by Bethany Jacobs

Series:	Kindom Trilogy #1
Publisher:	Orbit
Copyright:	October 2023
ISBN:	0-316-46342-6
Format:	Kindle
Pages:	430

These Burning Stars is a science fiction thriller with cyberpunk vibes. It is Bethany Jacobs's first novel and the first of an expected trilogy, and won the 2024 Philip K. Dick Award for the best SF paperback original published in the US. Generation starships brought humanity to the three star systems of the Treble, where they've built a new and thriving culture of billions. The Treble is ruled by the Kindom, a tripartite government structure built around the worship of six gods and the aristocratic power of the First Families. The Clerisy handle religion, the Secretaries run the bureaucracy, and the Cloaksaan enforce the decisions of the other branches. The Nightfoots are one of the First Families. They control sevite, the propellant required to move between the systems of the Treble now that the moon Jeve and the sole source of natural jevite has been destroyed. Esek Nightfoot is a cleric, theoretically following the rules of the Clerisy, but she has made a career of training cloaksaan. She is is mercurial, powerful, ruthless, ambitious, politically well-connected, and greatly feared. She is also obsessed with a person named Six: an orphan she first encountered at a training school who was too young to have a gender or a name but who was already one of the best fighters in the school. In the sort of manipulative challenge typical of Esek, she dangled the offer of a place as a student and challenged the child to learn enough to do something impressive. The subsequent twenty years of elusive taunts and mysterious gifts from the impossible-to-locate Six have driven Esek wild. Cleric Chono was beside Esek for much of that time. One of Six's classmates and another of Esek's rescues, Chono is the rare student who became a cleric rather than a cloaksaan. She is pious, cautious, and careful, the opposite of Esek's mercurial rage, but it's impossible to spend that much time around the woman and not be affected and manipulated by her. As this story opens, Chono is summoned by the First Cleric to join Esek on an assignment: recover a data coin that was stolen from a pirate raid on the Nightfoot compound. He refuses to tell them what data is on it, only saying that he believes it could be used to undermine public trust in the Nightfoot family. Jun is a hacker with considerably fewer connections to power or government and no desire to meet any of these people. She and her partner Liis make a dubiously legal living from smaller, quieter jobs. Buying a collection of stolen data coins for an archivist consortium is riskier than she prefers, but she's been tracking down rumors of this coin for months. The deal is worth a lot of money, enough to make a huge difference for her family. This is the second book I've read recently with strong cyberpunk vibes, although These Burning Stars mixes them with political thriller. This is a messy world with complicated political and religious systems, a lot of contentious history, and vast inequality. The story is told in two interleaved time sequences: the present-day fight over the data coin and the information that it contains, and a sequence of flashbacks telling the history of Esek's relationship with Six and Chono. Jun's story is the most cyberpunk and the one I found the most enjoyable to read, but Chono is a good viewpoint character for Esek's vicious energy and abusive charisma. Six is not a viewpoint character. For most of the book, they're present mostly in shadows, glimpses, and consequences, but they're the strongest character of the book. Both Esek and Six are larger than life, creatures of legend stuffed into mundane politics but too full of strong emotions, both good and bad, to play by any of the rules. Esek has the power base and access to the levers of government, but Six's quiet competence and mercilessly targeted morality may make them the more dangerous of the pair. I found the twisty political thriller part of this book engrossing and very difficult to put down, but it was also a bit too much drama for me in places. Jacobs has some surprises in store, one of which I did not expect at all, and they're set up beautifully and well-done within the story, but Esek and Six become an emotional star that the other characters orbit around and are in danger of getting pulled into. Chono is an accomplished and powerful character in her own right, but she's also an abuse victim, and while those parts are realistic, I didn't entirely enjoy reading them. There is quiet competence here alongside the drama, but I think I wanted the balance of emotion to tip a bit more towards the competence. There is one thing that Jacobs does with the end of the book that greatly impressed me. Unfortunately I can't even hint at it for fear of spoilers, but the ending is unsettling in a way that I found surprising and thought-provoking. I think what I can say is that this book respects the intelligence and skill of secondary characters in a way that I think is rare in a story with such overwhelming protagonists. I'm still thinking about that, and it's going to pull me right into the sequel. This is not going to be to everyone's taste. Esek is a viewpoint character and she can be very nasty. There's a lot of violence and abuse, including one rather graphic fight scene that I thought dragged on much longer than it needed to. But it's a satisfying, complex story with a true variety of characters and some real surprises. I'm glad I read it. Followed by On Vicious Worlds, not yet published as I write this. Content warnings: emotional and physical abuse, graphic violence, off-screen rape and sexual abuse of minors. Rating: 7 out of 10

On Saturday 3 August 2024, the annual Debian Developers and Contributors Conference came to a close. Over 339 attendees representing 48 countries from around the world came together for a combined 108 events made up of more than 50 Talks and Discussions, 37 Birds of a Feather (BoF informal meeting between developers and users) sessions, 12 workshops, and activities in support of furthering our distribution and free software (25 patches submitted to the Linux kernel), learning from our mentors and peers, building our community, and having a bit of fun. The conference was preceded by the annual DebCamp hacking session held July 21st through July 27th where Debian Developers and Contributors convened to focus on their Individual Debian-related projects or work in team sprints geared toward in-person collaboration in developing Debian. This year featured a BootCamp that was held for newcomers with a GPG Workshop and a focus on Introduction to creating .deb files (Debian packaging) staged by a team of dedicated mentors who shared hands-on experience in Debian and offered a deeper understanding of how to work in and contribute to the community. The actual Debian Developers Conference started on Sunday July 28 2024. In addition to the traditional 'Bits from the DPL' talk, the continuous key-signing party, lightning talks and the announcement of next year's DebConf25, there were several update sessions shared by internal projects and teams. Many of the hosted discussion sessions were presented by our technical core teams with the usual and useful meet the Technical Committee and the ftpteam and a set of BoFs about packaging policy and Debian infrastructure, including talk about APT and Debian Installer and an overview about the first eleven years of Reproducible Builds. Internationalization and localization have been subject of several talks. The Python, Perl, Ruby, and Go programming language teams, as well as Med team, also shared updates on their work and efforts. More than fifteen BoFs and talks about community, diversity and local outreach highlighted the work of various team involved in the social aspect of our community. This year again, Debian Brazil shared strategy and action to attract and retain new contributors and members and opportunities both in Debian and F/OSS. The schedule was updated each day with planned and ad-hoc activities introduced by attendees over the course of the conference. Several traditional activities took place: a job fair, a poetry performance, the traditional Cheese and Wine party, the group photos and the Day Trips. For those who were not able to attend, most of the talks and sessions were broadcast live and recorded and the videos made available through a link in their summary in the schedule. Almost all of the sessions facilitated remote participation via IRC messaging apps or online collaborative text documents which allowed remote attendees to 'be in the room' to ask questions or share comments with the speaker or assembled audience. DebConf24 saw over 6.8 TiB (4.3 TiB in 2023) of data streamed, 91.25 hours (55 in 2023) of scheduled talks, 20 network access points, 1.6 km fibers (1 broken fiber...) and 2.2 km UTP cable deployed, more than 20 country Geoip viewers, 354 T-shirts, 3 day trips, and up to 200 meals planned per day. All of these events, activities, conversations, and streams coupled with our love, interest, and participation in Debian and F/OSS certainly made this conference an overall success both here in Busan, South Korea and online around the world. The DebConf24 website will remain active for archival purposes and will continue to offer links to the presentations and videos of talks and events. Next year, DebConf25 will be held in Brest, France, from Monday, July 7 to Monday, July 21, 2025. As tradition follows before the next DebConf the local organizers in France will start the conference activities with DebCamp with particular focus on individual and team work towards improving the distribution. DebConf is committed to a safe and welcome environment for all participants. See the web page about the Code of Conduct in DebConf24 website for more details on this. Debian thanks the commitment of numerous sponsors to support DebConf24, particularly our Platinum Sponsors: Infomaniak, Proxmox, and Wind River. We also wish to thank our Video and Infrastructure teams, the DebConf24 and DebConf committees, our host nation of South Korea, and each and every person who helped contribute to this event and to Debian overall. Thank you all for your work in helping Debian continue to be "The Universal Operating System". See you next year! About Debian The Debian Project was founded in 1993 by Ian Murdock to be a truly free community project. Since then the project has grown to be one of the largest and most influential open source projects. Thousands of volunteers from all over the world work together to create and maintain Debian software. Available in 70 languages, and supporting a huge range of computer types, Debian calls itself the universal operating system. About DebConf DebConf is the Debian Project's developer conference. In addition to a full schedule of technical, social and policy talks, DebConf provides an opportunity for developers, contributors and other interested people to meet in person and work together more closely. It has taken place annually since 2000 in locations as varied as Scotland, Argentina, Bosnia and Herzegovina, and India. More information about DebConf is available from https://debconf.org/. About Infomaniak Infomaniak is an independent cloud service provider recognized throughout Europe for its commitment to privacy, the local economy and the environment. Recording growth of 18% in 2023, the company is developing a suite of online collaborative tools and cloud hosting, streaming, marketing and events solutions. Infomaniak uses exclusively renewable energy, builds its own data centers and develops its solutions in Switzerland, without relocating. The company powers the website of the Belgian radio and TV service (RTBF) and provides streaming for more than 3,000 TV and radio stations in Europe. About Proxmox Proxmox provides powerful and user-friendly Open Source server software. Enterprises of all sizes and industries use Proxmox solutions to deploy efficient and simplified IT infrastructures, minimize total cost of ownership, and avoid vendor lock-in. Proxmox also offers commercial support, training services, and an extensive partner ecosystem to ensure business continuity for its customers. Proxmox Server Solutions GmbH was established in 2005 and is headquartered in Vienna, Austria. Proxmox builds its product offerings on top of the Debian operating system. About Wind River Wind River For nearly 20 years, Wind River has led in commercial Open Source Linux solutions for mission-critical enterprise edge computing. With expertise across aerospace, automotive, industrial, telecom, and more, the company is committed to Open Source through initiatives like eLxr, Yocto, Zephyr, and StarlingX. Contact Information For further information, please visit the DebConf24 web page at https://debconf24.debconf.org/ or send mail to press@debian.org.

Planing A Self Organized Solo Trip You know the movie Queen? The actor Kangana Ranaut plays in that movie the role of Rani Mehra, a 24-year-old Punjabi woman, who was a simple, homely girl that was always reliant on her family. Similar to Rani I too rarely ventured out without my parents and often needed my younger sibling by my side. Inspired by her transformation, I decided it was time to take control of my own story and discover who I truly am.

Trip Requirements

My First Passport The journey began with a significant first step: Obtaining my first passport Never having had one before, I scheduled the nearest available interview date on June 29 2022. This meant traveling to Solapur, a city 309 km from my hometown, accompanied by my father. After successfully completing the interview, I received my passport on July 14 2022.

Select A Country, Booking Flights And Accommodation Excited and ready to embark on my adventure, I planed trip to Albania and booked the flight tickets. Why? I had heard from friends that it was a beautiful European country with beaches and other attractions, and importantly, it didn t require a visa for Indian citizens and was more affordable than other European destinations. Before heading to Albania, I planned a overnight stop in Abu Dhabi with a transit visa, thanks to friend who knew the process for obtaining it. Some of my friends did travel also to Europe at the same time and quite close to my plannings, but that I realized just later the trip.

Day 1, Starting The Experience On July 20, 2022, I started my journey by traveling from Pune, Maharashtra, to Delhi, where my brother lives. He came to see me off at the airport, adding a touch of warmth and support to the beginning of my solo adventure. Upon arriving in Delhi, with my next flight scheduled for July 21, I stayed at a backpacker hostel named Zostel, Paharganj, Delhi to rest. During my stay, I noticed that many travelers at the hostel carried rucksacks, which sparked a desire in me to get one for my own trip to Europe. Up until then, I had always shopped with my mom and had never bought anything on my own. Inspired by the travelers, I set out to find a suitable rucksack. I traveled alone by metro from Paharganj to Rohini to visit a Decathlon store, where I purchased a 50-liter rucksack. This was a significant step in preparing for my European adventure and marked a milestone in my journey of self reliance.

Day 2, Flying To Abu Dhabi The following day, July 21 2024, I had a flight to Abu Dhabi. I spent the night at the hostel to rest before my journey. On the day of the flight, I needed to reach the airport by 3 PM, and a friend kindly came to drop me off. With my rucksack packed and excitement building, I was ready for the next leg of my adventure. When we arrived at the airport, my friend saw me off, marking the start of my international journey. With mom made spices, chutneys, and chilly flakes packed for comfort, I completed my immigration process in about two and a half hours. I then settled at the gate for my flight, feeling a mix of excitement and anxiety as thoughts raced through my mind. To ease my nerves, I struck up a conversation with a man seated nearby who was also traveling to Abu Dhabi for work. He provided helpful information about safety and transportation in Abu Dhabi, which reassured me. With the boarding process complete and my anxiety somewhat eased. I found my window seat on the flight and settled in, excited for the journey ahead. Next to me was a young man from Ranchi(Zarkhand, India), heading to Abu Dhabi for work at a mining factory. We had an engaging conversation about work culture in Abu Dhabi and recruitment from India. Upon arriving in Abu Dhabi, I completed my transit, collected my luggage, and began finding my way to the hotel Premier Inn AbuDhabi, which was in the airport area. To my surprise, I ran into the same man from the flight, now in a cab. He kindly offered to drop me at my hotel, which I gladly accepted since navigating an unfamiliar city with a short acquaintance felt safer. At the hotel gate, he asked if I had local currency (Dirhams) for payment, as sometimes online transactions can fail. That hadn t crossed my mind, and I realized I might be left stranded if a transaction failed. Recognizing his help as a godsend, I asked if he could lend me some Dirhams, promising to transfer the amount later. He kindly assured me to pay him back once I reached the hotel room. With that relief, I checked into the hotel, feeling deeply grateful for the unexpected assistance and transferred the money to him after getting to my room.

Day 3, Flying And Arrive In Tirana Once in the hotel room, I found it hard to sleep, anxious about waking up on time for my flight. I set an alarm to wake up early, but my subconscious mind kept me alert, and I woke up before the alarm went off. I got freshened up and went down for breakfast, where I found some vegetarian options like Idli-Sambar and bread with butter, along with some morning tea. After breakfast, I headed back to the airport, ready to catch my flight to my final destination: Tirana, Albania. I reached Tirana, Albania after a six hours flight, feeling exhausted and I was suffering from a headache. The air pressure had blocked my ears, and jet lag added to my fatigue. After collecting my checked luggage, I headed to the first ATM machine at the airport. Struggling to insert my card, I asked a nearby gentleman for help. He tried his best, but my card got stuck inside the machine. Panic set in as I worried about how I would survive without money. Taking a deep breath, I found an airport employee and explained the situation. The gentleman stayed with me, offering support and repeatedly apologizing for his mistake. However, it wasn t his fault, the ATM was out of order, which I hadn t noticed. My focus was solely on retrieving my ATM card. The airport employee worked diligently, using a hairpin to carefully extract my card. Finally, the card was freed, and I felt an immense sense of relief, grateful for the help of these kind strangers. I used another ATM, successfully withdrew money, and then went to an airport mobile SIM shop to buy a new SIM card for local internet and connectivity.

Day 4, Arriving In Tirana, Facing Challenges In A Foreign Country I had booked a stay at a backpacker hostel near the city center of Tirana. After sorting out the ATM and SIM card issues, I searched for a bus or any transport to get there. It was quite late, around 8:30 PM, and being in a new city, I was in a hurry. I saw a bus nearly leaving the airport, stopped it, and asked if it went to the city center. They gave me the green flag, so I boarded the airport service bus and reached the city center. Feeling very tired, I discovered that the hostel was about an hour and a half away by walking. Deciding to take a cab, I faced a challenge as the driver couldn t understand my English or accent. Using a mobile translator to convert my address from English to Albanian, I finally communicated my destination to him. With that sorted out, I headed to the Blue Door Backpacker Hostel and arrived around 9 PM, relieved to have finally reached my destination and I checked in. I found my top bunk bed, only to realize I had booked a mixed-gender dormitory. This detail had completely escaped my notice during the booking process. I felt unsure about how to handle the situation. Coincidentally, my experience mirrored what Kangana faced in the movie Queen . Feeling acidic due to an empty stomach and the exhaustion of heavy traveling, I wasn t up to cooking in the hostel s kitchen. I asked the front desk about the nearest restaurant. It was nearly 9:30 PM, and the streets were deserted. To avoid any mishaps like in the movie Queen, I kept my passport securely locked in my bag, ensuring it wouldn t be a victim of theft. Venturing out for dinner, I felt uneasy on the quiet streets. I eventually found a restaurant recommended by the hostel, but the menu was almost entirely non-vegetarian. I struggled to ask about vegetarian options and was uncertain if any dishes contained eggs, as some people consider eggs to be vegetarian. Feeling frustrated and unsure, I left the restaurant without eating. I noticed a nearby grocery store that was about to close and managed to get a few extra minutes to shop. I bought some snacks, wafers, milk, and tea bags (though I couldn t find tea powder to make Indian-style tea). Returning to the hostel, I made do with wafers, cookies, and milk for dinner. That day was incredibly tough for me, I filled with exhaustion and struggle in a new country, I was on the verge of tears . I made a video call home before sleeping on the top bunk bed. It was a new experience for me, sharing a room with both unknown men and women. I kept my passport safe inside my purse and under my pillow while sleeping, staying very conscious about its security.

Day 5, Exploring Nearby Places I woke up the next day at noon. After having some coffee, the hostel management girl asked if I wanted breakfast. She offered curd with cornflakes, which I refused because I don t like curd. Instead, I ordered a pizza from a vegetarian pizza place with her help, and I started feeling better. I met some people in the hostel, some from Syria and others from Italy. I struggled to understand their accents but kept pushing myself to get involved in their discussions. Despite the challenges, I felt more at ease and was slowly adapting to my new environment. I went out from the hostel in the evening to buy some vegetables to cook something. I searched for shops and found some potatoes, tomatoes, and rice. I decided to cook Khichdi, an Indian dish made with rice, and added some chili flakes I brought from home. After preparing my dinner, I ate and then went to sleep again.

Day 6, Tiranas Recent History The next day, I planned to explore the city and visited Bunkart-1, a fascinating museum in a massive underground bunker from the communist era. Originally built as a shelter for Albania s political and military elite, it now offers a unique glimpse into the country s history under Enver Hoxha s oppressive regime. The museum s exhibits include historical artifacts, photographs, and multimedia displays that detail the lives of Albanians during that time. Walking through the dimly lit corridors, I felt the weight of history and gained a deeper understanding of Albania s past.

Day 7-8, Meeting Friends From India The next day, I accidentally met with Chirag, who was returning from the Debian Conference 2022 held in Prizren, Kosovo, and staying at the same hostel. When I encountered him, he was talking on the phone, and I recognized he was Indian by his accent. I introduced myself, and we discovered we had some mutual friends. Chirag told me that our common friend, Raju, was also coming to stay at the hostel the next day. This news made me feel relaxed and happy to have known people around. When Raju arrived, the three of us, Chirag, Raju, and I planned to have dinner at an Indian restaurant and explore Tirana city. I had a great time talking and enjoying their company.

Day 9-10, Meeting More Friends Raju had a ticket to leave soon, so Chirag and I made a plan to visit Shkod r and the nearby Komani Lake for kayaking. We started our journey early in the morning by bus and reached Shkod r. There, we met new friends from the conference, Pavit and Abraham, who were already there. We had dinner together and enjoyed an ice cream treat from Chirag.

Day 12, Kayaking And Say Good Bye To Friends The next day, Pavit and Abraham had a flight back to India, so Chirag and I went to Komani Lake. We had an adventurous time kayaking, even though neither of us knew how to swim. We took a ferry through the backwaters to the island on Komani Lake and enjoyed a fantastic adventure together. After our trip, Chirag returned to Tirana for his flight back to India, leaving me to continue my journey alone.

Day 13, Climbing Rozafa Castel By stopping at Shkod r, I visited Rozafa Castle. Despite the language barrier, as most locals only spoke Albanian, people around me guided me correctly on how to get there. At times, I used applications like Google Translate to communicate. To read signs or hotel menus, I used Google Photos' language converter. I even used the audio converter to understand and speak some basic Albanian phrases. I took a bus from Shkod r to the southern part of Albania, heading to Sarand . The journey lasted about five to six hours, and I had booked a stay at Mona s Hostel. Upon arrival, I met Eliza from America, and we went together to Ksamil Beach, spending a wonderful day there.

Day 14, Vlora Beach: Beach Side Cycling Next, I traveled to Vlor , where I stayed for one day. During my time there, I enjoyed beach side cycling with a cycle provided by the hostel owner and spent some time feeding fish. I also met a fellow traveler from Delhi who had brought along some preserved Indian curry. He kindly shared it with me, which was a welcome change after nearly 15 days without authentic Indian cuisine, except for what I had cooked myself in various hostels.

Day 15-16 Visiting Durress, Travelling Back To Tirana I then visited Durr s, exploring its beautiful beaches, before heading back to Tirana one day before my flight home. On the day of my flight, my alarm didn t go off, and I woke up late at the hostel. In a frantic rush, I packed everything in just five minutes and dashed toward the city center to catch the bus to the airport. If I had been just five minutes later, I would have missed the bus. Thankfully, I managed to stop it just in time and began my journey back home, reflecting on the incredible adventure I had experienced. Fortunately, I wasn t late; I arrived at the airport just in time. After clearing immigration, I boarded my flight, which had a layover in Warsaw, Poland. The journey from Tirana to Warsaw took about two and a half hours, followed by a seven to eight-hour flight from Poland back to India. Once I arrived in Delhi, I returned to Zostel and booked a train ticket to Aurangabad for the next three days.

Backview This trip was an incredible adventure for me. I never imagined I could accomplish something like this, but I did. Meeting diverse people, experiencing different cultures, and learning so much made this journey truly unforgettable. Looking back, I realize how much I ve grown from this experience. Although I may have more opportunities to travel abroad in the future, this trip will always hold a special place in my heart. The memories I made and the incredible people I met along the way are irreplaceable. This experience goes beyond what I can express through this blog or words; it was incredibly precious to me. Every moment of this journey is etched in my memory, and I am grateful for every part of it.

I m finishing typing up this blog entry hours before my last 13 hour leg back home, after I spent 2 weeks in Busan, South Korea for DebCamp24 and DebCamp24. I had a rough year and decided to take it easy this DebConf. So this is the first DebConf in a long time where I didn t give any talks. I mostly caught up on a bit of packaging, worked on DebConf video stuff, attended a few BoFs and talked to people. Overall it was a very good DebConf, which also turned out to be more productive than I expeced it would. In the welcome session on the first day of DebConf, Nicolas Dandrimont mentioned that a benefit of DebConf is that it provides a sort of caffeine for your Debian motivation. I could certainly feel that affect swell as the days went past, and it s nice to be excited about some ideas again that would otherwise be fading.

Recovering DPL It s a bit of a gear shift being DPL for 4 years, and DebConf Committee for nearly 5 years before that, and then being at DebConf while some issue arise (as it always does during a conference). At first I jump into high alert mode, but then I have to remind myself it s not your problem anymore and let others deal with it. It was nice spending a little in-person time with Andreas Tille, our new DPL, we did some more handover and discussed some current issues. I still have a few dozen emails in my DPL inbox that I need to collate and forward to Andreas, I hope to finish all that up by the end of August. During the Bits from the DPL talk, the usual question came up whether Andreas will consider running for DPL again, to which he just responded in a slide Maybe . I think it s a good idea for a DPL to do at least two terms if it all works out for everyone, since it takes a while to get up to speed on everything. Also, having been DPL for four years, I have a lot to say about it, and I think there s a lot we can fix in the role, or at least discuss it. If I had the bandwidth for it I would have scheduled a BoF for it, but I ll very likely do that for the next DebConf instead!

Video team I set up the standby loop for the video streaming setup. We call it loopy, it s a bunch of OBS scenes that provide announcements, shows sponsors, the schedule and some social content. I wrote about it back in 2020, but it s evolved quite a bit since then, so I m probably due to write another blog post with a bunch of updates on it. I hope to organise a video team sprint in Cape Town in the first half of next year, so I ll summarize everything before then.

It would ve been great if we could have some displays in social areas that could show talks, the loop and other content, but we were just too pressed for time for that. This year s DebConf had a very compressed timeline, and there was just too much that had to be done and that had to be figured out on the last minute. This put quite a lot of strain on the organisers, but I was glad to see how, for the most part, most attendees were very sympathetic to some rough edges (but I digress ). I added more of the OBS machine setup to the videoteam s ansible repository, so as of now it just needs an ansible setup and the OBS data and it s good to go. The loopy data is already in the videoteam git repository, so I could probably just add a git pull and create some symlinks in ansible and then that machine can be installed from 0% to 100% by just installing via debian-installer with our ansible hooks. This DebConf I volunteered quite a bit for actual video roles during the conference, something I didn t have much time for in recent DebConfs, and it s been fun, especially in a session or two where nearly none of the other volunteers showed up. Sometimes chaos is just fun :-)

Baekyongee is the university mascot, who s visible throughout the university. So of course we included this four legged whale creature on the loop too!

Packaging I was hoping to do more packaging during DebCamp, but at least it was a non-zero amount:

• Uploaded gdisk 1.0.10-2 to unstable (previously tested effects of adding dh-sequence-movetousr) (Closes: #1073679).
• Worked a bit on bcachefs-tools (updating git to 1.9.4), but has a build failure that I need to look into (we might need a newer bindgen) update: I m probably going to ROM this package soon, it doesn t seem suitable for packaging in Debian.
• Calamares: Tested a fix for encrypted installs, and uploaded it.
• Calamares: Uploaded (3.3.8-1) to backports (at the time of writing it s still in backports-NEW).
• Backport obs-gradient-source for bookworm.
• Did some initial packaging on Cambalache, I ll upload to unstable once wlroots (0.18) hits unstable.
• Pixelorama 1.0 I did some initial packaging for Pixelorama back when we did the MiniDebConf Gaming Edition, but it had a few stoppers back then. Version 1.0 seems to fix all of that, but it depends on Godot 4.2 and we re still on the 3 series in Debian, so I ll upload this once Godot 4.2 hits at least experimental. Godot software/games is otherwise quite easy to run, it s basically just source code / data that is installed and then run via godot-runner (godot3-runner package in Debian).

BoFs Python Team BoF Link to the etherpad / pad archive link and video can be found on the talk page: https://debconf24.debconf.org/talks/31-python-bof/ The session ended up being extended to a second part, since all the issues didn t fit into the first session. I was distracted by too many thing during the Python 3.12 transition (to the point where I thought that 3.11 was still new in Debian), so it was very useful listening to the retrospective of that transition. There was a discussion whether Python 3.13 could still make it to testing in time for freeze, and it seems that there is consensus that it can, although, likely with new experimental features like disabling the global interpreter lock and the just in time compiler disabled. I learned for the first time about the dead batteries project, PEP-0594, which removes ancient modules that have mostly been superseded, from the Python standard library. There was some talk about the process for changing team policy, and a policy discussion on whether we should require autopkgtests as a SHOULD or a MUST for migration to testing. As with many things, the devil is in the details and in my opinion you could go either way and achieve a similar result (the original MUST proposal allowed exceptions which imho made it the same as the SHOULD proposal). There s an idea to do some ongoing remote sprints, like having co-ordinated days for bug squashing / working on stuff together. This is a nice idea and probably a good way to energise the team and also to gain some interest from potential newcomers. Louis-Philipe V ronneau was added as a new team admin and there was some discussion on various Sphinx issues and which Lintian tags might be needed for Python 3.13. If you want to know more, you probably have to watch the videos / read the notes :)

Debian.net BoF Link to the etherpad / pad archive link can be found on the talk page: https://debconf24.debconf.org/talks/37-debiannet-team-bof Debian Developers can set up services on subdomains on debian.net, but a big problem we ve had before was that developers were on their own for hosting those services. This meant that they either hosted it on their DSL/fiber connection at home, paid for the hosting themselves, or hosted it at different services which became an accounting nightmare to claim back the used funds. So, a few of us started the debian.net hosting project (sometimes we just call it debian.net, this is probably a bit of a bug) so that Debian has accounts with cloud providers, and as admins we can create instances there that gets billed directly to Debian. We had an initial rush of services, but requests have slowed down since (not really a bad thing, we don t want lots of spurious requests). Last year we did a census, to check which of the instances were still used, whether they received system updates and to ask whether they are performing backups. It went well and some issues were found along the way, so we ll be doing that again. We also gained two potential volunteers to help run things, which is great. Debian Social BoF Link to the etherpad / pad archive link can be found on the talk page: https://debconf24.debconf.org/talks/34-debiansocial-bof We discussed the services we run, you can view the current state of things at: https://wiki.debian.org/Teams/DebianSocial Pleroma has shown some cracks over the last year or so, and there are some forks that seem promising. At the same time, it might be worth while considering Mastodon too. So we ll do some comparison of features and maintenance and find a way forward. At the time when Pleroma was installed, it was way ahead in terms of moderation features. Pixelfed is doing well and chugging along nicely, we should probably promote it more. Peertube is working well, although we learned that we still don t have all the recent DebConf videos on there. A bunch of other issues should be fixed once we move it to a new machine that we plan to set up. We re removing writefreely and plume. Nice concepts, but it didn t get much traction yet, and no one who signed up for these actually used it, which is fine, some experimentation with services is good and sometimes they prove to be very popular and other times not. The WordPress multisite instance has some mild use, otherwise haven t had any issues. Matrix ended up to be much, much bigger than we thought, both in usage and in its requirements. It s very stateful and remembers discussions for as long as you let it, so it s Postgres database is continuously expanding, this will also be a lot easier to manage once we have this on the new host. Jitsi is also quite popular, but it could probably be on jitsi.debian.net instead (we created this on debian.social during the initial height of COVID-19 where we didn t have the debian.net hosting yet), although in practice it doesn t really matter where it lives. Most of our current challenges will be solved by moving everything to a new big machine that has a few public IPs available for some VMs, so we ll be doing that shortly. Debian Foundation Discussion BoF This was some brainstorming about the future structure of Debian, and what steps might be needed to get there. It s way too big a problem to take on in a BoF, but we made some progress in figuring out some smaller pieces of the larger puzzle. The DPL is going to get in touch with some legal advisors and our trusted organisations so that we can aim to formalise our relationships a bit more by the time it s DebConf again. I also introduced my intention to join the Debian Partners delegation. When I was DPL, I enjoyed talking with external organisations who wanted to help Debian, but helping external organisations help Debian turned out to be too much additional load on the usual DPL roles, so I m pursuing this with the Debian Partners team, more on that some other time. This session wasn t recorded, but if you feel like you missed something, don t worry, all intentions will be communicated and discussed with project members before anything moves forward. There was a strong agreement in the room though that we should push forward on this, and not reach another DebConf where we didn t make progress on formalising Debian s structure more.

Social Conference Dinner

Conference Dinner Photo from Santiago

The conference dinner took place in the university gymnasium. I hope not many people do sports there in the summer, because it got HOT. There was also some interesting observations on the thermodynamics of the attempted cooling solutions, which was amusing. On the plus side, the food was great, the company was good, and the speeches were kept to a minimum, so it was a great conference dinner, even though it was probably cut a bit short due to the heat. Cheese and Wine Cheese and Wine happened on 1 August, which happens to be the date I became a DD at DebConf17 in Montr al seven years before, so this was a nice accidental celebration of my Debiversary :) Since I m running out of time, I ll add some more photos to this post some time after publishing it :P Group Photo As per DebConf tradition, Aigars took the group photo. You can find the high resolution version on Debian s GitLab instance.

Debian annual conference Debconf 24, Busan, South Korea
Photography: Aigars Mahinovs aigarius@debian.org
License: CC-BYv3+ or GPLv2+

Talking Ah yes, talking to people is a big part of DebConf, but I didn t keep track of it very well.

• I mostly listened to Alper a bit about his ideas for his talk about debian installer.
• I talked to Rhonda a bit about ActivityPub and MQTT and whether they could be useful for publicising Debian activity.
• Listened to Gunnar and Julian have a discussion about GPG and APT which was interesting.
• I learned that you can learn Hangul, the Korean alphabet, in about an hour or so (I wish I knew that in all my years of playing StarCraft II).
• We had the usual continuous keysigning party. Besides it s intended function, this is always a good ice breaker and a way to for shy people to meet other shy people.
• and many other fly-by discussions.

Stuff that didn t happen this DebConf

• loo.py A simple Python script that could eventually replace the obs-advanced-scene-switcher sequencer in OBS. It would also be extremely useful if we d ever replace OBS for loopy. I was hoping to have some time to hack on this, and try to recreate the current loopy in loo.py, but didn t have the time.
• toetally This year videoteam had to scramble to get a bunch of resistors to assemble some tally light. Even when assembled, they were a bit troublesome. It would ve been nice to hack on toetally and get something ready for testing, but it mostly relies on having something like a rasbperry pi zero with an attached screen in order to work on further. I ll try to have something ready for the next mini conf though.
• extrepo on debian live I think we should have extrepo installed by default on desktop systems, I meant to start a discussion on this, but perhaps it s just time I go ahead and do it and announce it.
• Live stream to peertube server It would ve been nice to live stream DebConf to PeerTube, but the dependency tree to get this going got a bit too huge. Following our plans discussed in the Debian Social BoF, we should have this safely ready before the next MiniDebConf and should be able to test it there.
• Desktop Egg there was this idea to get a stand-in theme for Debian testing/unstable until the artwork for the next release is finalized (Debian bug: #1038660), I have an idea that I meant to implement months ago, but too many things got in the way. It s based on Juliette Taka s Homeworld theme, and basically transforms the homeworld into an egg. Get it? Something that hasn t hatched yet? I also only recently noticed that we never used the actual homeworld graphics (featuring the world image) in the final bullseye release. lol.

So, another DebConf and another new plush animal. Last but not least, thanks to PKNU for being such a generous and fantastic host to us! See you again at DebConf25 in Brest, France next year!

Review: The Book That Wouldn't Burn, by Mark Lawrence

Series:	Library Trilogy #1
Publisher:	Ace
Copyright:	2023
ISBN:	0-593-43793-4
Format:	Kindle
Pages:	561

The Book That Wouldn't Burn is apparently high fantasy, but of the crunchy sort that could easily instead be science fiction. It is the first of a trilogy. Livira is a young girl, named after a weed, who lives in a tiny settlement in the Dust. She is the sort of endlessly curious and irrepressible girl who can be more annoying than delightful to adults who are barely keeping everyone alive. Her settlement is not the sort of place that's large enough to have a name; only their well keeps them alive in the desert and the ever-present dust. There is a city somewhere relatively near, which Livira dreams of seeing, but people from the settlement don't go there. When someone is spotted on the horizon approaching the settlement, it's the first time Livira has ever seen a stranger. It's also not a good sign. There's only one reason for someone to seek them out in the Dust: to take. Livira and the other children are, in short order, prisoners of the humanoid dog-like sabbers, being dragged off to an unknown fate. Evar lives in the library and has for his entire life. Specifically, he lives in a square room two miles to a side, with a ceiling so high that it may as well be a stone sky. He lived there with his family before he was lost in the Mechanism. Years later, the Mechanism spit him out alongside four other similarly-lost kids, all from the same library in different times. None of them had apparently aged, but everyone else was dead. Now, years later, they live a strange and claustrophobic life with way too much social contact between way too few people. Evar's siblings, as he considers them, were each in the Mechanism with a book. During their years in the Mechanism they absorbed that book until it became their focus and to some extent their personality. His brothers are an assassin, a psychologist, and a historian. His sister, the last to enter the Mechanism and a refugee from the sabber attack that killed everyone else, is a warrior. Evar... well, presumably he had a book, since that's how the Mechanism works. But he can't remember anything about it except the feeling that there was a woman. Evar lives in a library in the sense that it's a room full of books, but those books are not on shelves. They're stacked in piles and massive columns, with no organizational system that any of them could discern. There are four doors, all of which are closed and apparently impenetrable. In front of one of them is a hundred yards of char and burned book remnants, but that door is just as impenetrable as the others. There is a pool in the center of the room, crops surrounding it, and two creatures they call the Soldier and the Assistant. That is the entirety of Evar's world. As you might guess from the title, this book is about a library. Evar's perspective of the library is quite odd and unexplained until well into the book, and Livira's discovery of the library and subsequent explorations are central to her story, so I'm going to avoid going into too many details about its exact nature. What I will say is that I have read a lot of fantasy novels that are based around a library, but I don't think I've ever read one that was this satisfying. I think the world of The Book That Wouldn't Burn is fantasy, in that there are fundamental aspects of this world that don't seem amenable to an explanation consistent with our laws of physics. It is, however, the type of fantasy with discoverable rules. Even better, it's the type of fantasy where discovering the rules is central to the story, for both the characters and the readers, and the rules are worth the effort. This is a world-building tour de force: one of the most engrossing and deeply satisfying slow revelations that I have read in a long time. This book is well over 500 pages, the plot never flags, new bits of understanding were still slotting into place in the last chapter, and there are lots of things I am desperately curious about that Lawrence left for the rest of the series. If you like puzzling out the history and rules of an invented world and you have anything close to my taste in characters and setting, you are going to love this book. (Also, there is at least one C.S. Lewis homage that I will not spoil but that I thought was beautifully done and delightfully elaborated, and I am fairly sure there is a conversation happening between this book and Philip Pullman's His Dark Materials series that I didn't quite untangle but that I am intrigued by.) I do need to offer a disclaimer: Livira is precisely the type of character I love reading about. She's stubborn, curious, courageous, persistent, egalitarian, insatiable, and extremely sharp. I have a particular soft spot for exactly this protagonist, so adjust the weight of my opinion accordingly. But Lawrence also makes excellent use of her as a spotlight to illuminate the world-building. More than anything else in the world, Livira wants to understand, and there is so much here to understand. There is an explanation for nearly everything in this book, and those explanations usually both make sense and prompt more questions. This is such a tricky balance for the writer to pull off! A lot of world-building of this sort fails either by having the explanations not live up to the mysteries or by tying everything together so neatly that the stakes of the world collapse into a puzzle box. Lawrence avoids both failures. This world made sense to me but remained sufficiently messy to feel like humans were living in it. I also thought the pacing and timing were impeccable: I figured things out at roughly the same pace as the characters, and several twists and turns caught me entirely by surprise. I do have one minor complaint and one caveat. The minor complaint is that I thought one critical aspect of the ending was a little bit too neat and closed. It was the one time in the book where I thought Lawrence simplified his plot structure rather than complicated it, and I didn't like the effect it had on the character dynamics. There is, thankfully, the promise of significant new complications in the next book. The caveat is a bit harder to put my finger on, but a comparison to Alaya Dawn Johnson's The Library of Broken Worlds might help. That book was also about a library, featured a protagonist thrown into the deep end of complex world-building, and put discovery of the history and rules at the center of the story. I found the rules structure of The Book That Wouldn't Burn more satisfyingly complicated and layered, in a way that made puzzle pieces fit together in my head in a thoroughly enjoyable way. But Johnson's book is about very large questions of identity, history, sacrifice, and pain, and it's full of murky ambiguity and emotions that are only approached via metaphor and symbolism. Lawrence's book is far more accessible, but the emotional themes are shallower and more straightforward. There is a satisfying emotional through-line, and there are some larger issues at stake, but it won't challenge your sense of morality and justice the way that The Library of Broken Worlds might. I think which of those books one finds better will depend on what mood you're in and what reading experience you're looking for. Personally, I was looking for a scrappy, indomitable character who would channel her anger into overcoming every obstacle in the way of thoroughly understanding her world, and that's exactly what I got. This was my most enjoyable reading experience of the year to date and the best book I've read since Some Desperate Glory. Fantastic stuff, highly recommended. Followed by The Book That Broke the World, and the ending is a bit of a cliffhanger so you may want to have that on hand. Be warned that the third book in the series won't be published until 2025. Rating: 9 out of 10