Search Results: "cas"

9 August 2025

Bits from Debian: Debian stable is now Debian 13 "trixie"!

Alt trixie has been released We are pleased to announce the official release of Debian 13, codenamed trixie! What's New in Debian 13 Want to install it? Fresh installation ISOs are now available, including the final Debian Installer featuring kernel 6.12.38 and mirror improvements. Choose your favourite installation media and read the installation manual. You can also use an official cloud image directly on your cloud provider, or try Debian prior to installing it using our "live" images. Already a happy Debian user and you only want to upgrade? Full upgrade path from Debian 12 "bookworm" is supported and documented in the Release Notes. Upgrade notes cover APT source preparation, handling obsoletes, and ensuring system resilience. Additional Information For full details, including upgrade instructions, known issues, and contributors, see the official Release Notes for Debian 13 "trixie". Congratulations to all developers, QA testers, and volunteers who made Debian 13 "trixie" possible! Do you want to celebrate the release? To celebrate with us on this occassion find a release party near to you and if there isn't any, organize one!

6 August 2025

Reproducible Builds: Reproducible Builds in July 2025

Welcome to the seventh report from the Reproducible Builds project in 2025. Our monthly reports outline what we ve been up to over the past month, and highlight items of news from elsewhere in the increasingly-important area of software supply-chain security. If you are interested in contributing to the Reproducible Builds project, please see the Contribute page on our website. In this report:
  1. Reproducible Builds Summit 2025
  2. Reproducible Builds an official goal for SUSE Enterprise Linux
  3. Reproducible Builds at FOSSY 2025
  4. New OSS Rebuild project from Google
  5. New extension of Python setuptools to support reproducible builds
  6. diffoscope
  7. New library to patch system functions for reproducibility
  8. Independently Reproducible Git Bundles
  9. Website updates
  10. Distribution work
  11. Reproducibility testing framework
  12. Upstream patches

Reproducible Builds Summit 2025 We are extremely pleased to announce the upcoming Reproducible Builds Summit, set to take place from October 28th 30th 2025 in Vienna, Austria! We are thrilled to host the eighth edition of this exciting event, following the success of previous summits in various iconic locations around the world, including Venice, Marrakesh, Paris, Berlin, Hamburg and Athens. Our summits are a unique gathering that brings together attendees from diverse projects, united by a shared vision of advancing the Reproducible Builds effort. During this enriching event, participants will have the opportunity to engage in discussions, establish connections and exchange ideas to drive progress in this vital field. Our aim is to create an inclusive space that fosters collaboration, innovation and problem-solving. If you re interesting in joining us this year, please make sure to read the event page which has more details about the event and location. Registration is open until 20th September 2025, and we are very much looking forward to seeing many readers of these reports there!

Reproducible Builds an official goal for SUSE Enterprise Linux On our mailing list this month, Bernhard M. Wiedemann revealed the big news that reproducibility is now an official goal for SUSE Linux Enterprise Server (SLES) 16:
[Everything] changed earlier this year when reproducible-builds for SLES-16 became an official goal for the product. More people are talking about digital sovereignty and supply-chain security now. [ ] Today, only 9 of 3319 (source) packages have significant problems left (plus 7 with pending fixes), so 99.5% of packages have reproducible builds.

Reproducible Builds at FOSSY 2025 On Saturday 2nd August, Vagrant Cascadian and Chris Lamb presented at this year s FOSSY 2025. Their talk, titled Never Mind the Checkboxes, Here s Reproducible Builds!, was introduced as follows:
There are numerous policy compliance and regulatory processes being developed that target software development but do they solve actual problems? Does it improve the quality of software? Do Software Bill of Materials (SBOMs) actually give you the information necessary to verify how a given software artifact was built? What is the goal of all these compliance checklists anyways or more importantly, what should the goals be? If a software object is signed, who should be trusted to sign it, and can they be trusted forever?
Hosted by the Software Freedom Conservancy and taking place in Portland, Oregon, USA, FOSSY aims to be a community-focused event: Whether you are a long time contributing member of a free software project, a recent graduate of a coding bootcamp or university, or just have an interest in the possibilities that free and open source software bring, FOSSY will have something for you . More information on the event is available on the FOSSY 2025 website, including the full programme schedule. Vagrant and Chris also staffed a table, where they will be available to answer any questions about Reproducible Builds and discuss collaborations with other projects.

New OSS Rebuild project from Google The Google Open Source Security Team (GOSST) published an article this month announcing OSS Rebuild, a new project to strengthen trust in open source package ecosystems by reproducing upstream artifacts. As the post itself documents, the new project comprises four facets:
  • Automation to derive declarative build definitions for existing PyPI (Python), npm (JS/TS), and Crates.io (Rust) packages.
  • SLSA Provenance for thousands of packages across our supported ecosystems, meeting SLSA Build Level 3 requirements with no publisher intervention.
  • Build observability and verification tools that security teams can integrate into their existing vulnerability management workflows.
  • Infrastructure definitions to allow organizations to easily run their own instances of OSS Rebuild to rebuild, generate, sign, and distribute provenance.
One difference with most projects that aim for bit-for-bit reproducibility, OSS Rebuild aims for a kind of semantic reproducibility:
Through automation and heuristics, we determine a prospective build definition for a target package and rebuild it. We semantically compare the result with the existing upstream artifact, normalizing each one to remove instabilities that cause bit-for-bit comparisons to fail (e.g. archive compression).
The extensive post includes examples about how to access OSS Rebuild attestations using the Go-based command-line interface.

New extension of Python setuptools to support reproducible builds Wim Jeantine-Glenn has written a PEP 517 Build backend in order to enable reproducible builds when building Python projects that use setuptools. Called setuptools-reproducible, the project s README file contains the following:
Setuptools can create reproducible wheel archives (.whl) by setting SOURCE_DATE_EPOCH at build time, but setting the env var is insufficient for creating reproducible sdists (.tar.gz). setuptools-reproducible [therefore] wraps the hooks build_sdist build_wheel with some modifications to make reproducible builds by default.

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 versions 301, 302 and 303 to Debian:
  • Improvements:
    • Use Difference.from_operation in an attempt to pipeline the output of the extract-vmlinux script, potentially avoiding it all in memory. [ ]
    • Memoize a number of calls to --version, saving a very large number of external subprocess calls.
  • Bug fixes:
    • Don t check for PyPDF version 3 specifically, check for versions greater than 3. [ ]
    • Ensure that Java class files are named .class on the filesystem before passing them to javap(1). [ ]
    • Mask stderr from extract-vmlinux script. [ ][ ]
    • Avoid spurious differences in h5dump output caused by exposure of absolute internal extraction paths. (#1108690)
  • Misc:
    • Use our_check_output in the ODT comparator. [ ]
    • Update copyright years. [ ]
In addition: Lastly, Chris Lamb added a tmpfs to try.diffoscope.org so that diffoscope has a non-trivial temporary area to unpack archives, etc. [ ] Elsewhere in our tooling, however, 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, reprotest version 0.7.30 was uploaded to Debian unstable by Holger Levsen, chiefly including a change by Rebecca N. Palmer to not call sudo with the -h flag in order to fix Debian bug #1108550. [ ]

New library to patch system functions for reproducibility Nicolas Graves has written and published libfate, a simple collection of tiny libraries to patch system functions deterministically using LD_PRELOAD. According to the project s README:
libfate provides deterministic replacements for common non-deterministic system functions that can break reproducible builds. Instead of relying on complex build systems or apps or extensive patching, libfate uses the LD_PRELOAD trick to intercept system calls and return fixed, predictable values.
Describing why he wrote it, Nicolas writes:
I originally used the OpenSUSE dettrace approach to make Emacs reproducible in Guix. But when Guix switch to GCC@14, dettrace stopped working as expected. dettrace is a complex piece of software, my need was much less heavy: I don t need to systematically patch all sources of nondetermism, just the ones that make a process/binary unreproducible in a container/chroot.

Independently Reproducible Git Bundles Simon Josefsson has published another interesting article this month. Titled Independently Reproducible Git Bundles, the blog post describes the advantages of why you might a reproducible bundle, and the pitfalls that can arise when trying to create them:
One desirable property is that someone else should be able to reproduce the same git bundle, and not only that a single individual is able to reproduce things on one machine. It surprised me to see that when I ran the same set of commands on a different machine (started from a fresh git clone), I got a different checksum. The different checksums occurred even when nothing had been committed on the server side between the two runs.

Website updates Once again, there were a number of improvements made to our website this month including:

Distribution work In Debian this month:
Debian contributors have made significant progress toward ensuring package builds produce byte-for-byte reproducible results. You can check the status for packages installed on your system using the new package debian-repro-status, or visit reproduce.debian.net for Debian s overall statistics for trixie and later. You can contribute to these efforts by joining #debian-reproducible on IRC to discuss fixes, or verify the statistics by installing the new rebuilderd package and setting up your own instance.

The IzzyOnDroid Android APK repository made further progress in July, crossing the 50% reproducibility threshold congratulations. Furthermore, a new release of the Neo Store was released, which exposes the reproducible status directly next to the version of each app.
In GNU Guix, a series of patches intended to fix the reproducibility for the Mono programming language was merged, fixing reproducibility in Mono versions 1.9 [ ], 2.4 [ ] and 2.6 [ ].
Lastly, in addition to the news that openSUSE Enterprise Linux now [has an official goal of reproducibility]((https://lists.reproducible-builds.org/pipermail/rb-general/2025-July/003846.html), Bernhard M. Wiedemann posted another monthly update for their work there.

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 July, however, a number of changes were made by Holger Levsen, including:
  • Switch the URL for the Tails package set. [ ]
  • Make the dsa-check-packages output more useful. [ ]
  • Setup the ppc64el architecture again, has it has returned this time with a 2.7 GiB database instead of 72 GiB. [ ]
In addition, Jochen Sprickerhof improved the reproducibility statistics generation:
  • Enable caching of statistics. [ ][ ][ ]
  • Add some common non-reproducible patterns. [ ]
  • Change output to directory. [ ]
  • Add a page sorted by diffoscope size. [ ][ ]
  • Switch to Python s argparse module and separate output(). [ ]
Holger also submitted a number of Debian bugs against rebuilderd and rebuilderd-worker:
  • Config files and scripts for a simple one machine setup. [ ][ ]
  • Create a rebuilderd user. [ ]
  • Create rebuilderd-worker user with sbuild. [ ]
Lastly, Mattia Rizzolo added a scheduled job to renew some SSL certificates [ ] and Vagrant Cascadian performed some node maintenance [ ][ ].

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: There were a number of other patches from openSUSE developers:

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:

David Bremner: Using git-annex for email and notmuch metadata

Introducing git-remote-notmuch Based on an idea and ruby implementation by Felipe Contreras, I have been developing a git remote helper for notmuch. I will soon post an updated version of the patchset to the notmuch mailing list (I wanted to refer to this post in my email). In this blog post I'll outline my experiments with using that tool, along with git-annex to store (and sync) a moderate sized email store along with its notmuch metadata.

WARNING The rest of this post describes some relatively complex operations using (at best) alpha level software (namely git-remote-notmuch). git-annex is good at not losing your files, but git-remote-notmuch can (and did several times during debugging) wipe out your notmuch database. If you have a backup (e.g. made with notmuch-dump), this is much less annoying, and in particular you can decide to walk away from this whole experiment and restore your database.

Why git-annex? I currently have about 31GiB of email, spread across more than 830,000 files. I want to maintain the ability to search and read my email offline, so I need to maintain a copy on several workstations and at least one server (which is backed up explicitly). I am somewhat commited to maintaining synchronization of tags to git since that is how the notmuch bug tracker works. Commiting the email files to git seems a bit wasteful: by design notmuch does not modify email files, and even with compression, the extra copy adds a fair amount of overhead (in my case, 17G of git objects, about 57% overhead). It is also notoriously difficult to completely delete files from a git repository. git-annex offers potential mitigation for these two issues, at the cost of a somewhat more complex mental model. The main idea is that instead of committing every version of a file to the git repository, git-annex tracks the filename and metadata, with the file content being stored in a key-value store outside git. Conceptually this is similar to git-lfs. From our current point, the important point is that instead of a second (compressed) copy of the file, we store one copy, along with a symlink and a couple of directory entries.

What to annex For sufficiently small files, the overhead of a symlink and couple of directory entries is greater than the cost of a compressed second copy. When this happens depends on several variables, and will probably depend on the file content in a particular collection of email. I did a few trials of different settings for annex.largefiles to come to a threshold of largerthan=32k 1. For the curious, my experimental results are below. One potentially surprising aspect is that annexing even a small fraction of the (largest) files yields a big drop in storage overhead.
Threshold fraction annexed overhead
0 100% 30%
8k 29% 13%
16k 12% 9.4%
32k 7% 8.9%
48k 6% 8.9%
100k 3% 9.1%
256k 2% 11%
(git) 0 % 57%
In the end I chose to err on the side of annexing more files (for the flexibility of deletion) rather than potentially faster operations with fewer annexed files at the same level of overhead. Summarizing the configuration settings for git-annex (some of these are actually defaults, but not in my environment).
$ git config annex.largefiles largerthan=32k
$ git config annex.dotfiles true
$ git config annex.synccontent true

Delivering mail To get new mail, I do something like
# compute a date based folder under $HOME/Maildir
$ dest = $(folder)
# deliver mail to $ dest  (somehow).
$ notmuch new
$ git -C $HOME/Maildir add $ folder 
$ git -C $HOME/Maildir diff-index --quiet HEAD $ folder    git -C $HOME/Maildir commit -m 'mail delivery'
The call to diff-index is just an optimization for the case when nothing was delivered. The default configuration of git-annex will automagically annex any files larger than my threshold. At this point the git-annex repo knows nothing about tags. There is some git configuration that can speed up the "git add" above, namely
$ git config core.untrackedCache true
$ git config core.fsmonitor true
See git-status(1) under "UNTRACKED FILES AND PERFORMANCE" Defining notmuch as a git remote Assuming git-remote-notmuch is somewhere in your path, you can define a remote to connect to the default notmuch database.
$ git remote add database notmuch::
$ git fetch database
$ git merge --allow-unrelated database
The --allow-unrelated should be needed only the first time. In my case the many small files used to represent the tags (one per message), use a noticeable amount of disk space (in my case about the same amount of space as the xapian database). Once you start merging from the database to the git repo, you will likely have some conflicts, and most conflict resolution tools leave junk lying around. I added the following .gitignore file to the top level of the repo
*.orig
*~
This prevents our cavalier use of git add from adding these files to our git history (and prevents pushing random junk to the notmuch database. To push the tags from git to notmuch, you can run
$ git push database master
You might need to run notmuch new first, so that the database knows about all of the messages (currently git-remote-notmuch can't index files, only update metadata). git annex sync should work with the new remote, but pushing back will be very slow 2. I disable automatic pushing as follows
$ git config remote.database.annex-push false
Unsticking the database remote If you are debugging git-remote-notmuch, or just unlucky, you may end up in a sitation where git thinks the database is ahead of your git remote. You can delete the database remote (and associated stuff) and re-create it. Although I cannot promise this will never cause problems (because, computers), it will not modify your local copy of the tags in the git repo, nor modify your notmuch database.
$ git remote rm database
$ git update-rf -d notmuch/master
$ rm -r .git/notmuch
Fine tuning notmuch config
  • In order to avoid dealing with file renames, I have
      notmuch config maildir.synchronize_flags false
    
  • I have added the following to new.ignore:
       .git;_notmuch_metadata;.gitignore
    

  1. I also had to set annex.dotfiles to true, as many of my maildirs follow the qmail style convention of starting with a .
  2. I'm not totally clear on why it so slow, but certainly git-annex tries to push several more branches, and these are ignored by git-remote-annex.

Colin Watson: Free software activity in July 2025

About 90% of my Debian contributions this month were sponsored by Freexian. You can also support my work directly via Liberapay or GitHub Sponsors. DebConf I attended DebConf for the first time in 11 years (my last one was DebConf 14 in Portland). It was great! For once I had a conference where I had a fairly light load of things I absolutely had to do, so I was able to spend time catching up with old friends, making some new friends, and doing some volunteering - a bit of Front Desk, and quite a lot of video team work where I got to play with sound desks and such. Apparently one of the BoFs ( birds of a feather , i.e. relatively open discussion sessions) where I was talkmeister managed to break the automatic video cutting system by starting and ending precisely on time, to the second, which I m told has never happened before. I ll take that. I gave a talk about Debusine, along with helping Enrico run a Debusine BoF. We still need to process some of the feedback from this, but are generally pretty thrilled about the reception. My personal highlight was getting a shout-out in a talk from CERN (in the slide starting at 32:55). Other highlights for me included a Python team BoF, Ian s tag2upload talk and some very useful follow-up discussions, a session on archive-wide testing, a somewhat brain-melting whiteboard session about the multiarch interpreter problem , several useful discussions about salsa.debian.org, Matthew s talk on how Wikimedia automates their Debian package builds, and many others. I hope I can start attending regularly again! OpenSSH Towards the end of a release cycle, people tend to do more upgrade testing, and this sometimes results in interesting problems. Manfred Stock reported No new SSH connections possible during large part of upgrade to Debian Trixie , and after a little testing in a container I confirmed that this was a reproducible problem that would have affected many people upgrading from Debian 12 (bookworm), with potentially severe consequences for people upgrading remote systems. In fact, there were two independent problems that each led to much the same symptom: The net result is that if you apply updates to bookworm (including stable-updates / bookworm-updates, which is enabled by default) before starting the upgrade to trixie, everything should be fine. Many thanks to Manfred for reporting this with just enough time to spare that we were able to fix it before Debian 13 is released in a few days! debmirror I did my twice-yearly refresh of debmirror s mirror_size documentation, and applied a patch from Christoph Goehre to improve mirroring of installer files. madison-lite I proposed renaming this project along with the rmadison tool in devscripts, although I m not yet sure what a good replacement name would be. Python team I upgraded python-expandvars, python-typing-extensions (in experimental), and webtest to new upstream versions. I backported fixes for some security vulnerabilities to unstable: I fixed or helped to fix a number of release-critical bugs: I fixed some other bugs, mostly Severity: important: I reinstated python3-mastodon s build-dependency on and recommendation of python3-blurhash, now that the latter has been fixed to use the correct upstream source.

5 August 2025

Matthew Garrett: Cordoomceps - replacing an Amiga's brain with Doom

There's a lovely device called a pistorm, an adapter board that glues a Raspberry Pi GPIO bus to a Motorola 68000 bus. The intended use case is that you plug it into a 68000 device and then run an emulator that reads instructions from hardware (ROM or RAM) and emulates them. You're still limited by the ~7MHz bus that the hardware is running at, but you can run the instructions as fast as you want.

These days you're supposed to run a custom built OS on the Pi that just does 68000 emulation, but initially it ran Linux on the Pi and a userland 68000 emulator process. And, well, that got me thinking. The emulator takes 68000 instructions, emulates them, and then talks to the hardware to implement the effects of those instructions. What if we, well, just don't? What if we just run all of our code in Linux on an ARM core and then talk to the Amiga hardware?

We're going to ignore x86 here, because it's weird - but most hardware that wants software to be able to communicate with it maps itself into the same address space that RAM is in. You can write to a byte of RAM, or you can write to a piece of hardware that's effectively pretending to be RAM[1]. The Amiga wasn't unusual in this respect in the 80s, and to talk to the graphics hardware you speak to a special address range that gets sent to that hardware instead of to RAM. The CPU knows nothing about this. It just indicates it wants to write to an address, and then sends the data.

So, if we are the CPU, we can just indicate that we want to write to an address, and provide the data. And those addresses can correspond to the hardware. So, we can write to the RAM that belongs to the Amiga, and we can write to the hardware that isn't RAM but pretends to be. And that means we can run whatever we want on the Pi and then access Amiga hardware.

And, obviously, the thing we want to run is Doom, because that's what everyone runs in fucked up hardware situations.

Doom was Amiga kryptonite. Its entire graphical model was based on memory directly representing the contents of your display, and being able to modify that by just moving pixels around. This worked because at the time VGA displays supported having a memory layout where each pixel on your screen was represented by a byte in memory containing an 8 bit value that corresponded to a lookup table containing the RGB value for that pixel.

The Amiga was, well, not good at this. Back in the 80s, when the Amiga hardware was developed, memory was expensive. Dedicating that much RAM to the video hardware was unthinkable - the Amiga 1000 initially shipped with only 256K of RAM, and you could fill all of that with a sufficiently colourful picture. So instead of having the idea of each pixel being associated with a specific area of memory, the Amiga used bitmaps. A bitmap is an area of memory that represents the screen, but only represents one bit of the colour depth. If you have a black and white display, you only need one bitmap. If you want to display four colours, you need two. More colours, more bitmaps. And each bitmap is stored in an independent area of RAM. You never use more memory than you need to display the number of colours you want to.

But that means that each bitplane contains packed information - every byte of data in a bitplane contains the bit value for 8 different pixels, because each bitplane contains one bit of information per pixel. To update one pixel on screen, you need to read from every bitmap, update one bit, and write it back, and that's a lot of additional memory accesses. Doom, but on the Amiga, was slow not just because the CPU was slow, but because there was a lot of manipulation of data to turn it into the format the Amiga wanted and then push that over a fairly slow memory bus to have it displayed.

The CDTV was an aesthetically pleasing piece of hardware that absolutely sucked. It was an Amiga 500 in a hi-fi box with a caddy-loading CD drive, and it ran software that was just awful. There's no path to remediation here. No compelling apps were ever released. It's a terrible device. I love it. I bought one in 1996 because a local computer store had one and I pointed out that the company selling it had gone bankrupt some years earlier and literally nobody in my farming town was ever going to have any interest in buying a CD player that made a whirring noise when you turned it on because it had a fan and eventually they just sold it to me for not much money, and ever since then I wanted to have a CD player that ran Linux and well spoiler 30 years later I'm nearly there. That CDTV is going to be our test subject. We're going to try to get Doom running on it without executing any 68000 instructions.

We're facing two main problems here. The first is that all Amigas have a firmware ROM called Kickstart that runs at powerup. No matter how little you care about using any OS functionality, you can't start running your code until Kickstart has run. This means even documentation describing bare metal Amiga programming assumes that the hardware is already in the state that Kickstart left it in. This will become important later. The second is that we're going to need to actually write the code to use the Amiga hardware.

First, let's talk about Amiga graphics. We've already covered bitmaps, but for anyone used to modern hardware that's not the weirdest thing about what we're dealing with here. The CDTV's chipset supports a maximum of 64 colours in a mode called "Extra Half-Brite", or EHB, where you have 32 colours arbitrarily chosen from a palette and then 32 more colours that are identical but with half the intensity. For 64 colours we need 6 bitplanes, each of which can be located arbitrarily in the region of RAM accessible to the chipset ("chip RAM", distinguished from "fast ram" that's only accessible to the CPU). We tell the chipset where our bitplanes are and it displays them. Or, well, it does for a frame - after that the registers that pointed at our bitplanes no longer do, because when the hardware was DMAing through the bitplanes to display them it was incrementing those registers to point at the next address to DMA from. Which means that every frame we need to set those registers back.

Making sure you have code that's called every frame just to make your graphics work sounds intensely irritating, so Commodore gave us a way to avoid doing that. The chipset includes a coprocessor called "copper". Copper doesn't have a large set of features - in fact, it only has three. The first is that it can program chipset registers. The second is that it can wait for a specific point in screen scanout. The third (which we don't care about here) is that it can optionally skip an instruction if a certain point in screen scanout has already been reached. We can write a program (a "copper list") for the copper that tells it to program the chipset registers with the locations of our bitplanes and then wait until the end of the frame, at which point it will repeat the process. Now our bitplane pointers are always valid at the start of a frame.

Ok! We know how to display stuff. Now we just need to deal with not having 256 colours, and the whole "Doom expects pixels" thing. For the first of these, I stole code from ADoom, the only Amiga doom port I could easily find source for. This looks at the 256 colour palette loaded by Doom and calculates the closest approximation it can within the constraints of EHB. ADoom also includes a bunch of CPU-specific assembly optimisation for converting the "chunky" Doom graphic buffer into the "planar" Amiga bitplanes, none of which I used because (a) it's all for 68000 series CPUs and we're running on ARM, and (b) I have a quad core CPU running at 1.4GHz and I'm going to be pushing all the graphics over a 7.14MHz bus, the graphics mode conversion is not going to be the bottleneck here. Instead I just wrote a series of nested for loops that iterate through each pixel and update each bitplane and called it a day. The set of bitplanes I'm operating on here is allocated on the Linux side so I can read and write to them without being restricted by the speed of the Amiga bus (remember, each byte in each bitplane is going to be updated 8 times per frame, because it holds bits associated with 8 pixels), and then copied over to the Amiga's RAM once the frame is complete.

And, kind of astonishingly, this works! Once I'd figured out where I was going wrong with RGB ordering and which order the bitplanes go in, I had a recognisable copy of Doom running. Unfortunately there were weird graphical glitches - sometimes blocks would be entirely the wrong colour. It took me a while to figure out what was going on and then I felt stupid. Recording the screen and watching in slow motion revealed that the glitches often showed parts of two frames displaying at once. The Amiga hardware is taking responsibility for scanning out the frames, and the code on the Linux side isn't synchronised with it at all. That means I could update the bitplanes while the Amiga was scanning them out, resulting in a mashup of planes from two different Doom frames being used as one Amiga frame. One approach to avoid this would be to tie the Doom event loop to the Amiga, blocking my writes until the end of scanout. The other is to use double-buffering - have two sets of bitplanes, one being displayed and the other being written to. This consumes more RAM but since I'm not using the Amiga RAM for anything else that's not a problem. With this approach I have two copper lists, one for each set of bitplanes, and switch between them on each frame. This improved things a lot but not entirely, and there's still glitches when the palette is being updated (because there's only one set of colour registers), something Doom does rather a lot, so I'm going to need to implement proper synchronisation.

Except. This was only working if I ran a 68K emulator first in order to run Kickstart. If I tried accessing the hardware without doing that, things were in a weird state. I could update the colour registers, but accessing RAM didn't work - I could read stuff out, but anything I wrote vanished. Some more digging cleared that up. When you turn on a CPU it needs to start executing code from somewhere. On modern x86 systems it starts from a hardcoded address of 0xFFFFFFF0, which was traditionally a long way any RAM. The 68000 family instead reads its start address from address 0x00000004, which overlaps with where the Amiga chip RAM is. We can't write anything to RAM until we're executing code, and we can't execute code until we tell the CPU where the code is, which seems like a problem. This is solved on the Amiga by powering up in a state where the Kickstart ROM is "overlayed" onto address 0. The CPU reads the start address from the ROM, which causes it to jump into the ROM and start executing code there. Early on, the code tells the hardware to stop overlaying the ROM onto the low addresses, and now the RAM is available. This is poorly documented because it's not something you need to care if you execute Kickstart which every actual Amiga does and I'm only in this position because I've made poor life choices, but ok that explained things. To turn off the overlay you write to a register in one of the Complex Interface Adaptor (CIA) chips, and things start working like you'd expect.

Except, they don't. Writing to that register did nothing for me. I assumed that there was some other register I needed to write to first, and went to the extent of tracing every register access that occurred when running the emulator and replaying those in my code. Nope, still broken. What I finally discovered is that you need to pulse the reset line on the board before some of the hardware starts working - powering it up doesn't put you in a well defined state, but resetting it does.

So, I now have a slightly graphically glitchy copy of Doom running without any sound, displaying on an Amiga whose brain has been replaced with a parasitic Linux. Further updates will likely make things even worse. Code is, of course, available.

[1] This is why we had trouble with late era 32 bit systems and 4GB of RAM - a bunch of your hardware wanted to be in the same address space and so you couldn't put RAM there so you ended up with less than 4GB of RAM

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4 August 2025

Freexian Collaborators: Secure boot signing with Debusine (by Colin Watson)

Debusine aims to be an integrated solution to build, distribute and maintain a Debian-based distribution. At Debconf 25, we talked about using it to pre-test uploads to Debian unstable, and also touched on how Freexian is using it to help maintain the Debian LTS and ELTS projects. When Debian 10 (buster) moved to ELTS status in 2024, this came with a new difficulty that hadn t existed for earlier releases. Debian 10 added UEFI Secure Boot support, meaning that there are now signed variants of the boot loader and Linux kernel packages. Debian has a system where certain packages are configured as needing to be signed, and those packages include a template for a source package along with the unsigned objects themselves. The signing service generates detached signatures for all those objects, and then uses the template to build a source package that it uploads back to the archive for building in the usual way. Once buster moved to ELTS, it could no longer rely on Debian s signing service for all this. Freexian operates parallel infrastructure for the archive, and now needed to operate a parallel signing service as well. By early 2024 we were already planning to move ELTS infrastructure towards Debusine, and so it made sense to build a signing service there as well. Separately, we were able to obtain a Microsoft signature for Freexian s shim build, allowing us to chain this into the trust path for most deployed x86 machines. Freexian can help other organizations running Debian derivatives through the same process, and can provide secure signing infrastructure to the standards required for UEFI Secure Boot.

Prior art We considered both code-signing (Debian s current implementation) and lp-signing (Ubuntu s current implementation) as prior art. Neither was quite suitable for various reasons.
  • code-signing relies on polling a configured URL for each archive to fetch a GPG-signed list of signing requests, which would have been awkward for us to set up, and it assumes that unsigned packages are sufficiently trusted for it to be able to run dpkg -x and dpkg-source -b on them outside any containment. dpkg -x has had the occasional security vulnerability, so this seemed unwise for a service that might need to deal with signing packages for multiple customers.
  • lp-signing is a microservice accepting authenticated requests, and is careful to avoid needing to manipulate packages itself. However, this relies on a different and incompatible mechanism for indicating that packages should be signed, which wasn t something we wanted to introduce in ELTS.

Workers Debusine already had an established system of external workers that run tasks under various kinds of containment. This seems like a good fit: after all, what s a request to sign a package but a particular kind of task? But there are some problems here: workers can run essentially arbitrary code (such as build scripts in source packages), and even though that s under containment, we don t want to give such machines access to highly-sensitive data such as private keys. Fortunately, we d already introduced the idea of different kinds of workers a few months beforehand, in order to be able to run privileged server tasks that have direct access to the Debusine database. We built on that and added signing workers , which are much like external workers except that they only run signing tasks, no other types of tasks run on them, and they have access to a private database with information about the keys managed by their Debusine instance. (Django s support for multiple databases made this quite easy to arrange: we were able to keep everything in the same codebase.)

Key management It s obviously bad practice to store private key material in the clear, but at the same time the signing workers are essentially oracles that will return signatures on request while ensuring that the rest of Debusine has no access to private key material, so they need to be able to get hold of it themselves. Hardware security modules (HSMs) are designed for this kind of thing, but they can be inconvenient to manage when large numbers of keys are involved. Some keys are more valuable than others. If the signing key used for an experimental archive leaks, the harm is unlikely to be particularly serious; but if the ELTS signing key leaks, many customers will be affected. To match this, we implemented two key protection arrangements for the time being: one suitable for low-value keys encrypts the key in software with a configured key and stores the public key and ciphertext in the database, while one suitable for high-value keys stores keys as PKCS #11 URIs that can be set up manually by an instance administrator. We packaged some YubiHSM tools to make this easier for our sysadmins. The signing worker calls back to the Debusine server to check whether a given work request is authorized to use a given signing key. All operations related to private keys also produce an audit log entry in the private signing database, so we can track down any misuse.

Tasks Getting Debusine to do anything new usually requires figuring out how to model the operation as a task. In this case, that was complicated by wanting to run as little code as possible on the signing workers: in particular, we didn t want to do all the complicated package manipulations there. The approach we landed on was a chain of three tasks:
  • ExtractForSigning runs on a normal external worker. It takes the result of a package build and picks out the individual files from it that need to be signed, storing them as separate artifacts.
  • Sign runs on a signing worker, and (of course) makes the actual signatures, storing them as artifacts.
  • AssembleSignedSource runs on a normal external worker. It takes the signed artifacts and produces a source package containing them, based on the template found in the unsigned binary package.

Workflows Of course, we don t want people to have to create all those tasks directly and figure out how to connect everything together for themselves, and that s what workflows are good at. The make_signed_source workflow does all the heavy lifting of creating the right tasks with the right input data and making them depend on each other in the right ways, including fanning out multiple copies of all this if there are multiple architectures or multiple template packages involved. Since you probably don t want to stop at just having the signed source packages, it also kicks off builds to produce signed binary packages. Even this is too low-level for most people to use directly, so we wrapped it all up in our debian_pipeline workflow, which just needs to be given a few options to enable signing support (and those options can be locked down by workspace owners).

What s next? In most cases this work has been enough to allow ELTS to carry on issuing kernel security updates without too much disruption, which was the main goal; but there are other uses for a signing system. We included OpenPGP support from early on, which allows Debusine to sign its own builds, and we ll soon be extending that to sign APT repositories hosted by Debusine. The current key protection arrangements could use some work. Supporting automatically-generated software-encrypted keys and manually-generated keys in an HSM is fine as far as it goes, but it would be good to be able to have the best of both worlds by being able to automatically generate keys protected by an HSM. This needs some care, as HSMs often have quite small limits on the number of objects they can store at any one time, and the usual workaround is to export keys from the HSM under wrap (encrypted by a key known only to the HSM) so that they can be imported only when needed. We have a general idea of how to do this, but doing it efficiently will need care. We d be very interested in hearing from organizations that need this sort of thing, especially for Debian derivatives. Debusine provides lots of other features that can help you. Please get in touch with us at sales@freexian.com if any of this sounds useful to you.

3 August 2025

Aigars Mahinovs: Debconf 25 photos

Debconf 25 photos Debconf 25 came to the end in Brest, France this year a couple weeks ago. This has been a very different and unusually interesting Debconf. For me it was for two, related reasons: for one the conference was close enough in Western Europe that I could simply drive there with a car (which reminds me that I should make a blog post about the BMW i5, before I am done with it at the end of this year) and for the other - the conference is close enough to Western Europe that many other Debian developers could join this year who have not been seen at the event for many years. Being able to arrive early, decompress and spend extra time looking around the place made the event itself even more enjoyable than usual. The French cuisine, especially in its Breton expression, has been a very welcome treat. Even if there were some rough patches with the food selection, amount, or waiting, it was still a great experience. I specifically want to say a big thank you to the organisers for everything, but very explicitly for planning all the talk/BOF rooms in the same building and almost on the same floor. It saved me a lot of footwork, but also for other participants the short walks between the talks made it possible to always have a few minutes to talk to people or grab a croissant before running to the next talk. IMHO we should come back to a tradition of organising Debconf in Europe every 2-3 years. This maximises one of the main goals of Debconf - bringing as many Debian Developers as possible together in one physical location. This works best when the location is actually close to large concentrations of existing developers. In other years, the other goal of Debconf can then take priority - recruiting new developers in new locations. However, these goals could both be achieved at the same time - there are plenty of locations in Europe and even in Western Europe that still have good potential for attracting new developers. Especially if we focus on organising the event on the campuses of some larger technically-oriented universities. This year was also very productive for me a lot of conversations with various people about all kinds of topics, especially technical packaging questions. It has been a long time since the very basic foundations of Debian packaging work have been so fundamentally refactored and modernized as in the past year. Tag2upload has become a catalyst for git-based packaging and for automated workflows via Salsa, and all of that feeds back into focusing on a few best-supported packaging workflows. There is still a bit of a documentation gap of a new contributor getting to these modern packaging workflows from the point where the New Maintainers Guide stops. In any case, next year Debconf will be happening in Santa Fe, Argentina. And the year after that it is all still open and in a close competition between Japan, Spain, Portugal, Brazil and .. El Salvador? Personally, I would love to travel to Japan (again), but Spain or Portugal would also be great locations to meet more European developers again. As for Santa Fe ... it is quite likely that I will not be able to make it there next year, for (planned) health reasons. I guess I should also write a new blog post about what it means to be a Debconf Photographer, so that someone else could do this as well, and also reduce the "bus factor" along the way. But before that - here is the main group photo from this year: DebConf 25 Group photo You can also see it on: You can also enjoy the rest of the photos: Additionally, check out photos from other people on GIT LFS and consider adding your own photos there as well. Other places I have updated with up-to-date information are these wiki pages: If you took part in the playing cards event, then check your photo in this folder and link to your favourite from your line in the playing card wiki

Ben Hutchings: FOSS activity in July 2025

In July I attended DebCamp and DebConf in Brest, France. I very much enjoyed the opportunity to reconnect with other Debian contributors in person. I had a number of interesting and fruitful conversations there, besides the formally organised BoFs and talks. I also gave my own talk on What s new in the Linux kernel (and what s missing in Debian). Here s the usual categorisation of activity:

2 August 2025

Raju Devidas: Use phone/tablets/other laptops as external monitor with your laptop

This method is for wayland based systems. There are better ways to do this on GNOME or KDE desktops, but the method we are going to use is independent of DE/WM that you are using. I am doing this on sway window manager, but you can try this on any other Wayland based WM or DE. I have not tried this on Xorg based systems, there are several other guides for Xorg based systems online. When we connect a physical monitor to our laptops, it creates a second display output in our display settings that we can then re-arrange in layout, set resolution, set scale etc. Since we are not connecting via a physical interface like HDMI, DP, VGA etc. We need to create a virtual display within our system and set the display properties manually.
Get a list of current display outputs. You can also just check it in display settings of your DE/WM with wdisplays
rajudev@sanganak ~> swaymsg -t get_outputs
Output LVDS-1 &aposSeiko Epson Corporation 0x3047 Unknown&apos (focused)
  Current mode: 1366x768 @ 60.002 Hz
  Power: on
  Position: 0,0
  Scale factor: 1.000000
  Scale filter: nearest
  Subpixel hinting: rgb
  Transform: normal
  Workspace: 2
  Max render time: off
  Adaptive sync: disabled
  Allow tearing: no
  Available modes:
    1366x768 @ 60.002 Hz
altSingle physical display of the laptop
Currently we are seeing only one display output. Our goal is to create a second virtual display that we will then share on the tablet/phone. To do this there are various tools available. We are using sway-vdctl . It is currently not available within Debian packages, so we need to install it manually.
$ git clone https://github.com/odincat/sway-vdctl.git
$ cd sway-vdctl
$ cargo build --release
This will generate the binary with the name main under target/release . We can then copy this binary to our bin folder.
$ sudo cp target/release/main /usr/local/bin/vdctl
Now we have the vdctl command available.
$ vdctl --help
Usage: vdctl [OPTIONS] <ACTION> [VALUE]
Arguments:
  <ACTION>
          Possible values:
          - create:      Create new output based on a preset
          - kill:        Terminate / unplug an active preset
          - list:        List out active presets
          - next-number: Manually set the next output number, in case something breaks
          - sync-number: Sync the next output number using &aposswaymsg -t get_outputs&apos
  [VALUE]
          Preset name to apply, alternatively a value
          
          [default: ]
Options:
      --novnc
          do not launch a vnc server, just create the output
  -h, --help
          Print help (see a summary with &apos-h&apos)
Before creating the virtual display, we need to set it&aposs properties at .config/vdctl/config.json . I am using Xiaomi Pad 6 tablet as my external display. You can adjust the properties according to the device you want to use as a second display. $ (text-editor) .config/vdctl/config.json
 
    "host": "0.0.0.0",
    "presets": [
         
            "name": "pad6",
            "scale_factor": 2,
            "port": 9901,
            "resolution":  
                "width": 2800,
                "height": 1800
             
       
    ]
 
In the JSON, you can set the display resolution according to your external device and other configurations. If you want to configure multiple displays, you can add another entry into the presets in the json file. You can refer to example json file into the git repository. Now we need to actually create the virtual monitor.
$ vdctl create pad6
Created output, presumably &aposHEADLESS-1&apos
Set resolution of &aposHEADLESS-1&apos to 2800x1800
Set scale factor of &aposHEADLESS-1&apos to 2
Preset &apospad6&apos (&aposHEADLESS-1&apos: 2800x1800) is now active on port 9901
Now if you will check the display outputs in your display settings or from command line, you will see two different displays.
$ swaymsg -t get_outputs
Output LVDS-1 &aposSeiko Epson Corporation 0x3047 Unknown&apos
  Current mode: 1366x768 @ 60.002 Hz
  Power: on
  Position: 0,0
  Scale factor: 1.000000
  Scale filter: nearest
  Subpixel hinting: rgb
  Transform: normal
  Workspace: 2
  Max render time: off
  Adaptive sync: disabled
  Allow tearing: no
  Available modes:
    1366x768 @ 60.002 Hz
Output HEADLESS-1 &aposUnknown Unknown Unknown&apos (focused)
  Current mode: 2800x1800 @ 0.000 Hz
  Power: on
  Position: 1366,0
  Scale factor: 2.000000
  Scale filter: nearest
  Subpixel hinting: unknown
  Transform: normal
  Workspace: 3
  Max render time: off
  Adaptive sync: disabled
  Allow tearing: no
Also in the display settings.
altDisplay settings on Wayland with physical and virtual monitor output
Now we need to make this virtual display available over VNC which we will access with a VNC client on the tablet. To accomplish this I am using wayvnc but you can use any VNC server package. Install wayvnc
$ sudo apt install wayvnc
Now we will serve our virtual display HEADLESS-1 with wayvnc.
$ wayvnc -o HEADLESS-1 0.0.0.0 5900
You can adjust the port number as per your need. The process from laptop side is done. Now install any VNC software on your tablet. I am using AVNC, which is available on F-Droid. In the VNC software interface, add a new connection with the IP address of your laptop and the port started by wayvnc. Remember, both your laptop and phone need to be on the same Wi-Fi network.
altAVNC interface with the connection details to connect to the virtual monitor.
Save and connect. Now you will be able to see a extended display on your tablet. Enjoy working with multiple screens in a portable setup. Till next time.. Have a great time.

Russell Coker: Server CPU Sockets

I am always looking for ways of increasing the compute power I have at a reasonable price. I am very happy with my HP z840 dual CPU workstation [1] that I m using as a server and my HP z640 single CPU workstation [2]. Both of them were available second hand at quite reasonable prices and could be cheaply upgraded to faster CPUs. But if I can get something a lot faster for a reasonable price then I ll definitely get it. Socket LGA2011-v3 The home server and home workstation I currently use have socket LGA2011-v3 [3] which supports the E5-2699A v4 CPU which gives a rating of 26,939 according to Passmark [4]. That Passmark score is quite decent, you can get CPUs using DDR4 RAM that go up to almost double that but it s a reasonable speed and it works in systems that are readily available at low prices. The z640 is regularly on sale for less than $400AU and the z840 is occasionally below $600. The Dell PowerEdge T430 is an ok dual-CPU tower server using the same socket. One thing that s not well known is that is it limited to something like 135W per CPU when run with two CPUs. So it will work correctly with a single E5-2697A v4 with 145W TDP (I ve tested that) but will refuse to boot with two of them. In my test system I tried replacing the 495W PSUs with 750W PSUs and it made no difference, the motherboard has the limit. With only a single CPU you only get 8/12 DIMM sockets and not all PCIe slots work. There are many second hand T430s on sale with only a single CPU presumably because the T330 sucks. My T430 works fine with a pair of E5-2683 v4 CPUs. The Dell PowerEdge T630 also takes the same CPUs but supports higher TDP than the T430. They also support 18*3.5 disks or 32*2.5 but they are noisy. I wouldn t buy one for home use. AMD There are some nice AMD CPUs manufactured around the same time and AMD has done a better job of making multiple CPUs that fit the same socket. The reason I don t generally use AMD CPUs is that they are used in a minority of the server grade systems so as I want ECC RAM and other server features I generally can t find AMD systems at a reasonable price on ebay etc. There are people who really want second hand server grade systems with AMD CPUs and outbid me. This is probably a region dependent issue, maybe if I was buying in the US I could get some nice workstations with AMD CPUs at low prices. Socket LGA1151 Socket LGA1151 [5] is used in the Dell PowerEdge T330. It only supports 2 memory channels and 4 DIMMs compared to the 4 channels and 8 DIMMs in LGA2011, and it also has a limit of 64G total RAM for most systems and 128G for some systems. By today s standards even 128G is a real limit for server use, DDR4 RDIMMs are about $1/GB and when spending $600+ on system and CPU upgrade you wouldn t want to spend less than $130 on RAM. The CPUs with decent performance for that socket like the i9-9900K aren t supported by the T330 (possibly they don t support ECC RAM). The CPUs that Dell supports perform very poorly. I suspect that Dell deliberately nerfed the T330 to drive sales of the T430. The Lenovo P330 uses socket LGA1151-2 but has the same issues of taking slow CPUs in addition to using UDIMMs which are significantly more expensive on the second hand market. Socket LGA2066 The next Intel socket after LGA2011-v3 is LGA2066 [6]. That is in The Dell Precision 5820 and HP Z4 G4. It takes an i9-10980XE for 32,404 on Passmark or a W-2295 for 30,906. The variant of the Dell 5820 that supports the i9 CPUs doesn t seem to support ECC RAM so it s not a proper workstation. The single thread performance difference between the W-2295 and the E5-2699A v4 is 2640 to 2055, a 28% increase for the W-2295. There are High Frequency Optimized cpus for socket LGA2011-v3 but they all deliver less than 2,300 on the Passmark single-thread tests which is much less than what you can get from socket LGA2066. The W-2295 costs $1000 on ebay and the E5-2699A v4 is readily available for under $400 and a few months ago I got a matched pair for a bit over $400. Note that getting a matched pair of Intel CPUs is a major pain [7]. Comparing sockets LGA2011-v3 and LGA2066 for a single-CPU system is a $300 system (HP x640) + $400 CPU (E5-2699A v4) vs $500 system (Dell Precision 5820) + $1000 CPU (W-2295), so more than twice the price for a 30% performance benefit on some tasks. The LGA2011-v3 and USB-C both launched in 2014 so LGA2011-v3 systems don t have USB-C sockets, a $20 USB-C PCIe card doesn t change the economics. Socket LGA3647 Socket LGA3647 [8] is used in the Dell PowerEdge T440. It supports 6 channels of DDR4 RAM which is a very nice feature for bigger systems. According to one Dell web page the best CPU Dell officially supports for this is the Xeon Gold 5120 which gives performance only slightly better than the E5-2683 v4 which has a low enough TDP that a T430 can run two of them. But according to another Dell web page they support 16 core CPUs which means performance better than a T430 but less than a HP z840. The T440 doesn t seem like a great system, if I got one cheap I could find a use for it but I wouldn t pay the prices that they go for on ebay. The Dell PowerEdge T640 has the same socket and is described as supporting up to 28 core CPUs. But I anticipate that it would be as loud as the T630 and it s also expensive. This socket is also used in the HP Z6 G4 which takes a W-3265 or Xeon Gold 6258R CPU for the high end options. The HP Z6 G4 systems on ebay are all above $1500 and the Xeon Gold 6258R is also over $1000 so while the Xeon Gold 6258R in a Z6 G4 will give 50% better performance on multithreaded operations than the systems I currently have it s costing almost 3* as much. It has 6 DIMM sockets which is a nice improvement over the 4 in the z640. The Z6 G4 takes a maximum of 768G of RAM with the optional extra CPU board (which is very expensive both new and on ebay) compared to my z840 which has 512G and half it s DIMM slots empty. The HP Z8 G4 has the same socket and takes up to 3TB of RAM if used with CPUs that support it (most CPUs only support 768G and you need a M variant to support more). The higher performance CPUs supported in the Z6 G4 and Z8 G4 don t have enough entries in the Passmark database to be accurate, but going from 22 cores in the E5-2699A v4 to 28 in the Xeon Platinum 8180 when using the same RAM technology doesn t seem like a huge benefit. The Z6 and Z8 G4 systems run DDR4 RAM at up to 2666 speed while the z640 and z840 only to 2400, a 10% increase in RAM speed is nice but not a huge difference. I don t think that any socket LGA3647 systems will ever be ones I want to buy. They don t offer much over LGA2011-v3 but are in newer and fancier systems that will go for significantly higher prices. DDR5 I think that DDR5 systems will be my next step up in tower server and workstation performance after the socket LGA2011-v3 systems. I don t think anything less will offer me enough of a benefit to justify a change. I also don t think that they will be in the price range I am willing to pay until well after DDR6 is released, some people are hoping for DDR6 to be released late this year but next year seems more likely. So maybe in 2027 there will be some nice DDR5 systems going cheap. CPU Benchmark Results Here are the benchmark results of CPUs I mentioned in this post according to passmark.com [9]. I didn t reference results of CPUs that only had 1 or 2 results posted as they aren t likely to be accurate.
CPU Single Thread Multi Thread TDP
E5-2683 v4 1,713 17,591 120W
Xeon Gold 5120 1,755 18,251 105W
i9-9900K 2,919 18,152 95W
E5-2697A v4 2,106 21,610 145W
E5-2699A v4 2,055 26,939 145W
W-3265 2,572 30,105 205W
W-2295 2,642 30,924 165W
i9-10980XE 2,662 32,397 165W
Xeon Gold 6258R 2,080 40,252 205W

1 August 2025

Jonathan Dowland: School of Computing Technical Reports

(You wait ages for an archiving blog post and two come along at once!) Between 1969-2019, the Newcastle University School of Computing published a Technical Reports Series. Until 2017-ish, the full list of individually-numbered reports was available on the School's website, as well as full text PDFs for every report. At some time around 2014 I was responsible for migrating the School's website from self-managed to centrally-managed. The driver was to improve the website from the perspective of student recruitment. The TR listings (as well as full listings and texts for awarded PhD theses, MSc dissertations, Director's reports and various others) survived the initial move. After I left (as staff) in 2015, anything not specifically about student recruitment degraded and by 2017 the listings were gone. I've been trying, on and off, to convince different parts of the University to restore and take ownership of these lists ever since. For one reason or another each avenue I've pursued has gone nowhere. Recently the last remaining promising way forward failed, so I gave up and did it myself. The list is now hosted by the Historic Computing Committee, here: https://nuhc.ncl.ac.uk/computing/techreports/ It's not complete (most of the missing entries are towards the end of the run), but it's a start. The approach that finally yielded results was simply scraping the Internet Archive Wayback Machine for various pages from back when the material was represented on the School website, and then filling in the gaps from some other sources. What I envisage in the future: per-page reports with the relevant metadata (including abstracts); authors de-duplicated and cross-referenced; PDFs OCRd; providing access to the whole metadata DB (probably as as lump of JSON); a mechanism for people to report errors; a platform for students to perform data mining projects: perhaps some kind of classification/tagging by automated content analysis; cross-referencing copies of papers in other venues (lots of TRs are pre-prints).

Guido G nther: Free Software Activities July 2025

Another short status update of what happened on my side last month - a lot shorter than usual due to real life events (that will also affect August) but there was some progress on stevia and it landed in Debian too now. See below for details on the above and more: phosh phoc phosh-mobile-settings stevia (formerly phosh-osk-stub) phosh-vala-plugins xdg-desktop-portal-phosh feedbackd-device-themes livi Debian foliate Cellbroadcastd git-buildpackage wayland-protocols Reviews This is not code by me but reviews on other peoples code. The list is (as usual) slightly incomplete. Thanks for the contributions! Help Development If you want to support my work see donations. Comments? Join the Fediverse thread

puer-robustus: My Google Summer of Code '25 at Debian

I ve participated in this year s Google Summer of Code (GSoC) program and have been working on the small (90h) autopkgtests for the rsync package project at Debian.

Writing my proposal Before you can start writing a proposal, you need to select an organization you want to work with. Since many organizations participate in GSoC, I ve used the following criteria to narrow things down for me:
  • Programming language familiarity: For me only Python (preferably) as well as shell and Go projects would have made sense. While learning another programming language is cool, I wouldn t be as effective and helpful to the project as someone who is proficient in the language already.
  • Standing of the organization: Some of the organizations participating in GSoC are well-known for the outstanding quality of the software they produce. Debian is one of them, but so is e.g. the Django Foundation or PostgreSQL. And my thinking was that the higher the quality of the organization, the more there is to learn for me as a GSoC student.
  • Mentor interactions: Apart from the advantage you get from mentor feedback when writing your proposal (more on that further below), it is also helpful to gauge how responsive/helpful your potential mentor is during the application phase. This is important since you will be working together for a period of at least 2 months; if the mentor-student communication doesn t work, the GSoC project is going to be difficult.
  • Free and Open-Source Software (FOSS) communication platforms: I generally believe that FOSS projects should be built on FOSS infrastructure. I personally won t run proprietary software when I want to contribute to FOSS in my spare time.
  • Be a user of the project: As Eric S. Raymond has pointed out in his seminal The Cathedral and the Bazaar 25 years ago
    Every good work of software starts by scratching a developer s personal itch.
Once I had some organizations in mind whose projects I d be interested in working on, I started writing proposals for them. Turns out, I started writing my proposals way too late: In the end I only managed to hand in a single one which is risky. Competition for the GSoC projects is fierce and the more quality (!) proposals you send out, the better your chances are at getting one. However, don t write proposals for the sake of it: Reviewers get way too many AI slop proposals already and you will not do yourself a favor with a low-quality proposal. Take the time to read the instructions/ideas/problem descriptions the project mentors have provided and follow their guidelines. Don t hesitate to reach out to project mentors: In my case, I ve asked Samuel Henrique a few clarification questions whereby the following (email) discussion has helped me greatly in improving my proposal. Once I ve finalized my proposal draft, I ve sent it to Samuel for a review, which again led to some improvements to the final proposal which I ve uploaded to the GSoC program webpage.

Community bonding period Once you get the information that you ve been accepted into the GSoC program (don t take it personally if you don t make it; this was my second attempt after not making the cut in 2024), get in touch with your prospective mentor ASAP. Agree upon a communication channel and some response times. Put yourself in the loop for project news and discussions whatever that means in the context of your organization: In Debian s case this boiled down to subscribing to a bunch of mailing lists and IRC channels. Also make sure to setup a functioning development environment if you haven t done so for writing the proposal already.

Payoneer setup The by far most annoying part of GSoC for me. But since you don t have a choice if you want to get the stipend, you will need to signup for an account at Payoneer. In this iteration of GSoC all participants got a personalized link to open a Payoneer account. When I tried to open an account by following this link, I got an email after the registration and email verification that my account is being blocked because Payoneer deems the email adress I gave a temporary one. Well, the email in question is most certainly anything but temporary, so I tried to get in touch with the Payoneer support - and ended up in an LLM-infused kafkaesque support hell. Emails are answered by an LLM which for me meant utterly off-topic replies and no help whatsoever. The Payoneer website offers a real-time chat, but it is yet another instance of a bullshit-spewing LLM bot. When I at last tried to call them (the support lines are not listed on the Payoneer website but were provided by the GSoC program), I kid you not, I was being told that their platform is currently suffering from technical problems and was hung up on. Only thanks to the swift and helpful support of the GSoC administrators (who get priority support from Payoneer) I was able to setup a Payoneer account in the end. Apart from showing no respect to customers, Payoneer is also ripping them off big time with fees (unless you get paid in USD). They charge you 2% for currency conversions to EUR on top of the FX spread they take. What worked for me to avoid all of those fees, was to open a USD account at Wise and have Payoneer transfer my GSoC stipend in USD to that account. Then I exchanged the USD to my local currency at Wise for significantly less than Payoneer would have charged me. Also make sure to close your Payoneer account after the end of GSoC to avoid their annual fee.

Project work With all this prelude out of the way, I can finally get to the actual work I ve been doing over the course of my GSoC project.

Background The upstream rsync project generally sees little development. Nonetheless, they released version 3.4.0 including some CVE fixes earlier this year. Unfortunately, their changes broke the -H flag. Now, Debian package maintainers need to apply those security fixes to the package versions in the Debian repositories; and those are typically a bit older. Which usually means that the patches cannot be applied as is but will need some amendments by the Debian maintainers. For these cases it is helpful to have autopkgtests defined, which check the package s functionality in an automated way upon every build. The question then is, why should the tests not be written upstream such that regressions are caught in the development rather than the distribution process? There s a lot to say on this question and it probably depends a lot on the package at hand, but for rsync the main benefits are twofold:
  1. The upstream project mocks the ssh connection over which rsync is most typically used. Mocking is better than nothing but not the real thing. In addition to being a more realisitic test scenario for the typical rsync use case, involving an ssh server in the test would automatically extend the overall resilience of Debian packages as now new versions of the openssh-server package in Debian benefit from the test cases in the rsync reverse dependency.
  2. The upstream rsync test framework is somewhat idiosyncratic and difficult to port to reimplementations of rsync. Given that the original rsync upstream sees little development, an extensive test suit further downstream can serve as a threshold for drop-in replacements for rsync.

Goal(s) At the start of the project, the Debian rsync package was just running (a part of) the upstream tests as autopkgtests. The relevant snippet from the build log for the rsync_3.4.1+ds1-3 package reads:
114s ------------------------------------------------------------
114s ----- overall results:
114s 36 passed
114s 7 skipped
Samuel and I agreed that it would be a good first milestone to make the skipped tests run. Afterwards, I should write some rsync test cases for local calls, i.e. without an ssh connection, effectively using rsync as a more powerful cp. And once that was done, I should extend the tests such that they run over an active ssh connection. With these milestones, I went to work.

Upstream tests Running the seven skipped upstream tests turned out to be fairly straightforward:
  • Two upstream tests concern access control lists and extended filesystem attributes. For these tests to run they rely on functionality provided by the acl and xattr Debian packages. Adding those to the Build-Depends list in the debian/control file of the rsync Debian package repo made them run.
  • Four upstream tests required root privileges to run. The autopkgtest tool knows the needs-root restriction for that reason. However, Samuel and I agreed that the tests should not exclusively run with root privileges. So, instead of just adding the restiction to the existing autopkgtest test, we created a new one which has the needs-root restriction and runs the upstream-tests-as-root script - which is nothing else than a symlink to the existing upstream-tests script.
The commits to implement these changes can be found in this merge request. The careful reader will have noticed that I only made 2 + 4 = 6 upstream test cases run out of 7: The leftover upstream test is checking the functionality of the --ctimes rsync option. In the context of Debian, the problem is that the Linux kernel doesn t have a syscall to set the creation time of a file. As long as that is the case, this test will always be skipped for the Debian package.

Local tests When it came to writing Debian specific test cases I started of a completely clean slate. Which is a blessing and a curse at the same time: You have full flexibility but also full responsibility. There were a few things to consider at this point in time:
  • Which language to write the tests in? The programming language I am most proficient in is Python. But testing a CLI tool in Python would have been weird: it would have meant that I d have to make repeated subprocess calls to run rsync and then read from the filesystem to get the file statistics I want to check. Samuel suggested I stick with shell scripts and make use of diffoscope - one of the main tools used and maintained by the Reproducible Builds project - to check whether the file contents and file metadata are as expected after rsync calls. Since I did not have good reasons to use bash, I ve decided to write the scripts to be POSIX compliant.
  • How to avoid boilerplate? If one makes use of a testing framework, which one? Writing the tests would involve quite a bit of boilerplate, mostly related to giving informative output on and during the test run, preparing the file structure we want to run rsync on, and cleaning the files up after the test has run. It would be very repetitive and in violation of DRY to have the code for this appear in every test. Good testing frameworks should provide convenience functions for these tasks. shunit2 comes with those functions, is packaged for Debian, and given that it is already being used in the curl project, I decided to go with it.
  • Do we use the same directory structure and files for every test or should every test have an individual setup? The tradeoff in this question being test isolation vs. idiosyncratic code. If every test has its own setup, it takes a) more work to write the test and b) more work to understand the differences between tests. However, one can be sure that changes to the setup in one test will have no side effects on other tests. In my opinion, this guarantee was worth the additional effort in writing/reading the tests.
Having made these decisions, I simply started writing tests and ran into issues very quickly.

rsync and subsecond mtime diffs When testing the rsync --times option, I observed a weird phenomenon: If the source and destination file have modification times which differ only in the nanoseconds, an rsync --times call will not synchronize the modification times. More details about this behavior and examples can be found in the upstream issue I raised. In the Debian tests we had to occasionally work around this by setting the timestamps explicitly with touch -d.
diffoscope regression In one test case, I was expecting a difference in the modification times but diffoscope would not report a diff. After a good amount of time spent on debugging the problem (my default, and usually correct, assumption is that something about my code is seriously broken if I run into issues like that), I was able to show that diffoscope only displayed this behavior in the version in the unstable suite, not on Debian stable (which I am running on my development machine). Since everything pointed to a regression in the diffoscope project and with diffoscope being written in Python, a language I am familiar with, I wanted to spend some time investigating (and hopefully fixing) the problem. Running git bisect on the diffoscope repo helped me in identifying the commit which introduced the regression: The commit contained an optimization via an early return for bit-by-bit identical files. Unfortunately, the early return also caused an explicitly requested metadata comparison (which could be different between the files) to be skipped. With a nicely diagnosed issue like that, I was able to go to a local hackerspace event, where people work on FOSS together for an evening every month. In a group, we were able to first, write a test which showcases the broken behavior in the latest diffoscope version, and second, make a fix to the code such that the same test passes going forward. All details can be found in this merge request.
shunit2 failures At some point I had a few autopkgtests setup and passing, but adding a new one would throw me totally inexplicable errors. After trying to isolate the problem as much as possible, it turns out that shunit2 doesn t play well together we the -e shell option. The project mentions this in the release notes for the 2.1.8 version1, but in my opinion a constraint this severe should be featured much more prominently, e.g. in the README.

Tests over an ssh connection The centrepiece of this project; everything else has in a way only been preparation for this. Obviously, the goal was to reuse the previously written local tests in some way. Not only because lazy me would have less work to do this way, but also because of a reduced long-term maintenance burden of one rather than two test sets. As it turns out, it is actually possible to accomplish that: The remote-tests script doesn t do much apart from starting an ssh server on localhost and running the local-tests script with the REMOTE environment variable set. The REMOTE environment variable changes the behavior of the local-tests script in such a way that it prepends "$REMOTE": to the destination of the rsync invocations. And given that we set REMOTE=rsync@localhost in the remote-tests script, local-tests copies the files to the exact same locations as before, just over ssh. The implementational details for this can be found in this merge request.

proposed-updates Most of my development work on the Debian rsync package took place during the Debian freeze as the release of Debian Trixie is just around the corner. This means that uploading by Debian Developers (DD) and Debian Maintainers (DM) to the unstable suite is discouraged as it makes migrating the packages to testing more difficult for the Debian release team. If DDs/DMs want to have the package version in unstable migrated to testing during the freeze they have to file an unblock request. Samuel has done this twice (1, 2) for my work for Trixie but has asked me to file the proposed-updates request for current stable (i.e. Debian Bookworm) myself after I ve backported my tests to bookworm.

Unfinished business To run the upstream tests which check access control list and extended file system attributes functionality, I ve added the acl and xattr packages to Build-Depends in debian/control. This, however, will only make the packages available at build time: If Debian users install the rsync package, the acl and xattr packages will not be installed alongside it. For that, the dependencies would have to be added to Depends or Suggests in debian/control. Depends is probably to strong of a relation since rsync clearly works well in practice without, but adding them to Suggests might be worthwhile. A decision on this would involve checking, what happens if rsync is called with the relevant options on a host machine which has those packages installed, but where the destination machine lacks them. Apart from the issue described above, the 15 tests I managed to write are are a drop in the water in light of the infinitude of rsync options and their combinations. Most glaringly, not all options of the --archive option are covered separately (which would help indicating what code path of rsync broke in a regression). To increase the likelihood of catching regressions with the autopkgtests, the test coverage should be extended in the future.

Conclusion Generally, I am happy with my contributions to Debian over the course of my small GSoC project: I ve created an extensible, easy to understand, and working autopkgtest setup for the Debian rsync package. There are two things which bother me, however:
  1. In hindsight, I probably shouldn t have gone with shunit2 as a testing framework. The fact that it behaves erratically with the -e flag is a serious drawback for a shell testing framework: You really don t want a shell command to fail silently and the test to continue running.
  2. As alluded to in the previous section, I m not particularly proud of the number of tests I managed to write.
On the other hand, finding and fixing the regression in diffoscope - while derailing me from the GSoC project itself - might have a redeeming quality.

DebConf25 By sheer luck I happened to work on a GSoC project at Debian over a time period during which the annual Debian conference would take place close enough to my place of residence. Samuel pointed the opportunity to attend DebConf out to me during the community bonding period and since I could make time for the event in my schedule, I signed up. DebConf was a great experience which - aside from gaining more knowledge about Debian development - allowed me to meet the actual people usually hidden behind email adresses and IRC nicks. I can wholeheartedly recommend attending a DebConf to every interested Debian user! For those who have missed this year s iteration of the conference, I can recommend the following recorded talks: While not featuring as a keynote speaker (understandably so as the newcomer to Debian community that I am), I could still contribute a bit to the conference program.

GSoC project presentation The Debian Outreach team has scheduled a session in which all GSoC and Outreachy students over the past year had the chance to present their work in a lightning talk. The session has been recorded and is available online, just like my slides and the source for them.

Debian install workshop Additionally, with so many Debian experts gathering in one place while KDE s End of 10 campaign is ongoing, I felt it natural to organize a Debian install workhop. In hindsight I can say that I underestimated how much work it would be, especially for me who does not speak a word of French. But although the turnout of people who wanted us to install Linux on their machines was disappointingly low, it was still worth it: Not only because the material in the repo can be helpful to others planning install workshops but also because it was nice to meet a) the person behind the Debian installer images and b) the local Brest/Finist re Linux user group as well as the motivated and helpful people at Infini.

Credits I want to thank the Open Source team at Google for organizing GSoC: The highly structured program with a one-to-one mentorship is a great avenue to start contributing to well established and at times intimidating FOSS projects. And as much as I disagree with Google s surveillance capitalist business model, I have to give it to them that the company at least takes its responsibility for FOSS (somewhat) seriously - unlike many other businesses which rely on FOSS and choose to freeride of it. Big thanks to the Debian community! I ve experienced nothing but friendliness in my interactions with the community. And lastly, the biggest thanks to my GSoC mentor Samuel Henrique. He has dealt patiently and competently with all my stupid newbie questions. His support enabled me to make - albeit small - contributions to Debian. It has been a pleasure to work with him during GSoC and I m looking forward to working together with him in the future.

  1. Obviously, I ve only read them after experiencing the problem.

31 July 2025

Matthew Garrett: Secure boot certificate rollover is real but probably won't hurt you

LWN wrote an article which opens with the assertion "Linux users who have Secure Boot enabled on their systems knowingly or unknowingly rely on a key from Microsoft that is set to expire in September". This is, depending on interpretation, either misleading or just plain wrong, but also there's not a good source of truth here, so.

First, how does secure boot signing work? Every system that supports UEFI secure boot ships with a set of trusted certificates in a database called "db". Any binary signed with a chain of certificates that chains to a root in db is trusted, unless either the binary (via hash) or an intermediate certificate is added to "dbx", a separate database of things whose trust has been revoked[1]. But, in general, the firmware doesn't care about the intermediate or the number of intermediates or whatever - as long as there's a valid chain back to a certificate that's in db, it's going to be happy.

That's the conceptual version. What about the real world one? Most x86 systems that implement UEFI secure boot have at least two root certificates in db - one called "Microsoft Windows Production PCA 2011", and one called "Microsoft Corporation UEFI CA 2011". The former is the root of a chain used to sign the Windows bootloader, and the latter is the root used to sign, well, everything else.

What is "everything else"? For people in the Linux ecosystem, the most obvious thing is the Shim bootloader that's used to bridge between the Microsoft root of trust and a given Linux distribution's root of trust[2]. But that's not the only third party code executed in the UEFI environment. Graphics cards, network cards, RAID and iSCSI cards and so on all tend to have their own unique initialisation process, and need board-specific drivers. Even if you added support for everything on the market to your system firmware, a system built last year wouldn't know how to drive a graphics card released this year. Cards need to provide their own drivers, and these drivers are stored in flash on the card so they can be updated. But since UEFI doesn't have any sandboxing environment, those drivers could do pretty much anything they wanted to. Someone could compromise the UEFI secure boot chain by just plugging in a card with a malicious driver on it, and have that hotpatch the bootloader and introduce a backdoor into your kernel.

This is avoided by enforcing secure boot for these drivers as well. Every plug-in card that carries its own driver has it signed by Microsoft, and up until now that's been a certificate chain going back to the same "Microsoft Corporation UEFI CA 2011" certificate used in signing Shim. This is important for reasons we'll get to.

The "Microsoft Windows Production PCA 2011" certificate expires in October 2026, and the "Microsoft Corporation UEFI CA 2011" one in June 2026. These dates are not that far in the future! Most of you have probably at some point tried to visit a website and got an error message telling you that the site's certificate had expired and that it's no longer trusted, and so it's natural to assume that the outcome of time's arrow marching past those expiry dates would be that systems will stop booting. Thankfully, that's not what's going to happen.

First up: if you grab a copy of the Shim currently shipped in Fedora and extract the certificates from it, you'll learn it's not directly signed with the "Microsoft Corporation UEFI CA 2011" certificate. Instead, it's signed with a "Microsoft Windows UEFI Driver Publisher" certificate that chains to the "Microsoft Corporation UEFI CA 2011" certificate. That's not unusual, intermediates are commonly used and rotated. But if we look more closely at that certificate, we learn that it was issued in 2023 and expired in 2024. Older versions of Shim were signed with older intermediates. A very large number of Linux systems are already booting certificates that have expired, and yet things keep working. Why?

Let's talk about time. In the ways we care about in this discussion, time is a social construct rather than a meaningful reality. There's no way for a computer to observe the state of the universe and know what time it is - it needs to be told. It has no idea whether that time is accurate or an elaborate fiction, and so it can't with any degree of certainty declare that a certificate is valid from an external frame of reference. The failure modes of getting this wrong are also extremely bad! If a system has a GPU that relies on an option ROM, and if you stop trusting the option ROM because either its certificate has genuinely expired or because your clock is wrong, you can't display any graphical output[3] and the user can't fix the clock and, well, crap.

The upshot is that nobody actually enforces these expiry dates - here's the reference code that disables it. In a year's time we'll have gone past the expiration date for "Microsoft Windows UEFI Driver Publisher" and everything will still be working, and a few months later "Microsoft Windows Production PCA 2011" will also expire and systems will keep booting Windows despite being signed with a now-expired certificate. This isn't a Y2K scenario where everything keeps working because people have done a huge amount of work - it's a situation where everything keeps working even if nobody does any work.

So, uh, what's the story here? Why is there any engineering effort going on at all? What's all this talk of new certificates? Why are there sensationalist pieces about how Linux is going to stop working on old computers or new computers or maybe all computers?

Microsoft will shortly start signing things with a new certificate that chains to a new root, and most systems don't trust that new root. System vendors are supplying updates[4] to their systems to add the new root to the set of trusted keys, and Microsoft has supplied a fallback that can be applied to all systems even without vendor support[5]. If something is signed purely with the new certificate then it won't boot on something that only trusts the old certificate (which shouldn't be a realistic scenario due to the above), but if something is signed purely with the old certificate then it won't boot on something that only trusts the new certificate.

How meaningful a risk is this? We don't have an explicit statement from Microsoft as yet as to what's going to happen here, but we expect that there'll be at least a period of time where Microsoft signs binaries with both the old and the new certificate, and in that case those objects should work just fine on both old and new computers. The problem arises if Microsoft stops signing things with the old certificate, at which point new releases will stop booting on systems that don't trust the new key (which, again, shouldn't happen). But even if that does turn out to be a problem, nothing is going to force Linux distributions to stop using existing Shims signed with the old certificate, and having a Shim signed with an old certificate does nothing to stop distributions signing new versions of grub and kernels. In an ideal world we have no reason to ever update Shim[6] and so we just keep on shipping one signed with two certs.

If there's a point in the future where Microsoft only signs with the new key, and if we were to somehow end up in a world where systems only trust the old key and not the new key[7], then those systems wouldn't boot with new graphics cards, wouldn't be able to run new versions of Windows, wouldn't be able to run any Linux distros that ship with a Shim signed only with the new certificate. That would be bad, but we have a mechanism to avoid it. On the other hand, systems that only trust the new certificate and not the old one would refuse to boot older Linux, wouldn't support old graphics cards, and also wouldn't boot old versions of Windows. Nobody wants that, and for the foreseeable future we're going to see new systems continue trusting the old certificate and old systems have updates that add the new certificate, and everything will just continue working exactly as it does now.

Conclusion: Outside some corner cases, the worst case is you might need to boot an old Linux to update your trusted keys to be able to install a new Linux, and no computer currently running Linux will break in any way whatsoever.

[1] (there's also a separate revocation mechanism called SBAT which I wrote about here, but it's not relevant in this scenario)

[2] Microsoft won't sign GPLed code for reasons I think are unreasonable, so having them sign grub was a non-starter, but also the point of Shim was to allow distributions to have something that doesn't change often and be able to sign their own bootloaders and kernels and so on without having to have Microsoft involved, which means grub and the kernel can be updated without having to ask Microsoft to sign anything and updates can be pushed without any additional delays

[3] It's been a long time since graphics cards booted directly into a state that provided any well-defined programming interface. Even back in 90s, cards didn't present VGA-compatible registers until card-specific code had been executed (hence DEC Alphas having an x86 emulator in their firmware to run the driver on the card). No driver? No video output.

[4] There's a UEFI-defined mechanism for updating the keys that doesn't require a full firmware update, and it'll work on all devices that use the same keys rather than being per-device

[5] Using the generic update without a vendor-specific update means it wouldn't be possible to issue further updates for the next key rollover, or any additional revocation updates, but I'm hoping to be retired by then and I hope all these computers will also be retired by then

[6] I said this in 2012 and it turned out to be wrong then so it's probably wrong now sorry, but at least SBAT means we can revoke vulnerable grubs without having to revoke Shim

[7] Which shouldn't happen! There's an update to add the new key that should work on all PCs, but there's always the chance of firmware bugs

comment count unavailable comments

Simon Josefsson: Independently Reproducible Git Bundles

The gnulib project publish a git bundle as a stable archival copy of the gnulib git repository once in a while. Why? We don t know exactly what this may be useful for, but I m promoting for this to see if we can establish some good use-case. A git bundle may help to establish provinence in case of an attack on the Savannah hosting platform that compromise the gnulib git repository. Another use is in the Debian gnulib package: that gnulib bundle is git cloned when building some Debian packages, to get to exactly the gnulib commit used by each upstream project see my talk on gnulib at Debconf24 and this approach reduces the amount of vendored code that is part of Debian s source code, which is relevant to mitigate XZ-style attacks. The first time we published the bundle, I wanted it to be possible to re-create it bit-by-bit identically by others. At the time I discovered a well-written blog post by Paul Beacher on reproducible git bundles and thought he had solved the problem for me. Essentially it boils down to disable threading during compression when producing the bundle, and his final example show this results in a predictable bit-by-bit identical output:
$ for i in $(seq 1 100); do \
> git -c 'pack.threads=1' bundle create -q /tmp/bundle-$i --all; \
> done
$ md5sum /tmp/bundle-*   cut -f 1 -d ' '   uniq -c
    100 4898971d4d3b8ddd59022d28c467ffca
So what remains to be said about this? It seems reproducability goes deeper than that. One desirable property is that someone else should be able to reproduce the same git bundle, and not only that a single individual is able to reproduce things on one machine. It surprised me to see that when I ran the same set of commands on a different machine (started from a fresh git clone), I got a different checksum. The different checksums occured even when nothing had been committed on the server side between the two runs. I thought the reason had to do with other sources of unpredictable data, and I explored several ways to work around this but eventually gave up. I settled for the following sequence of commands:
REV=ac9dd0041307b1d3a68d26bf73567aa61222df54 # master branch commit to package
git clone https://git.savannah.gnu.org/git/gnulib.git
cd gnulib
git fsck # attempt to validate input
# inspect that the new tree matches a trusted copy
git checkout -B master $REV # put $REV at master
for b in $(git branch -r   grep origin/stable-   sort --version-sort); do git checkout $ b#origin/ ; done
git remote remove origin # drop some unrelated branches
git gc --prune=now # drop any commits after $REV
git -c 'pack.threads=1' bundle create gnulib.bundle --all
V=$(env TZ=UTC0 git show -s --date=format:%Y%m%d --pretty=%cd master)
mv gnulib.bundle gnulib-$V.bundle
build-aux/gnupload --to ftp.gnu.org:gnulib gnulib-$V.bundle
At the time it felt more important to publish something than to reach for perfection, so we did so using the above snippet. Afterwards I reached out to the git community on this and there were good discussion about my challenge. At the end of that thread you see that I was finally able to reproduce a bit-by-bit identical bundles from two different clones, by using an intermediate git -c pack.threads=1 repack -adF step. I now assume that the unpredictable data I got earlier was introduced during the git clone steps, compressing the pack differently each time due to threaded compression. The outcome could also depend on what content the server provided, so if someone ran git gc, git repack on the server side things would change for the user, even if the user forced threading to 1 during cloning more experiments on what kind of server-side alterations results in client-side differences would be good research. A couple of months passed and it is now time to publish another gnulib bundle somewhat paired to the bi-yearly stable gnulib branches so let s walk through the commands and explain what they do. First clone the repository:
REV=225973a89f50c2b494ad947399425182dd42618c   # master branch commit to package
S1REV=475dd38289d33270d0080085084bf687ad77c74d # stable-202501 branch commit
S2REV=e8cc0791e6bb0814cf4e88395c06d5e06655d8b5 # stable-202507 branch commit
git clone https://git.savannah.gnu.org/git/gnulib.git
cd gnulib
git fsck # attempt to validate input
I believe the git fsck will validate that the chain of SHA1 commits are linked together, preventing someone from smuggling in unrelated commits earlier in the history without having to do SHA1 collision. SHA1 collisions are economically feasible today, so this isn t much of a guarantee of anything though.
git checkout -B master $REV # put $REV at master
# Add all stable-* branches locally:
for b in $(git branch -r   grep origin/stable-   sort --version-sort); do git checkout $ b#origin/ ; done
git checkout -B stable-202501 $S1REV
git checkout -B stable-202507 $S2REV
git remote remove origin # drop some unrelated branches
git gc --prune=now # drop any unrelated commits, not clear this helps
This establish a set of branches pinned to particular commits. The older stable-* branches are no longer updated, so they shouldn t be moving targets. In case they are modified in the future, the particular commit we used will be found in the official git bundle.
time git -c pack.threads=1 repack -adF
That s the new magic command to repack and recompress things in a hopefully more predictable way. This leads to a 72MB git pack under .git/objects/pack/ and a 62MB git bundle. The runtime on my laptop is around 5 minutes. I experimented with -c pack.compression=1 and -c pack.compression=9 but the size was roughly the same; 76MB and 66MB for level 1 and 72MB and 62MB for level 9. Runtime still around 5 minutes. Git uses zlib by default, which isn t the most optimal compression around. I tried -c pack.compression=0 and got a 163MB git pack and a 153MB git bundle. The runtime is still around 5 minutes, indicating that compression is not the bottleneck for the git repack command. That 153MB uncompressed git bundle compresses to 48MB with gzip default settings and 46MB with gzip -9; to 39MB with zst defaults and 34MB with zst -9; and to 28MB using xz defaults with a small 26MB using xz -9. Still the inconvenience of having to uncompress a 30-40MB archive into
the much larger 153MB is probably not worth the savings compared to
shipping and using the (still relatively modest) 62MB git bundle. Now finally prepare the bundle and ship it:
git -c 'pack.threads=1' bundle create gnulib.bundle --all
V=$(env TZ=UTC0 git show -s --date=format:%Y%m%d --pretty=%cd master)
mv gnulib.bundle gnulib-$V.bundle
build-aux/gnupload --to ftp.gnu.org:gnulib gnulib-$V.bundle
Yay! Another gnulib git bundle snapshot is available from
https://ftp.gnu.org/gnu/gnulib/. The essential part of the git repack command is the -F parameter. In the thread -f was suggested, which translates into the git pack-objects --no-reuse-delta parameter:
--no-reuse-delta
When creating a packed archive in a repository that has existing packs, the command reuses existing deltas. This sometimes results in a slightly suboptimal pack. This flag tells the command not to reuse existing deltas but compute them from scratch.
When reading the man page, I though that using -F which translates into --no-reuse-object would be slightly stronger:
--no-reuse-object
This flag tells the command not to reuse existing object data at all, including non deltified object, forcing recompression of everything. This implies --no-reuse-delta. Useful only in the obscure case where wholesale enforcement of a different compression level on the packed data is desired.
On the surface, without --no-reuse-objects, some amount of earlier compression could taint the final result. Still, I was able to get bit-by-bit identical bundles by using -f so possibly reaching for -F is not necessary. All the commands were done using git 2.51.0 as packaged by Guix. I fear the result may be different with other git versions and/or zlib libraries. I was able to reproduce the same bundle on a Trisquel 12 aramo (derived from Ubuntu 22.04) machine, which uses git 2.34.1. This suggests there is some chances of this being possible to reproduce in 20 years time. Time will tell. I also fear these commands may be insufficient if something is moving on the server-side of the git repository of gnulib (even just something simple as a new commit), I tried to make some experiments with this but let s aim for incremental progress here. At least I have now been able to reproduce the same bundle on different machines, which wasn t the case last time. Happy Reproducible Git Bundle Hacking!

29 July 2025

Christoph Berg: The Debian Conference 2025 in Brest

It's Sunday and I'm now sitting in the train from Brest to Paris where I will be changing to Germany, on the way back from the annual Debian conference. A full week of presentations, discussions, talks and socializing is laying behind me and my head is still spinning from the intensity.
Pollito and the gang of DebConf mascots wearing their conference badgesPollito and the gang of DebConf mascots wearing their conference badges (photo: Christoph Berg)
Sunday, July 13th It started last Sunday with traveling to the conference. I got on the Eurostar in Duisburg and we left on time, but even before reaching Cologne, the train was already one hour delayed for external reasons, collecting yet another hour between Aachen and Liege for its own technical problems. "The train driver is working on trying to fix the problem." My original schedule had well over two hours for changing train stations in Paris, but being that late, I missed the connection to Brest in Montparnasse. At least in the end, the total delay was only one hour when finally arriving at the destination. Due to the French julliet quatorze fireworks approaching, buses in Brest were rerouted, but I managed to catch the right bus to the conference venue, already meeting a few Debian people on the way. The conference was hosted at the IMT Atlantique Brest campus, giving the event a nice university touch. I arrived shortly after 10 in the evening and after settling down a bit, got on one of the "magic" buses for transportation to the camping site where half of the attendees where stationed. I shared a mobile home with three other Debianites, where I got a small room for myself. Monday, July 14th Next morning, we took the bus back to the venue with a small breakfast and the opening session where Enrico Zini invited me to come to his and Nicolas Dandrimont's session about Debian community governance and curation, which I gladly did. Many ideas about conflict moderation and community steering were floated around. I hope some of that can be put into effect to make flamewars on the mailing lists less heated and more directed. After that, I attended Olly Betts' "Stemming with Snowball" session, which is the stemmer used also in PostgreSQL. Text search is one of the areas in PostgreSQL that I never really looked closely at, including the integration into the postgresql-common package, so it was nice to get more information about that. In preparation for the conference, a few of us Ham radio operators in Debian had decided to bring some radio gear to DebConf this year in order to perhaps spark more interest for our hobby among the fellow geeks. In the afternoon after the talks, I found a quieter spot just outside of the main hall and set up a shortwave antenna by attaching a 10m mast to one of the park benches there. The 40m band was still pretty much closed, but I could work a few stations from England, just across the channel from Bretagne, answering questions from interested passing-by Debian people between the contacts. Over time, the band opened and more European stations got into the log.
F/DF7CB in Brest (photo: Evangelos Ribeiro Tzaras)
Tuesday, July 15th Tuesday started with Helmut Grohne's session about "Reviving (un)schroot". The schroot program has been Debian's standard way of managing build chroots for a long time, but it is more and more being regarded as obsolete with all kinds of newer containerization and virtualization technologies taking over. Since many bits of Debian infrastructure depend on schroot, and its user interface is still very useful, Helmut reimplemented it using Linux namespaces and the "unshare" systemcall. I had already worked with him at the Hamburg Minidebconf to replace the apt.postgresql.org buildd machinery with the new system, but we were not quite there yet (network isolation is nice, but we still sometimes need proper networking), so it was nice to see the effort is still progressing and I will give his new scripts a try when I'm back home. Next, Stefano Rivera and Colin Watson presented Debusine, a new package repository and workflow management system. It looks very promising for anyone running their own repository, so perhaps yet another bit of apt.postgresql.org infrastructure to replace in the future. After that, I went to the Debian LTS BoF session by Santiago Ruano Rinc n and Bastien Roucari s - Debian releases plus LTS is what we are covering with apt.postgresql.org. Then there were bits from the DPL (Debian Project Leader), and a session moderated by Stefano Rivera interesting to me as a member of the Debian Technical Committee on the future structure of the packages required for cross-building in Debian, a topic which had been brought to TC a while ago. I am happy that we could resolve the issue without having to issue a formal TC ruling as the involved parties (kernel, glibc, gcc and the cross-build people) found a promising way forward themselves. DebConf is really a good way to get such issues unstuck. Ten years ago at the 2015 Heidelberg DebConf, Enrico had given a seminal "Semi-serious stand-up comedy" talk, drawing parallels between the Debian Open Source community and the BDSM community - "People doing things consensually together". (Back then, the talk was announced as "probably unsuitable for people of all ages".) With his unique presentation style and witty insights, the session made a lasting impression on everyone attending. Now, ten years later (and he and many in the audience being ten years older), he gave an updated version of it. We are now looking forward to the sequel in 2035. The evening closed with the famous DebConf tradition of the Cheese & Wine party in a old fort next to the coast, just below the conference venue. Even when he's a fellow Debian Developer, Ham and also TC member, I had never met Paul Tagliamonte in person before, but we spent most of the evening together geeking out on all things Debian and Ham radio.
The northern coast of Ushant (photo: Christoph Berg)
Wednesday, July 16th Wednesday already marked the end of the first half of the week, the day of the day trips. I had chosen to go to Ouessant island (Ushant in English) which marks the Western end of French mainland and hosts one of the lighthouses yielding the way into the English channel. The ferry trip included surprisingly big waves which left some participants seasick, but everyone recovered fast. After around one and a half hours we arrived, picked up the bicycles, and spent the rest of the day roaming the island. The weather forecast was originally very cloudy and 18 C, but over noon this turned into sunny and warm, so many got an unplanned sunburn. I enjoyed the trip very much - it made up for not having time visiting the city during the week. After returning, we spent the rest of the evening playing DebConf's standard game, Mao (spoiler alert: don't follow the link if you ever intend to play).
Having a nice day (photo: Christoph Berg)
Thursday, July 17th The next day started with the traditional "Meet the Technical Committee" session. This year, we trimmed the usual slide deck down to remove the boring boilerplate parts, so after a very short introduction to the work of the committee by our chairman Matthew Vernon, we opened up the discussion with the audience, with seven (out of 8) TC members on stage. I think the format worked very well, with good input from attendees. Next up was "Don't fear the TPM" by Jonathan McDowell. A common misconception in the Free Software community is that the TPM is evil DRM hardware working against the user, but while it could be used in theory that way, the necessary TPM attestations seem to impossible to attain in practice, so that wouldn't happen anyway. Instead, it is a crypto coprocessor present in almost all modern computers that can be used to hold keys, for example to be used for SSH. It will also be interesting to research if we can make use of it for holding the Transparent Data Encryption keys for CYBERTEC's PostgreSQL Enterprise Edition. Aigars Mahinovs then directed everyone in place for the DebConf group picture, and Lucas Nussbaum started a discussion about archive-wide QA tasks in Debian, an area where I did a lot of work in the past and that still interests me. Antonio Terceiro and Paul Gevers followed up with techniques to track archive-wide rebuilding and testing of packages and in turn filing a lot of bugs to track the problems. The evening ended with the conference dinner, again in the fort close by the coast. DebConf is good for meeting new people, and I incidentally ran into another Chris, who happened to be one of the original maintainers of pgaccess, the pre-predecessor of today's pgadmin. I admit still missing this PostgreSQL frontend for its simplicity and ability to easily edit table data, but it disappeared around 2004. Friday, July 18th On Friday, I participated in discussion sessions around contributors.debian.org (PostgreSQL is planning to set up something similar) and the New Member process which I had helped to run and reform a decade or two ago. Agathe Porte (also a Ham radio operator, like so many others at the conference I had no idea of) then shared her work on rust-rewriting the slower parts of Lintian, the Debian package linter. Craig Small talked about "Free as in Bytes", the evolution of the Linux procps free command. Over the time and many kernel versions, the summary numbers printed became better and better, but there will probably never be a version that suits all use cases alike. Later over dinner, Craig (who is also a TC member) and I shared our experiences with these numbers and customers (not) understanding them. He pointed out that for PostgreSQL and looking at used memory in the presence of large shared memory buffers, USS (unique set size) and PSS (proportional set size) should be more realistic numbers than the standard RSS (resident set size) that the top utility is showing by default. Antonio Terceiro and Paul Gevers again joined to lead a session, now on ci.debian.net and autopkgtest, the test driver used for running tests on packages after then have been installed on a system. The PostgreSQL packages are heavily using this to make sure no regressions creep in even after builds have successfully completed and test re-runs are rescheduled periodically. The day ended with Bdale Garbee's electronics team BoF and Paul Tagliamonte and me setting up the radio station in the courtyard, again answering countless questions about ionospheric conditions and operating practice. Saturday, July 19th Saturday was the last conference day. In the first session, Nikos Tsipinakis and Federico Vaga from CERN announced that the LHC will be moving to Debian for the accelerator's frontend computers in their next "long shutdown" maintenance period in the next year. CentOS broke compatibility too often, and Debian trixie together with the extended LTS support will cover the time until the next long shutdown window in 2035, until when the computers should have all been replaced with newer processors covering higher x86_64 baseline versions. The audience was very delighted to hear that Debian is now also being used in this prestige project. Ben Hutchings then presented new Linux kernel features. Particularly interesting for me was the support for atomic writes spanning more than one filesystem block. When configured correctly, this would mean PostgreSQL didn't have to record full-page images in the WAL anymore, increasing throughput and performance. After that, the Debian ftp team discussed ways to improve review of new packages in the archive, and which of their processes could be relaxed with new US laws around Open Source and cryptography algorithms export. Emmanuel Arias led a session on Salsa CI, Debian's Gitlab instance and standard CI pipeline. (I think it's too slow, but the runners are not under their control.) Julian Klode then presented new features in APT, Debian's package manager. I like the new display format (and a tiny bit of that is also from me sending in wishlist bugs). In the last round of sessions this week, I then led the Ham radio BoF with an introduction into the hobby and how Debian can be used. Bdale mentioned that the sBitx family of SDR radios is natively running Debian, so stock packages can be used from the radio's touch display. We also briefly discussed his involvement in ARDC and the possibility to get grants from them for Ham radio projects. Finally, DebConf wrapped up with everyone gathering in the main auditorium and cheering the organizers for making the conference possible and passing Pollito, the DebConf mascot, to the next organizer team.
Pollito on stage (photo: Christoph Berg)
Sunday, July 20th Zoom back to the train: I made it through the Paris metro and I'm now on the Eurostar back to Germany. It has been an intense week with all the conference sessions and meeting all the people I had not seen so long. There are a lot of new ideas to follow up on both for my Debian and PostgreSQL work. Next year's DebConf will take place in Santa Fe, Argentina. I haven't yet decided if I will be going, but I can recommend the experience to everyone! The post The Debian Conference 2025 in Brest appeared first on CYBERTEC PostgreSQL Services & Support.

28 July 2025

Dimitri John Ledkov: Achieving actually full disk encryption of UEFI ESP at rest with TCG OPAL, FIPS, LUKS

Achieving full disk encryption using FIPS, TCG OPAL and LUKS to encrypt UEFI ESP on bare-metal and in VMs
Many security standards such as CIS and STIG require to protect information at rest. For example, NIST SP 800-53r5 SC-28 advocate to use cryptographic protection, offline storage and TPMs to enhance protection of information confidentiality and/or integrity.Traditionally to satisfy such controls on portable devices such as laptops one would utilize software based Full Disk Encryption - Mac OS X FileVault, Windows Bitlocker, Linux cryptsetup LUKS2. In cases when FIPS cryptography is required, additional burden would be placed onto these systems to operate their kernels in FIPS mode.Trusted Computing Group works on establishing many industry standards and specifications, which are widely adopted to improve safety and security of computing whilst keeping it easy to use. One of their most famous specifications them is TCG TPM 2.0 (Trusted Platform Module). TPMs are now widely available on most devices and help to protect secret keys and attest systems. For example, most software full disk encryption solutions can utilise TCG TPM to store full disk encryption keys providing passwordless, biometric or pin-base ways to unlock the drives as well as attesting that system have not been modified or compromised whilst offline.TCG Storage Security Subsystem Class: Opal Specification is a set of specifications for features of data storage devices. The authors and contributors to OPAL are leading and well trusted storage manufacturers such as Samsung, Western Digital, Seagate Technologies, Dell, Google, Lenovo, IBM, Kioxia, among others. One of the features that Opal Specification enables is self-encrypting drives which becomes very powerful when combined with pre-boot authentication. Out of the box, such drives always and transparently encrypt all disk data using hardware acceleration. To protect data one can enter UEFI firmware setup (BIOS) to set NVMe single user password (or user + administrator/recovery passwords) to encrypt the disk encryption key. If one's firmware didn't come with such features, one can also use SEDutil to inspect and configure all of this. Latest release of major Linux distributions have SEDutil already packaged.Once password is set, on startup, pre-boot authentication will request one to enter password - prior to booting any operating systems. It means that full disk is actually encrypted, including the UEFI ESP and all operating systems that are installed in case of dual or multi-boot installations. This also prevents tampering with ESP, UEFI bootloaders and kernels which with traditional software-based encryption often remain unencrypted and accessible. It also means one doesn't have to do special OS level repartitioning, or installation steps to ensure all data is encrypted at rest.What about FIPS compliance? Well, the good news is that majority of the OPAL compliant hard drives and/or security sub-chips do have FIPS 140-3 certification. Meaning they have been tested by independent laboratories to ensure they do in-fact encrypt data. On the CMVP website one can search for module name terms "OPAL" or "NVMe" or name of hardware vendor to locate FIPS certificates.Are such drives widely available? Yes. For example, a common Thinkpad X1 gen 11 has OPAL NVMe drives as standard, and they have FIPS certification too. Thus, it is likely in your hardware fleet these are already widely available. Use sedutil to check if MediaEncrypt and LockingSupported features are available.Well, this is great for laptops and physical servers, but you may ask - what about public or private cloud? Actually, more or less the same is already in-place in both. On CVMP website all major clouds have their disk encryption hardware certified, and all of them always encrypt all Virtual Machines with FIPS certified cryptography without an ability to opt-out. One is however in full control of how the encryption keys are managed: cloud-provider or self-managed (either with a cloud HSM or KMS or bring your own / external). See these relevant encryption options and key management docs for GCP, Azure, AWS. But the key takeaway without doing anything, at rest, VMs in public cloud are always encrypted and satisfy NIST SP 800-53 controls.What about private cloud? Most Linux based private clouds ultimately use qemu typically with qcow2 virtual disk images. Qemu supports user-space encryption of qcow2 disk, see this manpage. Such encryption encrypts the full virtual machine disk, including the bootloader and ESP. And it is handled entirely outside of the VM on the host - meaning the VM never has access to the disk encryption keys. Qemu implements this encryption entirely in userspace using gnutls, nettle, libgcrypt depending on how it was compiled. This also means one can satisfy FIPS requirements entirely in userspace without a Linux kernel in FIPS mode. Higher level APIs built on top of qemu also support qcow2 disk encryption, as in projects such as libvirt and OpenStack Cinder.If you carefully read the docs, you may notice that agent support is explicitly sometimes called out as not supported or not mentioned. Quite often agents running inside the OS may not have enough observability to them to assess if there is external encryption. It does mean that monitoring above encryption options require different approaches - for example monitor your cloud configuration using tools such as Wiz and Orca, rather than using agents inside individual VMs. For laptop / endpoint security agents, I do wish they would start gaining capability to report OPAL SED availability and status if it is active or not.What about using software encryption none-the-less on top of the above solutions? It is commonly referred to double or multiple encryption. There will be an additional performance impact, but it can be worthwhile. It really depends on what you define as data at rest for yourself and which controls you need. If one has a dual-boot laptop, and wants to keep one OS encrypted whilst booted into the other, it can perfectly reasonable to encrypted the two using separate software encryption keys. In addition to the OPAL encryption of the ESP. For more targeted per-file / per-folder encryption, one can look into using gocryptfs which is the best successor to the once popular, but now deprecated eCryptfs (amazing tool, but has fallen behind in development and can lead to data loss).All of the above mostly talks about cryptographic encryption, which only provides confidentially but not data integrity. To protect integrity, one needs to choose how to maintain that. dm-verity is a good choice for read-only and rigid installations. For read-write workloads, it may be easier to deploy ZFS or Btrfs instead. If one is using filesystems without a built-in integrity support such as XFS or Ext4, one can retrofit integrity layer to them by using dm-integrity (either standalone, or via dm-luks/cryptsetup --integrity option).

If one has a lot of estate and a lot of encryption keys to keep track off a key management solution is likely needed. The most popular solution is likely the one from Thales Group marketed under ChiperTrust Data Security Platform (previously Vormetric), but there are many others including OEM / Vendor / Hardware / Cloud specific or agnostic solutions.

I hope this crash course guide piques your interest to learn and discover modern confidentially and integrity solutions, and to re-affirm or change your existing controls w.r.t. to data protection at rest.

Full disk encryption, including UEFI ESP /boot/efi is now widely achievable by default on both baremetal machines and in VMs including with FIPS certification. To discuss more let's connect on Linkedin.

Russ Allbery: Review: Cyteen

Review: Cyteen, by C.J. Cherryh
Series: Cyteen #1
Publisher: Warner Aspect
Copyright: 1988
Printing: September 1995
ISBN: 0-446-67127-4
Format: Trade paperback
Pages: 680
The main text below is an edited version of my original review of Cyteen written on 2012-01-03. Additional comments from my re-read are after the original review. I've reviewed several other C.J. Cherryh books somewhat negatively, which might give the impression I'm not a fan. That is an artifact of when I started reviewing. I first discovered Cherryh with Cyteen some 20 years ago, and it remains one of my favorite SF novels of all time. After finishing my reading for 2011, I was casting about for what to start next, saw Cyteen on my parents' shelves, and decided it was past time for my third reading, particularly given the recent release of a sequel, Regenesis. Cyteen is set in Cherryh's Alliance-Union universe following the Company Wars. It references several other books in that universe, most notably Forty Thousand in Gehenna but also Downbelow Station and others. It also has mentions of the Compact Space series (The Pride of Chanur and sequels). More generally, almost all of Cherryh's writing is loosely tied together by an overarching future history. One does not need to read any of those other books before reading Cyteen; this book will fill you in on all of the politics and history you need to know. I read Cyteen first and have never felt the lack. Cyteen was at one time split into three books for publishing reasons: The Betrayal, The Rebirth, and The Vindication. This is an awful way to think of the book. There are no internal pauses or reasonable volume breaks; Cyteen is a single coherent novel, and Cherryh has requested that it never be broken up that way again. If you happen to find all three portions as your reading copy, they contain all the same words and are serviceable if you remember it's a single novel under three covers, but I recommend against reading the portions in isolation. Human colonization of the galaxy started with slower-than-light travel sponsored by the private Sol Corporation. The inhabitants of the far-flung stations and the crews of the merchant ships that supplied them have formed their own separate cultures, but initially remained attached to Earth. That changed with the discovery of FTL travel and a botched attempt by Earth to reassert its authority. At the time of Cyteen, there are three human powers: distant Earth (which plays little role in this book), the merchanter Alliance, and Union. The planet Cyteen is one of only a few Earth-like worlds discovered by human expansion, and is the seat of government and the most powerful force in Union. This is primarily because of Reseune: the Cyteen lab that produces the azi. If Cyteen is about any one thing, it's about azi: genetically engineered human clones who are programmed via intensive psychological conditioning starting before birth. The conditioning uses a combination of drugs to make them receptive and "tape," specific patterns of instruction and sensory stimulation. They are designed for specific jobs or roles, they're conditioned to be obedient to regular humans, and they're not citizens. They are, in short, slaves. In a lot of books, that's as deep as the analysis would go. Azi are slaves, and slavery is certainly bad, so there would probably be a plot around azi overthrowing their conditioning, or around the protagonists trying to free them from servitude. But Cyteen is not any SF novel, and azi are considerably more complex and difficult than that analysis. We learn over the course of the book that the immensely powerful head of Reseune Labs, Ariane Emory, has a specific broader purpose in mind for the azi. One of the reasons why Reseune fought for and gained the role of legal protector of all azi in Union, regardless of where they were birthed, is so that Reseune could act to break any permanent dependence on azi as labor. And yet, they are slaves; one of the protagonists of Cyteen is an experimental azi, which makes him the permanent property of Reseune and puts him in constant jeopardy of being used as a political prisoner and lever of manipulation against those who care about him. Cyteen is a book about manipulation, about programming people, about what it means to have power over someone else's thoughts, and what one can do with that power. But it's also a book about connection and identity, about what makes up a personality, about what constitutes identity and how people construct the moral codes and values that they hold at their core. It's also a book about certainty. Azi are absolutely certain, and are capable of absolute trust, because that's part of their conditioning. Naturally-raised humans are not. This means humans can do things that azi can't, but the reverse is also true. The azi are not mindless slaves, nor are they mindlessly programmed, and several of the characters, both human and azi, find a lot of appeal in the core of certainty and deep self-knowledge of their own psychological rules that azis can have. Cyteen is a book about emotions, and logic, and where they come from and how to balance them. About whether emotional pain and uncertainty is beneficial or damaging, and about how one's experiences make up and alter one's identity. This is also a book about politics, both institutional and personal. It opens with Ariane Emory, Councilor for Science for five decades and the head of the ruling Union Expansionist party. She's powerful, brilliant, dangerously good at reading people, and dangerously willing to manipulate and control people for her own ends. What she wants, at the start of the book, is to completely clone a Special (the legal status given to the most brilliant minds of Union). This was attempted before and failed, but Ariane believes it's now possible, with a combination of tape, genetic engineering, and environmental control, to reproduce the brilliance of the original mind. To give Union another lifespan of work by their most brilliant thinkers. Jordan Warrick, another scientist at Reseune, has had a long-standing professional and personal feud with Ariane Emory. As the book opens, he is fighting to be transferred out from under her to the new research station that would be part of the Special cloning project, and he wants to bring his son Justin and Justin's companion azi Grant with them. Justin is a PR, a parental replicate, meaning he shares Jordan's genetic makeup but was not an attempt to reproduce the conditions of Jordan's rearing. Grant was raised as his brother. And both have, for reasons that are initially unclear, attracted the attention of Ariane, who may be using them as pawns. This is just the initial setup, and along with this should come a warning: the first 150 pages set up a very complex and dangerous political situation and build the tension that will carry the rest of the book, and they do this by, largely, torturing Justin and Grant. The viewpoint jumps around, but Justin and Grant are the primary protagonists for this first section of the book. While one feels sympathy for both of them, I have never, in my multiple readings of the book, particularly liked them. They're hard to like, as opposed to pity, during this setup; they have very little agency, are in way over their heads, are constantly making mistakes, and are essentially having their lives destroyed. Don't let this turn you off on the rest of the book. Cyteen takes a dramatic shift about 150 pages in. A new set of protagonists are introduced who are some of the most interesting, complex, and delightful protagonists in any SF novel I have read, and who are very much worth waiting for. While Justin has his moments later on (his life is so hard that his courage can be profoundly moving), it's not necessary to like him to love this book. That's one of the reasons why I so strongly dislike breaking it into three sections; that first section, which is mostly Justin and Grant, is not representative of the book. I can't talk too much more about the plot without risking spoiling it, but it's a beautiful, taut, and complex story that is full of my favorite things in both settings and protagonists. Cyteen is a book about brilliant people who think on their feet. Cherryh succeeds at showing this through what they do, which is rarely done as well as it is here. It's a book about remembering one's friends and remembering one's enemies, and waiting for the most effective moment to act, but it also achieves some remarkable transformations. About 150 pages in, you are likely to loathe almost everyone in Reseune; by the end of the book, you find yourself liking, or at least understanding, nearly everyone. This is extremely hard, and Cherryh pulls it off in most cases without even giving the people she's redeeming their own viewpoint sections. Other than perhaps George R.R. Martin I've not seen another author do this as well. And, more than anything else, Cyteen is a book with the most wonderful feeling of catharsis. I think this is one of the reasons why I adore this book and have difficulties with some of Cherryh's other works. She's always good at ramping up the tension and putting her characters in awful, untenable positions. Less frequently does she provide the emotional payoff of turning the tables, where you get to watch a protagonist do everything you've been wanting them to do for hundreds of pages, except even better and more delightfully than you would have come up with. Cyteen is one of the most emotionally satisfying books I've ever read. I could go on and on; there is just so much here that I love. Deep questions of ethics and self-control, presented in a way that one can see the consequences of both bad decisions and good ones and contrast them. Some of the best political negotiations in fiction. A wonderful look at friendship and loyalty from several directions. Two of the best semi-human protagonists I've seen, who one can see simultaneously as both wonderful friends and utterly non-human and who put nearly all of the androids in fiction to shame by being something trickier and more complex. A wonderful unfolding sense of power. A computer that can somewhat anticipate problems and somewhat can't, and that encapsulates much of what I love about semi-intelligent bases in science fiction. Cyteen has that rarest of properties of SF novels: Both the characters and the technology meld in a wonderful combination where neither could exist without the other, where the character issues are illuminated by the technology and the technology supports the characters. I have, for this book, two warnings. The first, as previously mentioned, is that the first 150 pages of setup is necessary but painful to read, and I never fully warmed to Justin and Grant throughout. I would not be surprised to hear that someone started this book but gave up on it after 50 or 100 pages. I do think it's worth sticking out the rocky beginning, though. Justin and Grant continue to be a little annoying, but there's so much other good stuff going on that it doesn't matter. The other warning is that part of the setup of the story involves the rape of an underage character. This is mostly off-camera, but the emotional consequences are significant (as they should be) and are frequently discussed throughout the book. There is also rather frank discussion of adolescent sexuality later in the book. I think both of these are relevant to the story and handled in a way that isn't gratuitous, but they made me uncomfortable and I don't have any past history with those topics. Those warnings notwithstanding, this is simply one of the best SF novels ever written. It uses technology to pose deep questions about human emotions, identity, and interactions, and it uses complex and interesting characters to take a close look at the impact of technology on lives. And it does this with a wonderfully taut, complicated plot that sustains its tension through all 680 pages, and with characters whom I absolutely love. I have no doubt that I'll be reading it for a fourth and fifth time some years down the road. Followed by Regenesis, although Cyteen stands well entirely on its own and there's no pressing need to read the sequel. Rating: 10 out of 10

Some additional thoughts after re-reading Cyteen in 2025: I touched on this briefly in my original review, but I was really struck during this re-read how much the azi are a commentary on and a complication of the role of androids in earlier science fiction. Asimov's Three Laws of Robotics were an attempt to control the risks of robots, but can also be read as turning robots into slaves. Azis make the slavery more explicit and disturbing by running the programming on a human biological platform, but they're more explicitly programmed and artificial than a lot of science fiction androids. Artificial beings and their relationship to humans have been a recurring theme of SF since Frankenstein, but I can't remember a novel that makes the comparison to humans this ambiguous and conflicted. The azi not only like being azi, they can describe why they prefer it. It's clear that Union made azi for many of the same reasons that humans enslave other humans, and that Ariane Emory is using them as machinery in a larger (and highly ethically questionable) plan, but Cherryh gets deeper into the emergent social complications and societal impact than most SF novels manage. Azi are apparently closer to humans than the famous SF examples such as Commander Data, but the deep differences are both more subtle and more profound. I've seen some reviewers who are disturbed by the lack of a clear moral stance by the protagonists against the creation of azi. I'm not sure what to think about that. It's clear the characters mostly like the society they've created, and the groups attempting to "free" azi from their "captivity" are portrayed as idiots who have no understanding of azi psychology. Emory says she doesn't want azi to be a permanent aspect of society but clearly has no intention of ending production any time soon. The book does seem oddly unaware that the production of azi is unethical per se and, unlike androids, has an obvious exit ramp: Continue cloning gene lines as needed to maintain a sufficient population for a growing industrial civilization, but raise the children as children rather than using azi programming. If Cherryh included some reason why that was infeasible, I didn't see it, and I don't think the characters directly confronted it. I don't think societies in books need to be ethical, or that Cherryh intended to defend this one. There are a lot of nasty moral traps that civilizations can fall into that make for interesting stories. But the lack of acknowledgment of the problem within the novel did seem odd this time around. The other part of this novel that was harder to read past in this re-read is the sexual ethics. There's a lot of adolescent sexuality in this book, and even apart from the rape scene which was more on-the-page than I had remembered and which is quite (intentionally) disturbing there is a whole lot of somewhat dubious consent. Maybe I've gotten older or just more discriminating, but it felt weirdly voyeuristic to know this much about the sex lives of characters who are, at several critical points in the story, just a bunch of kids. All that being said, and with the repeated warning that the first 150 pages of this novel are just not very good, there is still something magic about the last two-thirds of this book. It has competence porn featuring a precociously brilliant teenager who I really like, it has one of the more interesting non-AI programmed computer systems that I've read in SF, it has satisfying politics that feel like modern politics (media strategy and relationships and negotiated alliances, rather than brute force and ideology), and it has a truly excellent feeling of catharsis. The plot resolution is a bit too abrupt and a bit insufficiently explained (there's more in Regenesis), but even though this was my fourth time through this book, the pacing grabbed me again and I could barely put down the last part of the story. Ethics aside (and I realize that's quite the way to start a sentence), I find the azi stuff fascinating. I know the psychology in this book is not real and is hopelessly simplified compared to real psychology, but there's something in the discussions of value sets and flux and self-knowledge that grabs my interest and makes me want to ponder. I think it's the illusion of simplicity and control, the what-if premise of thought where core motivations and moral rules could be knowable instead of endlessly fluid the way they are in us humans. Cherryh's azi are some of the most intriguing androids in science fiction to me precisely because they don't start with computers and add the humanity in, but instead start with humanity and overlay a computer-like certainty of purpose that's fully self-aware. The result is more subtle and interesting than anything Star Trek managed. I was not quite as enamored with this book this time around, but it's still excellent once the story gets properly started. I still would recommend it, but I might add more warnings about the disturbing parts.

Re-read rating: 9 out of 10

27 July 2025

Russ Allbery: Review: The Dragon's Banker

Review: The Dragon's Banker, by Scott Warren
Publisher: Scott Warren
Copyright: September 2019
ISBN: 0-578-55292-2
Format: Kindle
Pages: 263
The Dragon's Banker is a self-published stand-alone fantasy novel, set in a secondary world with roughly Renaissance levels of technology and primarily alchemical magic. The version I read includes an unrelated novelette, "Forego Quest." I have the vague impression that this novel shares a world with other fantasy novels by the same author, but I have not read them and never felt like I was missing something important. Sailor Kelstern is a merchant banker. He earns his livelihood by financing caravans and sea voyages and taking a cut of the profits. He is not part of the primary banking houses of the city; instead, he has a small, personal business with a loyal staff that looks for opportunities the larger houses may have overlooked. As the story opens, he has fallen on hard times due in part to a spectacular falling-out with a previous client and is in desperate need of new opportunities. The jewel-bedecked Lady Arkelai and her quest for private banking services for her father, Lord Alkazarian, may be exactly what he needs. Or it may be a dangerous trap; Sailor has had disastrous past experience with nobles attempting to strong-arm him into their service. Unbeknownst to Sailor, Lord Alkazarian is even more dangerous than he first appears. He is sitting on a vast hoard of traditional riches whose value is endangered by the rise of new-fangled paper money. He is not at all happy about this development. He is also a dragon. I, and probably many other people who read this book, picked it up because it was recommended by Matt Levine as a fantasy about finance instead of the normal magical adventuring. I knew it was self-published going in, so I wasn't expecting polished writing. My hope was for interesting finance problems in a fantasy context, similar to the kind of things Matt Levine's newsletter is about: schemes for financing risky voyages, complications around competing ideas of money, macroeconomic risks from dragon hoards, complex derivatives, principal-agent problems, or something similar that goes beyond the (annoyingly superficial) treatment of finance in most fantasy novels. Unfortunately, what I got was a rather standard fantasy setting and a plot that revolves mostly around creative uses for magical devices, some conventional political skulduggery, and a lot of energetic but rather superficial business hustling. The protagonist is indeed a merchant banker who is in no way a conventional fantasy hero (one of the most taxing parts of Sailor's occasional visits to the dragon is the long hike down to the hoard, or rather the long climb back out), but the most complex financial instrument that appears in this book is straightforward short-selling. Alas. I was looking forward to the book that I hoped this was. Given my expectations, this was a disappointment. I kept waiting for the finances to get more complicated and interesting, and that kept not happening. Without that expectation, this is... okay, I guess. The writing is adequate but kind of stilted, presumably in an effort to make it sound slightly archaic, and has a strong self-published feel. Sailor is not a bad protagonist, but neither is he all that memorable. I did like some of the world-building, which has an attention to creative uses of bits of magic that readers who like gadget fantasy may appreciate. There are a lot of plot conveniences and coincidences, though, and very little of this is going to feel original to a long-time fantasy reader. Putting some of the complexity of real Renaissance banking and finance systems into a fantasy world is a great idea, but I've yet to read one that lived up to the potential of the premise. (Neal Stephenson's Baroque Cycle comes the closest; unfortunately, the non-economic parts of that over-long series are full of Stephenson's worst writing habits.) Part of the problem is doubtless that I am reasonably well-read in economics, so my standards are high. Maybe the average reader would be content with a few bits on the perils of investment, a simple treatment of trust in currency, and a mention or two of short-selling, which is what you get in this book. I am not altogether sorry that I read this, but I wouldn't recommend it. I encourage Matt Levine to read more genre fiction and find some novels with more interesting financial problems! "Forego Quest": This included novelette, on the other hand, was surprisingly good and raised my overall rating for the book by a full point. Arturus Kingson is the Chosen One. He is not the Chosen One of a single prophecy or set of prophecies; no, he's the Chosen One of, apparently, all of them, no matter how contradictory, and he wants absolutely nothing to do with any of them. Magical swords litter his path. He has so many scars and birthmarks that they look like a skin condition. Beautiful women approach him in bars. Mysterious cloaked strangers die dramatically in front of him. Owls try to get into his bedroom window. It's all very exhausting, since the universe absolutely refuses to take no for an answer. There isn't much more to the story than this, but Warren writes it in the first person with just the right tone of exasperated annoyance and gives Arturus a real problem to solve and enough of a plot to provide some structure. I'm usually not a fan of parody stories because too many of them feel like juvenile slapstick. This one is sarcastic instead, which is much more to my taste. "Forego Quest" goes on perhaps a bit too long, and the ending was not as successful as the rest of the book, but this was a lot of fun and made me laugh. (7) Rating: 6 out of 10

26 July 2025

Bits from Debian: DebConf25 closes in Brest and DebConf26 announced

DebConf25 group photo - click to enlarge On Saturday 19 July 2025, the annual Debian Developers and Contributors Conference came to a close. Over 443 attendees representing 50 countries from around the world came together for a combined 169 events (including some which took place during the DebCamp) including more than 50 Talks, 39 Short Talks, 5 Discussions, 59 Birds of a Feather sessions ("BoF" informal meeting between developers and users), 10 workshops, and activities in support of furthering our distribution and free software, 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 7 through 13 July 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, a session was dedicated to prepare the BoF "Dealing with Dormant Packages: Ensuring Debian's High Standards"; another, at the initiative of our DPL, to prepare suggestions for the BoF Package Acceptance in Debian: Challenges and Opportunities"; and an afternoon around Salsa-CI. As has been the case for several years, a special effort has been made to welcome newcomers and help them become familiar with Debian and DebConf by organizing a sprint "New Contributors Onboarding" every day of Debcamp, followed more informally by mentorship during DebConf. The actual Debian Developers Conference started on Monday 14 July 2025. In addition to the traditional "Bits from the DPL" talk, the continuous key-signing party, lightning talks, and the announcement of next year's DebConf26, 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", the "What's New in the Linux Kernel" session, and a set of BoFs about Debian packaging policy and Debian infrastructure. Thus, more than a quarter of the discussions dealt with this theme, including talks about our tools and Debian's archive processes. Internationalization and Localization have been the subject of several talks. The Python, Perl, Ruby, Go, and Rust programming language teams also shared updates on their work and efforts. Several talks have covered Debian Blends and Debian-derived distributions and other talks addressed the issue of Debian and AI. More than 17 BoFs and talks about community, diversity, and local outreach highlighted the work of various teams involved in not just the technical but also the social aspect of our community; four women who have made contributions to Debian through their artwork in recent years presented their work. The one-day session "DebConf 2025 Academic Track!", organized in collaboration with the IRISA laboratory was the first session welcoming fellow academics at DebConf, bringing together around ten presentations. 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 (this year with cider as well), the Group Photos, and the Day Trips. For those who were not able to attend, most of the talks and sessions were broadcasted live and recorded; currently the videos are made available through this link. Almost all of the sessions facilitated remote participation via IRC and Matrix 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. DebConf25 saw over 441 T-shirts, 3 day trips, and up to 315 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 Brest, France and online around the world. The DebConf25 website will remain active for archival purposes and will continue to offer links to the presentations and videos of talks and events. Next year, DebConf26 will be held in Santa Fe, Argentina, likely in July. As tradition follows before the next DebConf the local organizers in Argentina will start the conference activities with DebCamp with a 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 on the DebConf25 website for more details on this. Debian thanks the commitment of numerous sponsors to support DebConf25, particularly our Platinum Sponsors: AMD, EDF, Infomaniak, Proxmox, and Viridien. We also wish to thank our Video and Infrastructure teams, the DebConf25 and DebConf committees, our host nation of France, 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, Bosnia and Herzegovina, India, Korea. More information about DebConf is available from https://debconf.org/. About AMD The AMD ROCm platform includes programming models, tools, compilers, libraries, and runtimes for AI and HPC solution development on AMD GPUs. Debian is an officially supported platform for AMD ROCm and a growing number of components are now included directly in the Debian distribution. For more than 55 years AMD has driven innovation in high-performance computing, graphics and visualization technologies. AMD is deeply committed to supporting and contributing to open-source projects, foundations, and open-standards organizations, taking pride in fostering innovation and collaboration within the open-source community. About EDF EDF is a leading global utility company focused on low-carbon power generation. The group uses advanced engineering and scientific computing tools to drive innovation and efficiency in its operations, especially in nuclear power plant design and safety assessment. Since 2003, the EDF Group has been using Debian as its main scientific computing environment. Debian's focus on stability and reproducibility ensures that EDF's calculations and simulations produce consistent and accurate results. About Infomaniak Infomaniak is Switzerland's leading developer of Web technologies. With operations all over Europe and based exclusively in Switzerland, the company designs and manages its own data centers powered by 100% renewable energy, and develops all its solutions locally, without outsourcing. With millions of users and the trust of public and private organizations across Europe - such as RTBF, the United Nations, central banks, over 3,000 radio and TV stations, as well as numerous cities and security bodies - Infomaniak stands for sovereign, sustainable and independent digital technology. The company offers a complete suite of collaborative tools, cloud hosting, streaming, marketing and events solutions, while being owned by its employees and self-financed exclusively by its customers. About Proxmox Proxmox develops powerful, yet easy-to-use Open Source server software. The product portfolio from Proxmox, including server virtualization, backup, and email security, helps companies of any size, sector, or industry to simplify their IT infrastructures. The Proxmox solutions are built on Debian, we are happy that they give back to the community by sponsoring DebConf25. About Viridien Viridien is an advanced technology, digital and Earth data company that pushes the boundaries of science for a more prosperous and sustainable future. Viridien has been using Debian-based systems to power most of its HPC infrastructure and its cloud platform since 2009 and currently employs two active Debian Project Members. Contact Information For further information, please visit the DebConf25 web page at https://debconf25.debconf.org/ or send mail to press@debian.org.

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