Search Results: "ecki"

28 February 2024

Dirk Eddelbuettel: RcppEigen on CRAN: New Upstream, At Last

We are thrilled to share that RcppEigen has now upgraded to Eigen release 3.4.0! The new release arrived on CRAN earlier today, and has been shipped to Debian as well. Eigen is a C++ template library for linear algebra: matrices, vectors, numerical solvers, and related algorithms. This update has been in the works for a full two and a half years! It all started with a PR #102 by Yixuan bringing the package-local changes for R integration forward to usptream release 3.4.0. We opened issue #103 to steer possible changes from reverse-dependency checking through. Lo and behold, this just stalled because a few substantial changes were needed and not coming. But after a long wait, and like a bolt out of a perfectly blue sky, Andrew revived it in January with a reverse depends run of his own along with a set of PRs. That was the push that was needed, and I steered it along with a number of reverse dependency checks, and occassional emails to maintainers. We managed to bring it down to only three packages having a hickup, and all three had received PRs thanks to Andrew and even merged them. So the plan became to release today following a final fourteen day window. And CRAN was convinced by our arguments that we followed due process. So there it is! Big big thanks to all who helped it along, especially Yixuan and Andrew but also Mikael who updated another patch set he had prepared for the previous release series. The complete NEWS file entry follows.

Changes in RcppEigen version (2024-02-28)
  • The Eigen version has been upgrade to release 3.4.0 (Yixuan)
  • Extensive reverse-dependency checks ensure only three out of over 400 packages at CRAN are affected; PRs and patches helped other packages
  • The long-running branch also contains substantial contributions from Mikael Jagan (for the lme4 interface) and Andrew Johnson (revdep PRs)

Courtesy of CRANberries, there is also a diffstat report for the most recent release. If you like this or other open-source work I do, you can sponsor me at GitHub.

This post by Dirk Eddelbuettel originated on his Thinking inside the box blog. Please report excessive re-aggregation in third-party for-profit settings.

24 February 2024

Niels Thykier: Language Server for Debian: Spellchecking

This is my third update on writing a language server for Debian packaging files, which aims at providing a better developer experience for Debian packagers. Lets go over what have done since the last report.
Semantic token support I have added support for what the Language Server Protocol (LSP) call semantic tokens. These are used to provide the editor insights into tokens of interest for users. Allegedly, this is what editors would use for syntax highlighting as well. Unfortunately, eglot (emacs) does not support semantic tokens, so I was not able to test this. There is a 3-year old PR for supporting with the last update being ~3 month basically saying "Please sign the Copyright Assignment". I pinged the GitHub issue in the hopes it will get unstuck. For good measure, I also checked if I could try it via neovim. Before installing, I read the neovim docs, which helpfully listed the features supported. Sadly, I did not spot semantic tokens among those and parked from there. That was a bit of a bummer, but I left the feature in for now. If you have an LSP capable editor that supports semantic tokens, let me know how it works for you! :)
Spellchecking Finally, I implemented something Otto was missing! :) This stared with Paul Wise reminding me that there were Python binding for the hunspell spellchecker. This enabled me to get started with a quick prototype that spellchecked the Description fields in debian/control. I also added spellchecking of comments while I was add it. The spellchecker runs with the standard en_US dictionary from hunspell-en-us, which does not have a lot of technical terms in it. Much less any of the Debian specific slang. I spend considerable time providing a "built-in" wordlist for technical and Debian specific slang to overcome this. I also made a "wordlist" for known Debian people that the spellchecker did not recognise. Said wordlist is fairly short as a proof of concept, and I fully expect it to be community maintained if the language server becomes a success. My second problem was performance. As I had suspected that spellchecking was not the fastest thing in the world. Therefore, I added a very small language server for the debian/changelog, which only supports spellchecking the textual part. Even for a small changelog of a 1000 lines, the spellchecking takes about 5 seconds, which confirmed my suspicion. With every change you do, the existing diagnostics hangs around for 5 seconds before being updated. Notably, in emacs, it seems that diagnostics gets translated into an absolute character offset, so all diagnostics after the change gets misplaced for every character you type. Now, there is little I could do to speed up hunspell. But I can, as always, cheat. The way diagnostics work in the LSP is that the server listens to a set of notifications like "document opened" or "document changed". In a response to that, the LSP can start its diagnostics scanning of the document and eventually publish all the diagnostics to the editor. The spec is quite clear that the server owns the diagnostics and the diagnostics are sent as a "notification" (that is, fire-and-forgot). Accordingly, there is nothing that prevents the server from publishing diagnostics multiple times for a single trigger. The only requirement is that the server publishes the accumulated diagnostics in every publish (that is, no delta updating). Leveraging this, I had the language server for debian/changelog scan the document and publish once for approximately every 25 typos (diagnostics) spotted. This means you quickly get your first result and that clears the obsolete diagnostics. Thereafter, you get frequent updates to the remainder of the document if you do not perform any further changes. That is, up to a predefined max of typos, so we do not overload the client for longer changelogs. If you do any changes, it resets and starts over. The only bit missing was dealing with concurrency. By default, a pygls language server is single threaded. It is not great if the language server hangs for 5 seconds everytime you type anything. Fortunately, pygls has builtin support for asyncio and threaded handlers. For now, I did an async handler that await after each line and setup some manual detection to stop an obsolete diagnostics run. This means the server will fairly quickly abandon an obsolete run. Also, as a side-effect of working on the spellchecking, I fixed multiple typos in the changelog of debputy. :)
Follow up on the "What next?" from my previous update In my previous update, I mentioned I had to finish up my python-debian changes to support getting the location of a token in a deb822 file. That was done, the MR is now filed, and is pending review. Hopefully, it will be merged and uploaded soon. :) I also submitted my proposal for a different way of handling relationship substvars to debian-devel. So far, it seems to have received only positive feedback. I hope it stays that way and we will have this feature soon. Guillem proposed to move some of this into dpkg, which might delay my plans a bit. However, it might be for the better in the long run, so I will wait a bit to see what happens on that front. :) As noted above, I managed to add debian/changelog as a support format for the language server. Even if it only does spellchecking and trimming of trailing newlines on save, it technically is a new format and therefore cross that item off my list. :D Unfortunately, I did not manage to write a linter variant that does not involve using an LSP-capable editor. So that is still pending. Instead, I submitted an MR against elpa-dpkg-dev-el to have it recognize all the fields that the debian/control LSP knows about at this time to offset the lack of semantic token support in eglot.
From here... My sprinting on this topic will soon come to an end, so I have to a bit more careful now with what tasks I open! I think I will narrow my focus to providing a batch linting interface. Ideally, with an auto-fix for some of the more mechanical issues, where this is little doubt about the answer. Additionally, I think the spellchecking will need a bit more maturing. My current code still trips on naming patterns that are "clearly" verbatim or code references like things written in CamelCase or SCREAMING_SNAKE_CASE. That gets annoying really quickly. It also trips on a lot of commands like dpkg-gencontrol, but that is harder to fix since it could have been a real word. I think those will have to be fixed people using quotes around the commands. Maybe the most popular ones will end up in the wordlist. Beyond that, I will play it by ear if I have any time left. :)

21 February 2024

Niels Thykier: Expanding on the Language Server (LSP) support for debian/control

I have spent some more time on improving my language server for debian/control. Today, I managed to provide the following features:
  • The X- style prefixes for field names are now understood and handled. This means the language server now considers XC-Package-Type the same as Package-Type.

  • More diagnostics:

    • Fields without values now trigger an error marker
    • Duplicated fields now trigger an error marker
    • Fields used in the wrong paragraph now trigger an error marker
    • Typos in field names or values now trigger a warning marker. For field names, X- style prefixes are stripped before typo detection is done.
    • The value of the Section field is now validated against a dataset of known sections and trigger a warning marker if not known.
  • The "on-save trim end of line whitespace" now works. I had a logic bug in the server side code that made it submit "no change" edits to the editor.

  • The language server now provides "hover" documentation for field names. There is a small screenshot of this below. Sadly, emacs does not support markdown or, if it does, it does not announce the support for markdown. For now, all the documentation is always in markdown format and the language server will tag it as either markdown or plaintext depending on the announced support.

  • The language server now provides quick fixes for some of the more trivial problems such as deprecated fields or typos of fields and values.

  • Added more known fields including the XS-Autobuild field for non-free packages along with a link to the relevant devref section in its hover doc.

This covers basically all my known omissions from last update except spellchecking of the Description field. An image of emacs showing documentation for the Provides field from the language server.
Spellchecking Personally, I feel spellchecking would be a very welcome addition to the current feature set. However, reviewing my options, it seems that most of the spellchecking python libraries out there are not packaged for Debian, or at least not other the name I assumed they would be. The alternative is to pipe the spellchecking to another program like aspell list. I did not test this fully, but aspell list does seem to do some input buffering that I cannot easily default (at least not in the shell). Though, either way, the logic for this will not be trivial and aspell list does not seem to include the corrections either. So best case, you would get typo markers but no suggestions for what you should have typed. Not ideal. Additionally, I am also concerned with the performance for this feature. For d/control, it will be a trivial matter in practice. However, I would be reusing this for d/changelog which is 99% free text with plenty of room for typos. For a regular linter, some slowness is acceptable as it is basically a batch tool. However, for a language server, this potentially translates into latency for your edits and that gets annoying. While it is definitely on my long term todo list, I am a bit afraid that it can easily become a time sink. Admittedly, this does annoy me, because I wanted to cross off at least one of Otto's requested features soon.
On wrap-and-sort support The other obvious request from Otto would be to automate wrap-and-sort formatting. Here, the problem is that "we" in Debian do not agree on the one true formatting of debian/control. In fact, I am fairly certain we do not even agree on whether we should all use wrap-and-sort. This implies we need a style configuration. However, if we have a style configuration per person, then you get style "ping-pong" for packages where the co-maintainers do not all have the same style configuration. Additionally, it is very likely that you are a member of multiple packaging teams or groups that all have their own unique style. Ergo, only having a personal config file is doomed to fail. The only "sane" option here that I can think of is to have or support "per package" style configuration. Something that would be committed to git, so the tooling would automatically pick up the configuration. Obviously, that is not fun for large packaging teams where you have to maintain one file per package if you want a consistent style across all packages. But it beats "style ping-pong" any day of the week. Note that I am perfectly open to having a personal configuration file as a fallback for when the "per package" configuration file is absent. The second problem is the question of which format to use and what to name this file. Since file formats and naming has never been controversial at all, this will obviously be the easy part of this problem. But the file should be parsable by both wrap-and-sort and the language server, so you get the same result regardless of which tool you use. If we do not ensure this, then we still have the style ping-pong problem as people use different tools. This also seems like time sink with no end. So, what next then...?
What next? On the language server front, I will have a look at its support for providing semantic hints to the editors that might be used for syntax highlighting. While I think most common Debian editors have built syntax highlighting already, I would like this language server to stand on its own. I would like us to be in a situation where we do not have implement yet another editor extension for Debian packaging files. At least not for editors that support the LSP spec. On a different front, I have an idea for how we go about relationship related substvars. It is not directly related to this language server, except I got triggered by the language server "missing" a diagnostic for reminding people to add the magic Depends: $ misc:Depends [, $ shlibs:Depends ] boilerplate. The magic boilerplate that you have to write even though we really should just fix this at a tooling level instead. Energy permitting, I will formulate a proposal for that and send it to debian-devel. Beyond that, I think I might start adding support for another file. I also need to wrap up my python-debian branch, so I can get the position support into the Debian soon, which would remove one papercut for using this language server. Finally, it might be interesting to see if I can extract a "batch-linter" version of the diagnostics and related quickfix features. If nothing else, the "linter" variant would enable many of you to get a "mini-Lintian" without having to do a package build first.

20 February 2024

Niels Thykier: Language Server (LSP) support for debian/control

About a month ago, Otto Kek l inen asked for editor extensions for debian related files on the debian-devel mailing list. In that thread, I concluded that what we were missing was a "Language Server" (LSP) for our packaging files. Last week, I started a prototype for such a LSP for the debian/control file as a starting point based on the pygls library. The initial prototype worked and I could do very basic diagnostics plus completion suggestion for field names.
Current features I got 4 basic features implemented, though I have only been able to test two of them in emacs.
  • Diagnostics or linting of basic issues.
  • Completion suggestions for all known field names that I could think of and values for some fields.
  • Folding ranges (untested). This feature enables the editor to "fold" multiple lines. It is often used with multi-line comments and that is the feature currently supported.
  • On save, trim trailing whitespace at the end of lines (untested). Might not be registered correctly on the server end.
Despite its very limited feature set, I feel editing debian/control in emacs is now a much more pleasant experience. Coming back to the features that Otto requested, the above covers a grand total of zero. Sorry, Otto. It is not you, it is me.
Completion suggestions For completion, all known fields are completed. Place the cursor at the start of the line or in a partially written out field name and trigger the completion in your editor. In my case, I can type R-R-R and trigger the completion and the editor will automatically replace it with Rules-Requires-Root as the only applicable match. Your milage may vary since I delegate most of the filtering to the editor, meaning the editor has the final say about whether your input matches anything. The only filtering done on the server side is that the server prunes out fields already used in the paragraph, so you are not presented with the option to repeat an already used field, which would be an error. Admittedly, not an error the language server detects at the moment, but other tools will. When completing field, if the field only has one non-default value such as Essential which can be either no (the default, but you should not use it) or yes, then the completion suggestion will complete the field along with its value. This is mostly only applicable for "yes/no" fields such as Essential and Protected. But it does also trigger for Package-Type at the moment. As for completing values, here the language server can complete the value for simple fields such as "yes/no" fields, Multi-Arch, Package-Type and Priority. I intend to add support for Section as well - maybe also Architecture.
Diagnostics On the diagnostic front, I have added multiple diagnostics:
  • An error marker for syntax errors.
  • An error marker for missing a mandatory field like Package or Architecture. This also includes Standards-Version, which is admittedly mandatory by policy rather than tooling falling part.
  • An error marker for adding Multi-Arch: same to an Architecture: all package.
  • Error marker for providing an unknown value to a field with a set of known values. As an example, writing foo in Multi-Arch would trigger this one.
  • Warning marker for using deprecated fields such as DM-Upload-Allowed, or when setting a field to its default value for fields like Essential. The latter rule only applies to selected fields and notably Multi-Arch: no does not trigger a warning.
  • Info level marker if a field like Priority duplicates the value of the Source paragraph.
Notable omission at this time:
  • No errors are raised if a field does not have a value.
  • No errors are raised if a field is duplicated inside a paragraph.
  • No errors are used if a field is used in the wrong paragraph.
  • No spellchecking of the Description field.
  • No understanding that Foo and X[CBS]-Foo are related. As an example, XC-Package-Type is completely ignored despite being the old name for Package-Type.
  • Quick fixes to solve these problems... :)
Trying it out If you want to try, it is sadly a bit more involved due to things not being uploaded or merged yet. Also, be advised that I will regularly rebase my git branches as I revise the code. The setup:
  • Build and install the deb of the main branch of pygls from The package is in NEW and hopefully this step will soon just be a regular apt install.
  • Build and install the deb of the rts-locatable branch of my python-debian fork from There is a draft MR of it as well on the main repo.
  • Build and install the deb of the lsp-support branch of debputy from
  • Configure your editor to run debputy lsp debian/control as the language server for debian/control. This is depends on your editor. I figured out how to do it for emacs (see below). I also found a guide for neovim at Note that debputy can be run from any directory here. The debian/control is a reference to the file format and not a concrete file in this case.
Obviously, the setup should get easier over time. The first three bullet points should eventually get resolved by merges and upload meaning you end up with an apt install command instead of them. For the editor part, I would obviously love it if we can add snippets for editors to make the automatically pick up the language server when the relevant file is installed.
Using the debputy LSP in emacs The guide I found so far relies on eglot. The guide below assumes you have the elpa-dpkg-dev-el package installed for the debian-control-mode. Though it should be a trivially matter to replace debian-control-mode with a different mode if you use a different mode for your debian/control file. In your emacs init file (such as ~/.emacs or ~/.emacs.d/init.el), you add the follow blob.
(with-eval-after-load 'eglot
    (add-to-list 'eglot-server-programs
        '(debian-control-mode . ("debputy" "lsp" "debian/control"))))
Once you open the debian/control file in emacs, you can type M-x eglot to activate the language server. Not sure why that manual step is needed and if someone knows how to automate it such that eglot activates automatically on opening debian/control, please let me know. For testing completions, I often have to manually activate them (with C-M-i or M-x complete-symbol). Though, it is a bit unclear to me whether this is an emacs setting that I have not toggled or something I need to do on the language server side.
From here As next steps, I will probably look into fixing some of the "known missing" items under diagnostics. The quick fix would be a considerable improvement to assisting users. In the not so distant future, I will probably start to look at supporting other files such as debian/changelog or look into supporting configuration, so I can cover formatting features like wrap-and-sort. I am also very much open to how we can provide integrations for this feature into editors by default. I will probably create a separate binary package for specifically this feature that pulls all relevant dependencies that would be able to provide editor integrations as well.

Niels Thykier: Language Server (LSP) support for debian/control

Work done:
  • [X] No errors are raised if a field does not have a value.
  • [X] No errors are raised if a field is duplicated inside a paragraph.
  • [X] No errors are used if a field is used in the wrong paragraph.
  • [ ] No spellchecking of the Description field.
  • [X] No understanding that Foo and X[CBS]-Foo are related. As an example, XC-Package-Type is completely ignored despite being the old name for Package-Type.
  • [X] Fixed the on-save trim end of line whitespace. Bug in the server end.
  • [X] Hover text for field names

7 February 2024

Reproducible Builds: Reproducible Builds in January 2024

Welcome to the January 2024 report from the Reproducible Builds project. In these reports we outline the most important things that we have been up to over the past month. If you are interested in contributing to the project, please visit our Contribute page on our website.

How we executed a critical supply chain attack on PyTorch John Stawinski and Adnan Khan published a lengthy blog post detailing how they executed a supply-chain attack against PyTorch, a popular machine learning platform used by titans like Google, Meta, Boeing, and Lockheed Martin :
Our exploit path resulted in the ability to upload malicious PyTorch releases to GitHub, upload releases to [Amazon Web Services], potentially add code to the main repository branch, backdoor PyTorch dependencies the list goes on. In short, it was bad. Quite bad.
The attack pivoted on PyTorch s use of self-hosted runners as well as submitting a pull request to address a trivial typo in the project s README file to gain access to repository secrets and API keys that could subsequently be used for malicious purposes.

New Arch Linux forensic filesystem tool On our mailing list this month, long-time Reproducible Builds developer kpcyrd announced a new tool designed to forensically analyse Arch Linux filesystem images. Called archlinux-userland-fs-cmp, the tool is supposed to be used from a rescue image (any Linux) with an Arch install mounted to, [for example], /mnt. Crucially, however, at no point is any file from the mounted filesystem eval d or otherwise executed. Parsers are written in a memory safe language. More information about the tool can be found on their announcement message, as well as on the tool s homepage. A GIF of the tool in action is also available.

Issues with our SOURCE_DATE_EPOCH code? Chris Lamb started a thread on our mailing list summarising some potential problems with the source code snippet the Reproducible Builds project has been using to parse the SOURCE_DATE_EPOCH environment variable:
I m not 100% sure who originally wrote this code, but it was probably sometime in the ~2015 era, and it must be in a huge number of codebases by now. Anyway, Alejandro Colomar was working on the shadow security tool and pinged me regarding some potential issues with the code. You can see this conversation here.
Chris ends his message with a request that those with intimate or low-level knowledge of time_t, C types, overflows and the various parsing libraries in the C standard library (etc.) contribute with further info.

Distribution updates In Debian this month, Roland Clobus posted another detailed update of the status of reproducible ISO images on our mailing list. In particular, Roland helpfully summarised that all major desktops build reproducibly with bullseye, bookworm, trixie and sid provided they are built for a second time within the same DAK run (i.e. [within] 6 hours) . Additionally 7 of the 8 bookworm images from the official download link build reproducibly at any later time. In addition to this, three reviews of Debian packages were added, 17 were updated and 15 were removed this month adding to our knowledge about identified issues. Elsewhere, Bernhard posted another monthly update for his work elsewhere in openSUSE.

Community updates There were made a number of improvements to our website, including Bernhard M. Wiedemann fixing a number of typos of the term nondeterministic . [ ] and Jan Zerebecki adding a substantial and highly welcome section to our page about SOURCE_DATE_EPOCH to document its interaction with distribution rebuilds. [ ].
diffoscope is our in-depth and content-aware diff utility that can locate and diagnose reproducibility issues. This month, Chris Lamb made a number of changes such as uploading versions 245 and 255 to Debian but focusing on triaging and/or merging code from other contributors. This included adding support for comparing eXtensible ARchive (.XAR/.PKG) files courtesy of Seth Michael Larson [ ][ ], as well considerable work from Vekhir in order to fix compatibility between various and subtle incompatible versions of the progressbar libraries in Python [ ][ ][ ][ ]. Thanks!

Reproducibility testing framework The Reproducible Builds project operates a comprehensive testing framework (available at in order to check packages and other artifacts for reproducibility. In January, a number of changes were made by Holger Levsen:
  • Debian-related changes:
    • Reduce the number of arm64 architecture workers from 24 to 16. [ ]
    • Use diffoscope from the Debian release being tested again. [ ]
    • Improve the handling when killing unwanted processes [ ][ ][ ] and be more verbose about it, too [ ].
    • Don t mark a job as failed if process marked as to-be-killed is already gone. [ ]
    • Display the architecture of builds that have been running for more than 48 hours. [ ]
    • Reboot arm64 nodes when they hit an OOM (out of memory) state. [ ]
  • Package rescheduling changes:
    • Reduce IRC notifications to 1 when rescheduling due to package status changes. [ ]
    • Correctly set SUDO_USER when rescheduling packages. [ ]
    • Automatically reschedule packages regressing to FTBFS (build failure) or FTBR (build success, but unreproducible). [ ]
  • OpenWrt-related changes:
    • Install the python3-dev and python3-pyelftools packages as they are now needed for the sunxi target. [ ][ ]
    • Also install the libpam0g-dev which is needed by some OpenWrt hardware targets. [ ]
  • Misc:
    • As it s January, set the real_year variable to 2024 [ ] and bump various copyright years as well [ ].
    • Fix a large (!) number of spelling mistakes in various scripts. [ ][ ][ ]
    • Prevent Squid and Systemd processes from being killed by the kernel s OOM killer. [ ]
    • Install the iptables tool everywhere, else our custom rc.local script fails. [ ]
    • Cleanup the /srv/workspace/pbuilder directory on boot. [ ]
    • Automatically restart Squid if it fails. [ ]
    • Limit the execution of chroot-installation jobs to a maximum of 4 concurrent runs. [ ][ ]
Significant amounts of node maintenance was performed by Holger Levsen (eg. [ ][ ][ ][ ][ ][ ][ ] etc.) and Vagrant Cascadian (eg. [ ][ ][ ][ ][ ][ ][ ][ ]). Indeed, Vagrant Cascadian handled an extended power outage for the network running the Debian armhf architecture test infrastructure. This provided the incentive to replace the UPS batteries and consolidate infrastructure to reduce future UPS load. [ ] Elsewhere in our infrastructure, however, Holger Levsen also adjusted the email configuration for to deal with a new SMTP email attack. [ ]

Upstream patches The Reproducible Builds project tries to detects, dissects and 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: Separate to this, Vagrant Cascadian followed up with the relevant maintainers when reproducibility fixes were not included in newly-uploaded versions of the mm-common package in Debian this was quickly fixed, however. [ ]

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:

22 January 2024

Paul Tagliamonte: Writing a simulator to check phased array beamforming

Interested in future updates? Follow me on mastodon at Posts about will be tagged #hztools.

If you're on the Fediverse, I'd very much appreciate boosts on my toot!
While working on, I started to move my beamforming code from 2-D (meaning, beamforming to some specific angle on the X-Y plane for waves on the X-Y plane) to 3-D. I ll have more to say about that once I get around to publishing the code as soon as I m sure it s not completely wrong, but in the meantime I decided to write a simple simulator to visually check the beamformer against the textbooks. The results were pretty rad, so I figured I d throw together a post since it s interesting all on its own outside of beamforming as a general topic. I figured I d write this in Rust, since I ve been using Rust as my primary language over at zoo, and it s a good chance to learn the language better.
This post has some large GIFs

It make take a little bit to load depending on your internet connection. Sorry about that, I'm not clever enough to do better without doing tons of complex engineering work. They may be choppy while they load or something. I tried to compress an ensmall them, so if they're loaded but fuzzy, click on them to load a slightly larger version.
This post won t cover the basics of how phased arrays work or the specifics of calculating the phase offsets for each antenna, but I ll dig into how I wrote a simple simulator and how I wound up checking my phase offsets to generate the renders below.

Assumptions I didn t want to build a general purpose RF simulator, anything particularly generic, or something that would solve for any more than the things right in front of me. To do this as simply (and quickly all this code took about a day to write, including the beamforming math) I had to reduce the amount of work in front of me. Given that I was concerend with visualizing what the antenna pattern would look like in 3-D given some antenna geometry, operating frequency and configured beam, I made the following assumptions: All anetnnas are perfectly isotropic they receive a signal that is exactly the same strength no matter what direction the signal originates from. There s a single point-source isotropic emitter in the far-field (I modeled this as being 1 million meters away 1000 kilometers) of the antenna system. There is no noise, multipath, loss or distortion in the signal as it travels through space. Antennas will never interfere with each other.

2-D Polar Plots The last time I wrote something like this, I generated 2-D GIFs which show a radiation pattern, not unlike the polar plots you d see on a microphone. These are handy because it lets you visualize what the directionality of the antenna looks like, as well as in what direction emissions are captured, and in what directions emissions are nulled out. You can see these plots on spec sheets for antennas in both 2-D and 3-D form. Now, let s port the 2-D approach to 3-D and see how well it works out.

Writing the 3-D simulator As an EM wave travels through free space, the place at which you sample the wave controls that phase you observe at each time-step. This means, assuming perfectly synchronized clocks, a transmitter and receiver exactly one RF wavelength apart will observe a signal in-phase, but a transmitter and receiver a half wavelength apart will observe a signal 180 degrees out of phase. This means that if we take the distance between our point-source and antenna element, divide it by the wavelength, we can use the fractional part of the resulting number to determine the phase observed. If we multiply that number (in the range of 0 to just under 1) by tau, we can generate a complex number by taking the cos and sin of the multiplied phase (in the range of 0 to tau), assuming the transmitter is emitting a carrier wave at a static amplitude and all clocks are in perfect sync.
 let observed_phases: Vec<Complex> = antennas
.map( antenna   
let distance = (antenna - tx).magnitude();
let distance = distance - (distance as i64 as f64);
((distance / wavelength) * TAU)
.map( phase  Complex(phase.cos(), phase.sin()))
At this point, given some synthetic transmission point and each antenna, we know what the expected complex sample would be at each antenna. At this point, we can adjust the phase of each antenna according to the beamforming phase offset configuration, and add up every sample in order to determine what the entire system would collectively produce a sample as.
 let beamformed_phases: Vec<Complex> = ...;
let magnitude = beamformed_phases
.map( (beamformed, observed)  observed * beamformed)
.reduce( acc, el  acc + el)
Armed with this information, it s straight forward to generate some number of (Azimuth, Elevation) points to sample, generate a transmission point far away in that direction, resolve what the resulting Complex sample would be, take its magnitude, and use that to create an (x, y, z) point at (azimuth, elevation, magnitude). The color attached two that point is based on its distance from (0, 0, 0). I opted to use the Life Aquatic table for this one. After this process is complete, I have a point cloud of ((x, y, z), (r, g, b)) points. I wrote a small program using kiss3d to render point cloud using tons of small spheres, and write out the frames to a set of PNGs, which get compiled into a GIF. Now for the fun part, let s take a look at some radiation patterns!

1x4 Phased Array The first configuration is a phased array where all the elements are in perfect alignment on the y and z axis, and separated by some offset in the x axis. This configuration can sweep 180 degrees (not the full 360), but can t be steared in elevation at all. Let s take a look at what this looks like for a well constructed 1x4 phased array: And now let s take a look at the renders as we play with the configuration of this array and make sure things look right. Our initial quarter-wavelength spacing is very effective and has some outstanding performance characteristics. Let s check to see that everything looks right as a first test. Nice. Looks perfect. When pointing forward at (0, 0), we d expect to see a torus, which we do. As we sweep between 0 and 360, astute observers will notice the pattern is mirrored along the axis of the antennas, when the beam is facing forward to 0 degrees, it ll also receive at 180 degrees just as strong. There s a small sidelobe that forms when it s configured along the array, but it also becomes the most directional, and the sidelobes remain fairly small.

Long compared to the wavelength (1 ) Let s try again, but rather than spacing each antenna of a wavelength apart, let s see about spacing each antenna 1 of a wavelength apart instead. The main lobe is a lot more narrow (not a bad thing!), but some significant sidelobes have formed (not ideal). This can cause a lot of confusion when doing things that require a lot of directional resolution unless they re compensated for.

Going from ( to 5 ) The last model begs the question - what do things look like when you separate the antennas from each other but without moving the beam? Let s simulate moving our antennas but not adjusting the configured beam or operating frequency. Very cool. As the spacing becomes longer in relation to the operating frequency, we can see the sidelobes start to form out of the end of the antenna system.

2x2 Phased Array The second configuration I want to try is a phased array where the elements are in perfect alignment on the z axis, and separated by a fixed offset in either the x or y axis by their neighbor, forming a square when viewed along the x/y axis. Let s take a look at what this looks like for a well constructed 2x2 phased array: Let s do the same as above and take a look at the renders as we play with the configuration of this array and see what things look like. This configuration should suppress the sidelobes and give us good performance, and even give us some amount of control in elevation while we re at it. Sweet. Heck yeah. The array is quite directional in the configured direction, and can even sweep a little bit in elevation, a definite improvement from the 1x4 above.

Long compared to the wavelength (1 ) Let s do the same thing as the 1x4 and take a look at what happens when the distance between elements is long compared to the frequency of operation say, 1 of a wavelength apart? What happens to the sidelobes given this spacing when the frequency of operation is much different than the physical geometry? Mesmerising. This is my favorate render. The sidelobes are very fun to watch come in and out of existence. It looks absolutely other-worldly.

Going from ( to 5 ) Finally, for completeness' sake, what do things look like when you separate the antennas from each other just as we did with the 1x4? Let s simulate moving our antennas but not adjusting the configured beam or operating frequency. Very very cool. The sidelobes wind up turning the very blobby cardioid into an electromagnetic dog toy. I think we ve proven to ourselves that using a phased array much outside its designed frequency of operation seems like a real bad idea.

Future Work Now that I have a system to test things out, I m a bit more confident that my beamforming code is close to right! I d love to push that code over the line and blog about it, since it s a really interesting topic on its own. Once I m sure the code involved isn t full of lies, I ll put it up on the hztools org, and post about it here and on mastodon.

26 December 2023

Russ Allbery: krb5-strength 3.3

krb5-strength is a toolkit of plugins and support programs for password strength checking for Kerberos KDCs, either Heimdal or MIT. It also includes a password history mechanism for Heimdal KDCs. This is a maintenance release, since there hadn't been a new release since 2020. It contains the normal sort of build system and portability updates, and the routine bump in the number of hash iterations used for the history mechanism to protect against (some) brute force attacks. It also includes an RPM spec file contributed by Daria Phoebe Brashear, and some changes to the Perl dependencies to track current community recommendations. You can get the latest version from the krb5-strength distribution page.

13 December 2023

Melissa Wen: 15 Tips for Debugging Issues in the AMD Display Kernel Driver

A self-help guide for examining and debugging the AMD display driver within the Linux kernel/DRM subsystem. It s based on my experience as an external developer working on the driver, and are shared with the goal of helping others navigate the driver code. Acknowledgments: These tips were gathered thanks to the countless help received from AMD developers during the driver development process. The list below was obtained by examining open source code, reviewing public documentation, playing with tools, asking in public forums and also with the help of my former GSoC mentor, Rodrigo Siqueira.

Pre-Debugging Steps: Before diving into an issue, it s crucial to perform two essential steps: 1) Check the latest changes: Ensure you re working with the latest AMD driver modifications located in the amd-staging-drm-next branch maintained by Alex Deucher. You may also find bug fixes for newer kernel versions on branches that have the name pattern drm-fixes-<date>. 2) Examine the issue tracker: Confirm that your issue isn t already documented and addressed in the AMD display driver issue tracker. If you find a similar issue, you can team up with others and speed up the debugging process.

Understanding the issue: Do you really need to change this? Where should you start looking for changes? 3) Is the issue in the AMD kernel driver or in the userspace?: Identifying the source of the issue is essential regardless of the GPU vendor. Sometimes this can be challenging so here are some helpful tips:
  • Record the screen: Capture the screen using a recording app while experiencing the issue. If the bug appears in the capture, it s likely a userspace issue, not the kernel display driver.
  • Analyze the dmesg log: Look for error messages related to the display driver in the dmesg log. If the error message appears before the message [drm] Display Core v... , it s not likely a display driver issue. If this message doesn t appear in your log, the display driver wasn t fully loaded and you will see a notification that something went wrong here.
4) AMD Display Manager vs. AMD Display Core: The AMD display driver consists of two components:
  • Display Manager (DM): This component interacts directly with the Linux DRM infrastructure. Occasionally, issues can arise from misinterpretations of DRM properties or features. If the issue doesn t occur on other platforms with the same AMD hardware - for example, only happens on Linux but not on Windows - it s more likely related to the AMD DM code.
  • Display Core (DC): This is the platform-agnostic part responsible for setting and programming hardware features. Modifications to the DC usually require validation on other platforms, like Windows, to avoid regressions.
5) Identify the DC HW family: Each AMD GPU has variations in its hardware architecture. Features and helpers differ between families, so determining the relevant code for your specific hardware is crucial.
  • Find GPU product information in Linux/AMD GPU documentation
  • Check the dmesg log for the Display Core version (since this commit in Linux kernel 6.3v). For example:
    • [drm] Display Core v3.2.241 initialized on DCN 2.1
    • [drm] Display Core v3.2.237 initialized on DCN 3.0.1

Investigating the relevant driver code: Keep from letting unrelated driver code to affect your investigation. 6) Narrow the code inspection down to one DC HW family: the relevant code resides in a directory named after the DC number. For example, the DCN 3.0.1 driver code is located at drivers/gpu/drm/amd/display/dc/dcn301. We all know that the AMD s shared code is huge and you can use these boundaries to rule out codes unrelated to your issue. 7) Newer families may inherit code from older ones: you can find dcn301 using code from dcn30, dcn20, dcn10 files. It s crucial to verify which hooks and helpers your driver utilizes to investigate the right portion. You can leverage ftrace for supplemental validation. To give an example, it was useful when I was updating DCN3 color mapping to correctly use their new post-blending color capabilities, such as: Additionally, you can use two different HW families to compare behaviours. If you see the issue in one but not in the other, you can compare the code and understand what has changed and if the implementation from a previous family doesn t fit well the new HW resources or design. You can also count on the help of the community on the Linux AMD issue tracker to validate your code on other hardware and/or systems. This approach helped me debug a 2-year-old issue where the cursor gamma adjustment was incorrect in DCN3 hardware, but working correctly for DCN2 family. I solved the issue in two steps, thanks for community feedback and validation: 8) Check the hardware capability screening in the driver: You can currently find a list of display hardware capabilities in the drivers/gpu/drm/amd/display/dc/dcn*/dcn*_resource.c file. More precisely in the dcn*_resource_construct() function. Using DCN301 for illustration, here is the list of its hardware caps:
	 *  Resource + asic cap harcoding                *
	pool->base.underlay_pipe_index = NO_UNDERLAY_PIPE;
	pool->base.pipe_count = pool->base.res_cap->num_timing_generator;
	pool->base.mpcc_count = pool->base.res_cap->num_timing_generator;
	dc->caps.max_downscale_ratio = 600;
	dc->caps.i2c_speed_in_khz = 100;
	dc->caps.i2c_speed_in_khz_hdcp = 5; /*1.4 w/a enabled by default*/
	dc->caps.max_cursor_size = 256;
	dc->caps.min_horizontal_blanking_period = 80;
	dc->caps.dmdata_alloc_size = 2048;
	dc->caps.max_slave_planes = 2;
	dc->caps.max_slave_yuv_planes = 2;
	dc->caps.max_slave_rgb_planes = 2;
	dc->caps.is_apu = true;
	dc->caps.post_blend_color_processing = true;
	dc->caps.force_dp_tps4_for_cp2520 = true;
	dc->caps.extended_aux_timeout_support = true;
	dc->caps.dmcub_support = true;
	/* Color pipeline capabilities */
	dc->caps.color.dpp.dcn_arch = 1;
	dc->caps.color.dpp.input_lut_shared = 0;
	dc->caps.color.dpp.icsc = 1;
	dc->caps.color.dpp.dgam_ram = 0; // must use gamma_corr
	dc->caps.color.dpp.dgam_rom_caps.srgb = 1;
	dc->caps.color.dpp.dgam_rom_caps.bt2020 = 1;
	dc->caps.color.dpp.dgam_rom_caps.gamma2_2 = 1;
	dc->caps.color.dpp.dgam_rom_caps.pq = 1;
	dc->caps.color.dpp.dgam_rom_caps.hlg = 1;
	dc->caps.color.dpp.post_csc = 1;
	dc->caps.color.dpp.gamma_corr = 1;
	dc->caps.color.dpp.dgam_rom_for_yuv = 0;
	dc->caps.color.dpp.hw_3d_lut = 1;
	dc->caps.color.dpp.ogam_ram = 1;
	// no OGAM ROM on DCN301
	dc->caps.color.dpp.ogam_rom_caps.srgb = 0;
	dc->caps.color.dpp.ogam_rom_caps.bt2020 = 0;
	dc->caps.color.dpp.ogam_rom_caps.gamma2_2 = 0;
	dc->caps.color.dpp.ogam_rom_caps.pq = 0;
	dc->caps.color.dpp.ogam_rom_caps.hlg = 0;
	dc->caps.color.dpp.ocsc = 0;
	dc->caps.color.mpc.gamut_remap = 1;
	dc->caps.color.mpc.num_3dluts = pool->base.res_cap->num_mpc_3dlut; //2
	dc->caps.color.mpc.ogam_ram = 1;
	dc->caps.color.mpc.ogam_rom_caps.srgb = 0;
	dc->caps.color.mpc.ogam_rom_caps.bt2020 = 0;
	dc->caps.color.mpc.ogam_rom_caps.gamma2_2 = 0;
	dc->caps.color.mpc.ogam_rom_caps.pq = 0;
	dc->caps.color.mpc.ogam_rom_caps.hlg = 0;
	dc->caps.color.mpc.ocsc = 1;
	dc->caps.dp_hdmi21_pcon_support = true;
	/* read VBIOS LTTPR caps */
	if (ctx->dc_bios->funcs->get_lttpr_caps)  
		enum bp_result bp_query_result;
		uint8_t is_vbios_lttpr_enable = 0;
		bp_query_result = ctx->dc_bios->funcs->get_lttpr_caps(ctx->dc_bios, &is_vbios_lttpr_enable);
		dc->caps.vbios_lttpr_enable = (bp_query_result == BP_RESULT_OK) && !!is_vbios_lttpr_enable;
	if (ctx->dc_bios->funcs->get_lttpr_interop)  
		enum bp_result bp_query_result;
		uint8_t is_vbios_interop_enabled = 0;
		bp_query_result = ctx->dc_bios->funcs->get_lttpr_interop(ctx->dc_bios, &is_vbios_interop_enabled);
		dc->caps.vbios_lttpr_aware = (bp_query_result == BP_RESULT_OK) && !!is_vbios_interop_enabled;
Keep in mind that the documentation of color capabilities are available at the Linux kernel Documentation.

Understanding the development history: What has brought us to the current state? 9) Pinpoint relevant commits: Use git log and git blame to identify commits targeting the code section you re interested in. 10) Track regressions: If you re examining the amd-staging-drm-next branch, check for regressions between DC release versions. These are defined by DC_VER in the drivers/gpu/drm/amd/display/dc/dc.h file. Alternatively, find a commit with this format drm/amd/display: 3.2.221 that determines a display release. It s useful for bisecting. This information helps you understand how outdated your branch is and identify potential regressions. You can consider each DC_VER takes around one week to be bumped. Finally, check testing log of each release in the report provided on the amd-gfx mailing list, such as this one Tested-by: Daniel Wheeler:

Reducing the inspection area: Focus on what really matters. 11) Identify involved HW blocks: This helps isolate the issue. You can find more information about DCN HW blocks in the DCN Overview documentation. In summary:
  • Plane issues are closer to HUBP and DPP.
  • Blending/Stream issues are closer to MPC, OPP and OPTC. They are related to DRM CRTC subjects.
This information was useful when debugging a hardware rotation issue where the cursor plane got clipped off in the middle of the screen. Finally, the issue was addressed by two patches: 12) Issues around bandwidth (glitches) and clocks: May be affected by calculations done in these HW blocks and HW specific values. The recalculation equations are found in the DML folder. DML stands for Display Mode Library. It s in charge of all required configuration parameters supported by the hardware for multiple scenarios. See more in the AMD DC Overview kernel docs. It s a math library that optimally configures hardware to find the best balance between power efficiency and performance in a given scenario. Finding some clk variables that affect device behavior may be a sign of it. It s hard for a external developer to debug this part, since it involves information from HW specs and firmware programming that we don t have access. The best option is to provide all relevant debugging information you have and ask AMD developers to check the values from your suspicions.
  • Do a trick: If you suspect the power setup is degrading performance, try setting the amount of power supplied to the GPU to the maximum and see if it affects the system behavior with this command: sudo bash -c "echo high > /sys/class/drm/card0/device/power_dpm_force_performance_level"
I learned it when debugging glitches with hardware cursor rotation on Steam Deck. My first attempt was changing the clock calculation. In the end, Rodrigo Siqueira proposed the right solution targeting bandwidth in two steps:

Checking implicit programming and hardware limitations: Bring implicit programming to the level of consciousness and recognize hardware limitations. 13) Implicit update types: Check if the selected type for atomic update may affect your issue. The update type depends on the mode settings, since programming some modes demands more time for hardware processing. More details in the source code:
/* Surface update type is used by dc_update_surfaces_and_stream
 * The update type is determined at the very beginning of the function based
 * on parameters passed in and decides how much programming (or updating) is
 * going to be done during the call.
 * UPDATE_TYPE_FAST is used for really fast updates that do not require much
 * logical calculations or hardware register programming. This update MUST be
 * ISR safe on windows. Currently fast update will only be used to flip surface
 * address.
 * UPDATE_TYPE_MED is used for slower updates which require significant hw
 * re-programming however do not affect bandwidth consumption or clock
 * requirements. At present, this is the level at which front end updates
 * that do not require us to run bw_calcs happen. These are in/out transfer func
 * updates, viewport offset changes, recout size changes and pixel
depth changes.
 * This update can be done at ISR, but we want to minimize how often
this happens.
 * UPDATE_TYPE_FULL is slow. Really slow. This requires us to recalculate our
 * bandwidth and clocks, possibly rearrange some pipes and reprogram
anything front
 * end related. Any time viewport dimensions, recout dimensions,
scaling ratios or
 * gamma need to be adjusted or pipe needs to be turned on (or
disconnected) we do
 * a full update. This cannot be done at ISR level and should be a rare event.
 * Unless someone is stress testing mpo enter/exit, playing with
colour or adjusting
 * underscan we don't expect to see this call at all.
enum surface_update_type  
UPDATE_TYPE_FAST, /* super fast, safe to execute in isr */
UPDATE_TYPE_MED,  /* ISR safe, most of programming needed, no bw/clk change*/
UPDATE_TYPE_FULL, /* may need to shuffle resources */

Using tools: Observe the current state, validate your findings, continue improvements. 14) Use AMD tools to check hardware state and driver programming: help on understanding your driver settings and checking the behavior when changing those settings.
  • DC Visual confirmation: Check multiple planes and pipe split policy.
  • DTN logs: Check display hardware state, including rotation, size, format, underflow, blocks in use, color block values, etc.
  • UMR: Check ASIC info, register values, KMS state - links and elements (framebuffers, planes, CRTCs, connectors). Source: UMR project documentation
15) Use generic DRM/KMS tools:
  • IGT test tools: Use generic KMS tests or develop your own to isolate the issue in the kernel space. Compare results across different GPU vendors to understand their implementations and find potential solutions. Here AMD also has specific IGT tests for its GPUs that is expect to work without failures on any AMD GPU. You can check results of HW-specific tests using different display hardware families or you can compare expected differences between the generic workflow and AMD workflow.
  • drm_info: This tool summarizes the current state of a display driver (capabilities, properties and formats) per element of the DRM/KMS workflow. Output can be helpful when reporting bugs.

Don t give up! Debugging issues in the AMD display driver can be challenging, but by following these tips and leveraging available resources, you can significantly improve your chances of success. Worth mentioning: This blog post builds upon my talk, I m not an AMD expert, but presented at the 2022 XDC. It shares guidelines that helped me debug AMD display issues as an external developer of the driver. Open Source Display Driver: The Linux kernel/AMD display driver is open source, allowing you to actively contribute by addressing issues listed in the official tracker. Tackling existing issues or resolving your own can be a rewarding learning experience and a valuable contribution to the community. Additionally, the tracker serves as a valuable resource for finding similar bugs, troubleshooting tips, and suggestions from AMD developers. Finally, it s a platform for seeking help when needed. Remember, contributing to the open source community through issue resolution and collaboration is mutually beneficial for everyone involved.

4 December 2023

Russ Allbery: Cumulative haul

I haven't done one of these in quite a while, long enough that I've already read and reviewed many of these books. John Joseph Adams (ed.) The Far Reaches (sff anthology)
Poul Anderson The Shield of Time (sff)
Catherine Asaro The Phoenix Code (sff)
Catherine Asaro The Veiled Web (sff)
Travis Baldree Bookshops & Bonedust (sff)
Sue Burke Semiosis (sff)
Jacqueline Carey Cassiel's Servant (sff)
Rob Copeland The Fund (nonfiction)
Mar Delaney Wolf Country (sff)
J.S. Dewes The Last Watch (sff)
J.S. Dewes The Exiled Fleet (sff)
Mike Duncan Hero of Two Worlds (nonfiction)
Mike Duncan The Storm Before the Storm (nonfiction)
Kate Elliott King's Dragon (sff)
Zeke Faux Number Go Up (nonfiction)
Nicola Griffith Menewood (sff)
S.L. Huang The Water Outlaws (sff)
Alaya Dawn Johnson The Library of Broken Worlds (sff)
T. Kingfisher Thornhedge (sff)
Naomi Kritzer Liberty's Daughter (sff)
Ann Leckie Translation State (sff)
Michael Lewis Going Infinite (nonfiction)
Jenna Moran Magical Bears in the Context of Contemporary Political Theory (sff collection)
Ari North Love and Gravity (graphic novel)
Ciel Pierlot Bluebird (sff)
Terry Pratchett A Hat Full of Sky (sff)
Terry Pratchett Going Postal (sff)
Terry Pratchett Thud! (sff)
Terry Pratchett Wintersmith (sff)
Terry Pratchett Making Money (sff)
Terry Pratchett Unseen Academicals (sff)
Terry Pratchett I Shall Wear Midnight (sff)
Terry Pratchett Snuff (sff)
Terry Pratchett Raising Steam (sff)
Terry Pratchett The Shepherd's Crown (sff)
Aaron A. Reed 50 Years of Text Games (nonfiction)
Dashka Slater Accountable (nonfiction)
Rory Stewart The Marches (nonfiction)
Emily Tesh Silver in the Wood (sff)
Emily Tesh Drowned Country (sff)
Valerie Vales Chilling Effect (sff)
Martha Wells System Collapse (sff)
Martha Wells Witch King (sff)

23 November 2023

Bits from Debian: rsync address change

The proposed and previously announced changes to the rsync service have become effective with the rsync:// address now being discontinued. The worldwide Debian mirrors network has served via both HTTP and rsync. As part of improving the reliability of the service for users, the Debian mirrors team is separating the access methods to different host names: rsync service on has stopped, and we encourage anyone using the service to migrate to the new host name as soon as possible. If you are currently using rsync to the debian-archive from a server that forms part of the rotation, we also encourage Administrators to move to the new service name. This will allow us to better manage which back-end servers offer rsync service in future. Note that due to its nature the content of does not change frequently - generally there will be several months, possibly more than a year, between updates - so checking for updates more than once a day is unnecessary. For additional information please reach out to the Debian Mirrors Team maillist.

10 October 2023

Matthias Klumpp: How to indicate device compatibility for your app in MetaInfo data

At the moment I am hard at work putting together the final bits for the AppStream 1.0 release (hopefully to be released this month). The new release comes with many new new features, an improved developer API and removal of most deprecated things (so it carefully breaks compatibility with very old data and the previous C API). One of the tasks for the upcoming 1.0 release was #481 asking about a formal way to distinguish Linux phone applications from desktop applications. AppStream infamously does not support any is-for-phone label for software components, instead the decision whether something is compatible with a device is based the the device s capabilities and the component s requirements. This allows for truly adaptive applications to describe their requirements correctly, and does not lock us into form factors going into the future, as there are many and the feature range between a phone, a tablet and a tiny laptop is quite fluid. Of course the match to current device capabilities check does not work if you are a website ranking phone compatibility. It also does not really work if you are a developer and want to know which devices your component / application will actually be considered compatible with. One goal for AppStream 1.0 is to have its library provide more complete building blocks to software centers. Instead of just a here s the data, interpret it according to the specification API, libappstream now interprets the specification for the application and provides API to handle most common operations like checking device compatibility. For developers, AppStream also now implements a few virtual chassis configurations , to roughly gauge which configurations a component may be compatible with. To test the new code, I ran it against the large Debian and Flatpak repositories to check which applications are considered compatible with what chassis/device type already. The result was fairly disastrous, with many applications not specifying compatibility correctly (many do, but it s by far not the norm!). Which brings me to the actual topic of this blog post: Very few seem to really know how to mark an application compatible with certain screen sizes and inputs! This is most certainly a matter of incomplete guides and good templates, so maybe this post can help with that a bit:

The ultimate cheat-sheet to mark your app chassis-type compatible As a quick reminder, compatibility is indicated using AppStream s relations system: A requires relation indicates that the system will not run at all or will run terribly if the requirement is not met. If the requirement is not met, it should not be installable on a system. A recommends relation means that it would be advantageous to have the recommended items, but it s not essential to run the application (it may run with a degraded experience without the recommended things though). And a supports relation means a given interface/device/control/etc. is supported by this application, but the application may work completely fine without it.

I have a desktop-only application A desktop-only application is characterized by needing a larger screen to fit the application, and requiring a physical keyboard and accurate mouse input. This type is assumed by default if no capabilities are set for an application, but it s better to be explicit. This is the metadata you need:
<component type="desktop-application">
With this requires relation, you require a small-desktop sized screen (at least 768 device-independent pixels (dp) on its smallest edge) and require a keyboard and mouse to be present / connectable. Of course, if your application needs more minimum space, adjust the requirement accordingly. Note that if the requirement is not met, your application may not be offered for installation.
Note: Device-independent / logical pixels One logical pixel (= device independent pixel) roughly corresponds to the visual angle of one pixel on a device with a pixel density of 96 dpi (for historical X11 reasons) and a distance from the observer of about 52 cm, making the physical pixel about 0.26 mm in size. When using logical pixels as unit, they might not always map to exact physical lengths as their exact size is defined by the device providing the display. They do however accurately depict the maximum amount of pixels that can be drawn in the depicted direction on the device s display space. AppStream always uses logical pixels when measuring lengths in pixels.

I have an application that works on mobile and on desktop / an adaptive app Adaptive applications have fewer hard requirements, but a wide range of support for controls and screen sizes. For example, they support touch input, unlike desktop apps. An example MetaInfo snippet for these kind of apps may look like this:
<component type="desktop-application">
Unlike the pure desktop application, this adaptive application requires a much smaller lowest display edge length, and also supports touch input, in addition to keyboard and mouse/touchpad precision input.

I have a pure phone/table app Making an application a pure phone application is tricky: We need to mark it as compatible with phones only, while not completely preventing its installation on non-phone devices (even though its UI is horrible, you may want to test the app, and software centers may allow its installation when requested explicitly even if they don t show it by default). This is how to achieve that result:
<component type="desktop-application">
    <display_length compare="lt">1280</display_length>
We require a phone-sized display minimum edge size (adjust to a value that is fit for your app!), but then also recommend the screen to have a smaller edge size than a larger tablet/laptop, while also recommending touch input and not listing any support for keyboard and mouse. Please note that this blog post is of course not a comprehensive guide, so if you want to dive deeper into what you can do with requires/recommends/suggests/supports, you may want to have a look at the relations tags described in the AppStream specification.

Validation It is still easy to make mistakes with the system requirements metadata, which is why AppStream 1.0 will provide more commands to check MetaInfo files for system compatibility. Current pre-1.0 AppStream versions already have an is-satisfied command to check if the application is compatible with the currently running operating system:
:~$ appstreamcli is-satisfied ./org.example.adaptive_app.metainfo.xml
Relation check for: */*/*/org.example.adaptive_app/*
   Unable to check display size: Can not read information without GUI toolkit access.
   No recommended items are set for this software.
   Physical keyboard found.
   Pointing device (e.g. a mouse or touchpad) found.
   This software supports touch input.
In addition to this command, AppStream 1.0 will introduce a new one as well: check-syscompat. This command will check the component against libappstream s mock system configurations that define a most common (whatever that is at the time) configuration for a respective chassis type. If you pass the --details flag, you can even get an explanation why the component was considered or not considered for a specific chassis type:
:~$ appstreamcli check-syscompat --details ./org.example.phoneapp.metainfo.xml
Chassis compatibility check for: */*/*/org.example.phoneapp/*
   recommends: This software recommends a display with its shortest edge
   being << 1280 px in size, but the display of this device has 1280 px.
   recommends: This software recommends a touch input device.
   recommends: This software recommends a display with its shortest edge 
   being << 1280 px in size, but the display of this device has 1280 px.
   recommends: This software recommends a touch input device.
   requires: This software needs a display for graphical content.
   recommends: This software needs a display for graphical content.
   recommends: This software recommends a touch input device.
   Compatible (100%)
   Compatible (100%)
I hope this is helpful for people. Happy metadata writing!

6 October 2023

Russ Allbery: Review: The Far Reaches

Review: The Far Reaches, edited by John Joseph Adams
Publisher: Amazon Original Stories
Copyright: June 2023
ISBN: 1-6625-1572-3
ISBN: 1-6625-1622-3
ISBN: 1-6625-1503-0
ISBN: 1-6625-1567-7
ISBN: 1-6625-1678-9
ISBN: 1-6625-1533-2
Format: Kindle
Pages: 219
Amazon has been releasing anthologies of original short SFF with various guest editors, free for Amazon Prime members. I previously tried Black Stars (edited by Nisi Shawl and Latoya Peterson) and Forward (edited by Blake Crouch). Neither were that good, but the second was much worse than the first. Amazon recently released a new collection, this time edited by long-standing SFF anthology editor John Joseph Adams and featuring a new story by Ann Leckie, which sounded promising enough to give them another chance. The definition of insanity is doing the same thing over and over again and expecting different results. As with the previous anthologies, each story is available separately for purchase or Amazon Prime "borrowing" with separate ISBNs. The sidebar cover is for the first in the sequence. Unlike the previous collections, which were longer novelettes or novellas, my guess is all of these are in the novelette range. (I did not do a word count.) If you're considering this anthology, read the Okorafor story ("Just Out of Jupiter's Reach"), consider "How It Unfolds" by James S.A. Corey, and avoid the rest. "How It Unfolds" by James S.A. Corey: Humans have invented a new form of physics called "slow light," which can duplicate any object that is scanned. The energy expense is extremely high, so the result is not a post-scarcity paradise. What the technology does offer, however, is a possible route to interstellar colonization: duplicate a team of volunteers and a ship full of bootstrapping equipment, and send copies to a bunch of promising-looking exoplanets. One of them might succeed. The premise is interesting. The twists Corey adds on top are even better. What can be duplicated once can be duplicated again, perhaps with more information. This is a lovely science fiction idea story that unfortunately bogs down because the authors couldn't think of anywhere better to go with it than relationship drama. I found the focus annoying, but the ideas are still very neat. (7) "Void" by Veronica Roth: A maintenance worker on a slower-than-light passenger ship making the run between Sol and Centauri unexpectedly is called to handle a dead body. A passenger has been murdered, two days outside the Sol system. Ace is in no way qualified to investigate the murder, nor is it her job, but she's watched a lot of crime dramas and she has met the victim before. The temptation to start poking around is impossible to resist. It's been a long time since I've read a story built around the differing experiences of time for people who stay on planets and people who spend most of their time traveling at relativistic speeds. It's a bit of a retro idea from an earlier era of science fiction, but it's still a good story hook for a murder mystery. None of the characters are that memorable and Roth never got me fully invested in the story, but this was still a pleasant way to pass the time. (6) "Falling Bodies" by Rebecca Roanhorse: Ira is the adopted son of a Genteel senator. He was a social experiment in civilizing the humans: rescue a human orphan and give him the best of Genteel society to see if he could behave himself appropriately. The answer was no, which is how Ira finds himself on Long Reach Station with a parole officer and a schooling opportunity, hopefully far enough from his previous mistakes for a second chance. Everyone else seems to like Rebecca Roanhorse's writing better than I do, and this is no exception. Beneath the veneer of a coming-of-age story with a twist of political intrigue, this is brutal, depressing, and awful, with an ending that needs a lot of content warnings. I'm sorry that I read it. (3) "The Long Game" by Ann Leckie: The Imperial Radch trilogy are some of my favorite science fiction novels of all time, but I am finding Leckie's other work a bit hit and miss. I have yet to read a novel of hers that I didn't like, but the short fiction I've read leans more heavily into exploring weird and alien perspectives, which is not my favorite part of her work. This story is firmly in that category: the first-person protagonist is a small tentacled alien creature, a bit like a swamp-dwelling octopus. I think I see what Leckie is doing here: balancing cynicism and optimism, exploring how lifespans influence thinking and planning, and making some subtle points about colonialism. But as a reading experience, I didn't enjoy it. I never liked any of the characters, and the conclusion of the story is the unsettling sort of main-character optimism that seems rather less optimistic to the reader. (4) "Just Out of Jupiter's Reach" by Nnedi Okorafor: K rm n scientists have found a way to grow living ships that can achieve a symbiosis with a human pilot, but the requirements for that symbiosis are very strict and hard to predict. The result was a planet-wide search using genetic testing to find the rare and possibly nonexistent matches. They found seven people. The deal was simple: spend ten years in space, alone, in her ship. No contact with any other human except at the midpoint, when the seven ships were allowed to meet up for a week. Two million euros a year, for as long as she followed the rules, and the opportunity to be part of a great experiment, providing data that will hopefully lead to humans becoming a spacefaring species. The core of this story is told during the seven days in the middle of the mission, and thus centers on people unfamiliar with human contact trying to navigate social relationships after five years in symbiotic ships that reshape themselves to their whims and personalities. The ships themselves link so that the others can tour, which offers both a good opportunity for interesting description and a concretized metaphor about meeting other people. I adore symbiotic spaceships, so this story had me at the premise. The surface plot is very psychological, and I didn't entirely click with it, but the sense of wonder vibes beneath that surface were wonderful. It also feels fresh and new: I've seen most of the ideas before, but not presented or written this way, or approached from quite this angle. Definitely the best story of the anthology. (8) "Slow Time Between the Stars" by John Scalzi: This, on the other hand, was a complete waste of time, redeemed only by being the shortest "story" in the collection. "Story" is generous, since there's only one character and a very dry, linear plot that exists only to make a philosophical point. "Speculative essay" may be closer. The protagonist is the artificial intelligence responsible for Earth's greatest interstellar probe. It is packed with a repository of all of human knowledge and the raw material to create life. Its mission is to find an exoplanet capable of sustaining that life, and then recreate it and support it. The plot, such as it is, follows the AI's decision to abandon that mission and cut off contact with Earth, for reasons that it eventually explains. Every possible beat of this story hit me wrong. The sense of wonder attaches to the most prosaic things and skips over the moments that could have provoked real wonder. The AI is both unbelievable and irritating, with all of the smug self-confidence of an Internet reply guy. The prose is overwrought in all the wrong places ("the finger of God, offering the spark to animate the dirt of another world" would totally be this AI's profile quote under their forum avatar). The only thing I liked about the story is the ethical point that it slowly meanders into, which I think I might agree with and at least find plausible. But it's delivered by the sort of character I would actively leave rooms to avoid, in a style that's about as engrossing as a tax form. Avoid. (2) Rating: 5 out of 10

30 September 2023

Ian Jackson: DKIM: rotate and publish your keys

If you are an email system administrator, you are probably using DKIM to sign your outgoing emails. You should be rotating the key regularly and automatically, and publishing old private keys. I have just released dkim-rotate 1.0; dkim-rotate is a tool to do this key rotation and publication. If you are an email user, your email provider ought to be doing this. If this is not done, your emails are non-repudiable , meaning that if they are leaked, anyone (eg, journalists, haters) can verify that they are authentic, and prove that to others. This is not desirable (for you). Non-repudiation of emails is undesirable This problem was described at some length in Matthew Green s article Ok Google: please publish your DKIM secret keys. Avoiding non-repudiation sounds a bit like lying. After all, I m advising creating a situation where some people can t verify that something is true, even though it is. So I m advocating casting doubt. Crucially, though, it s doubt about facts that ought to be private. When you send an email, that s between you and the recipient. Normally you don t intend for anyone, anywhere, who happens to get a copy, to be able to verify that it was really you that sent it. In practical terms, this verifiability has already been used by journalists to verify stolen emails. Associated Press provide a verification tool. Advice for all email users As a user, you probably don t want your emails to be non-repudiable. (Other people might want to be able to prove you sent some email, but your email system ought to serve your interests, not theirs.) So, your email provider ought to be rotating their DKIM keys, and publishing their old ones. At a rough guess, your provider probably isn t :-(. How to tell by looking at email headers A quick and dirty way to guess is to have a friend look at the email headers of a message you sent. (It is important that the friend uses a different email provider, since often DKIM signatures are not applied within a single email system.) If your friend sees a DKIM-Signature header then the message is DKIM signed. If they don t, then it wasn t. Most email traversing the public internet is DKIM signed nowadays; so if they don t see the header probably they re not looking using the right tools, or they re actually on the same email system as you. In messages signed by a system running dkim-rotate, there will also be a header about the key rotation, to notify potential verifiers of the situation. Other systems that avoid non-repudiation-through-DKIM might do something similar. dkim-rotate s header looks like this:
But an email system might do half of the job of dkim-rotate: regularly rotating the key would cause the signatures of old emails to fail to verify, which is a good start. In that case there probably won t be such a header. Testing verification of new and old messages You can also try verifying the signatures. This isn t entirely straightforward, especially if you don t have access to low-level mail tooling. Your friend will need to be able to save emails as raw whole headers and body, un-decoded, un-rendered. If your friend is using a traditional Unix mail program, they should save the message as an mbox file. Otherwise, ProPublica have instructions for attaching and transferring and obtaining the raw email. (Scroll down to How to Check DKIM and ARC .) Checking that recent emails are verifiable Firstly, have your friend test that they can in fact verify a DKIM signature. This will demonstrate that the next test, where the verification is supposed to fail, is working properly and fails for the right reasons. Send your friend a test email now, and have them do this on a Linux system:
    # save the message as test-email.mbox
    apt install libmail-dkim-perl # or equivalent on another distro
    dkimproxy-verify <test-email.mbox
You should see output containing something like this:
    originator address:
    signature identity:
    verify result: pass
If the output ontains verify result: fail (body has been altered) then probably your friend didn t manage to faithfully save the unalterered raw message. Checking old emails cannot be verified When you both have that working, have your friend find an older email of yours, from (say) month ago. Perform the same steps. Hopefully they will see something like this:
    originator address:
    signature identity:
    verify result: fail (bad RSA signature)
or maybe
    verify result: invalid (public key: not available)
This indicates that this old email can no longer be verified. That s good: it means that anyone who steals a copy, can t verify it either. If it s leaked, the journalist who receives it won t know it s genuine and unmodified; they should then be suspicious. If your friend sees verify result: pass, then they have verified that that old email of yours is genuine. Anyone who had a copy of the mail can do that. This is good for email thieves, but not for you. For email admins: announcing dkim-rotate 1.0 I have been running dkim-rotate 0.4 on my infrastructure, since last August. and I had entirely forgotten about it: it has run flawlessly for a year. I was reminded of the topic by seeing DKIM in other blog posts. Obviously, it is time to decreee that dkim-rotate is 1.0. If you re a mail system administrator, your users are best served if you use something like dkim-rotate. The package is available in Debian stable, and supports Exim out of the box, but other MTAs should be easy to support too, via some simple ad-hoc scripting. Limitation of this approach Even with this key rotation approach, emails remain nonrepudiable for a short period after they re sent - typically, a few days. Someone who obtains a leaked email very promptly, and shows it to the journalist (for example) right away, can still convince the journalist. This is not great, but at least it doesn t apply to the vast bulk of your email archive. There are possible email protocol improvements which might help, but they re quite out of scope for this article.
Edited 2023-10-01 00:20 +01:00 to fix some grammar

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27 September 2023

Jonathan McDowell: onak 0.6.3 released

Yesterday I tagged a new version of onak, my OpenPGP compatible keyserver. I d spent a bit of time during DebConf doing some minor cleanups, in particular an annoying systemd socket activation issue I d been seeing. That turned out to be due completely failing to compile in the systemd support, even when it was detected. There was also a signature verification issue with certain Ed225519 signatures (thanks Antoine Beaupr for making me dig into that one), along with various code cleanups. I also worked on Stateless OpenPGP CLI support, which is something I talked about when I released 0.6.2. It isn t something that s suitable for release, but it is sufficient to allow running the OpenPGP interoperability test suite verification tests, which I m pleased to say all now pass. For the next release I m hoping the OpenPGP crypto refresh process will have completed, which at the very least will mean adding support for v6 packet types and fingerprints. The PostgreSQL DB backend could also use some love, and I might see if performance with SQLite3 has improved any. Anyway. Available locally or via GitHub.
0.6.3 - 26th September 2023
  • Fix systemd detection + socket activation
  • Add CMake checking for Berkeley DB
  • Minor improvements to keyd logging
  • Fix decoding of signature creation time
  • Relax version check on parsing signature + key packets
  • Improve HTML escaping
  • Handle failed database initialisation more gracefully
  • Fix bug with EDDSA signatures with top 8+ bits unset

21 September 2023

Jonathan Carter: DebConf23

I very, very nearly didn t make it to DebConf this year, I had a bad cold/flu for a few days before I left, and after a negative covid-19 test just minutes before my flight, I decided to take the plunge and travel. This is just everything in chronological order, more or less, it s the only way I could write it.

DebCamp I planned to spend DebCamp working on various issues. Very few of them actually got done, I spent the first few days in bed further recovering, took a covid-19 test when I arrived and after I felt better, and both were negative, so not sure what exactly was wrong with me, but between that and catching up with other Debian duties, I couldn t make any progress on catching up on the packaging work I wanted to do. I ll still post what I intended here, I ll try to take a few days to focus on these some time next month: Calamares / Debian Live stuff:
  • #980209 installation fails at the install boot loader phase
  • #1021156 calamares-settings-debian: Confusing/generic program names
  • #1037299 Install Debian -> Untrusted application launcher
  • #1037123 Minimal HD space required too small for some live images
  • #971003 Console auto-login doesn t work with sysvinit
At least Calamares has been trixiefied in testing, so there s that! Desktop stuff:
  • #1038660 please set a placeholder theme during development, different from any release
  • #1021816 breeze: Background image not shown any more
  • #956102 desktop-base: unwanted metadata within images
  • #605915 please mtheake it a non-native package
  • #681025 Put old themes in a new package named desktop-base-extra
  • #941642 desktop-base: split theme data files and desktop integrations in separate packages
The Egg theme that I want to develop for testing/unstable is based on Juliette Taka s Homeworld theme that was used for Bullseye. Egg, as in, something that hasn t quite hatched yet. Get it? (for #1038660) Debian Social:
  • Set up Lemmy instance
    • I started setting up a Lemmy instance before DebCamp, and meant to finish it.
  • Migrate PeerTube to new server
    • We got a new physical server for our PeerTube instance, we should have more space for growth and it would help us fix the streaming feature on our platform.
Loopy: I intended to get the loop for DebConf in good shape before I left, so that we can spend some time during DebCamp making some really nice content, unfortunately this went very tumbly, but at least we ended up with a loopy that kind of worked and wasn t too horrible. There s always another DebConf to try again, right?
So DebCamp as a usual DebCamp was pretty much a wash (fitting with all the rain we had?) for me, at least it gave me enough time to recover a bit for DebConf proper, and I had enough time left to catch up on some critical DPL duties and put together a few slides for the Bits from the DPL talk.

DebConf Bits From the DPL I had very, very little available time to prepare something for Bits fro the DPL, but I managed to put some slides together (available on my wiki page). I mostly covered:
  • A very quick introduction of myself (I ve done this so many times, it feels redundant giving my history every time), and some introduction on what it is that the DPL does. I declared my intent not to run for DPL again, and the reasoning behind it, and a few bits of information for people who may intend to stand for DPL next year.
  • The sentiment out there for the Debian 12 release (which has been very positive). How we include firmware by default now, and that we re saying goodbye to architectures both GNU/KFreeBSD and mipsel.
  • Debian Day and the 30th birthday party celebrations from local groups all over the world (and a reminder about the Local Groups BoF later in the week).
  • I looked forward to Debian 13 (trixie!), and how we re gaining riscv64 as a release architecture, as well as loongarch64, and that plans seem to be forming to fix 2k38 in Debian, and hopefully largely by the time the Trixie release comes by.
  • I made some comments about Enterprise Linux as people refer to the RHEL eco-system these days, how really bizarre some aspects of it is (like the kernel maintenance), and that some big vendors are choosing to support systems outside of that eco-system now (like CPanel now supporting Ubuntu too). I closed with the quote below from Ian Murdock, and assured the audience that if they want to go out and make money with Debian, they are more than welcome too.
Job Fair I walked through the hallway where the Job Fair was hosted, and enjoyed all the buzz. It s not always easy to get this right, but this year it was very active and energetic, I hope lots of people made some connections! Cheese & Wine Due to state laws and alcohol licenses, we couldn t consume alcohol from outside the state of Kerala in the common areas of the hotel (only in private rooms), so this wasn t quite as big or as fun as our usual C&W parties since we couldn t share as much from our individual countries and cultures, but we always knew that this was going to be the case for this DebConf, and it still ended up being alright. Day Trip I opted for the forest / waterfalls daytrip. It was really, really long with lots of time in the bus. I think our trip s organiser underestimated how long it would take between the points on the route (all in all it wasn t that far, but on a bus on a winding mountain road, it takes long). We left at 8:00 and only found our way back to the hotel around 23:30. Even though we arrived tired and hungry, we saw some beautiful scenery, animals and also met indigenous river people who talked about their struggles against being driven out of their place of living multiple times as government invests in new developments like dams and hydro power. Photos available in the DebConf23 public git repository. Losing a beloved Debian Developer during DebConf To our collective devastation, not everyone made it back from their day trips. Abraham Raji was out to the kayak day trip, and while swimming, got caught by a whirlpool from a drainage system. Even though all of us were properly exhausted and shocked in disbelief at this point, we had to stay up and make some tough decisions. Some initially felt that we had to cancel the rest of DebConf. We also had to figure out how to announce what happened asap both to the larger project and at DebConf in an official manner, while ensuring that due diligence took place and that the family is informed by the police first before making anything public. We ended up cancelling all the talks for the following day, with an address from the DPL in the morning to explain what had happened. Of all the things I ve ever had to do as DPL, this was by far the hardest. The day after that, talks were also cancelled for the morning so that we could attend his funeral. Dozens of DebConf attendees headed out by bus to go pay their final respects, many wearing the t-shirts that Abraham had designed for DebConf. A book of condolences was set up so that everyone who wished to could write a message on how they remembered him. The book will be kept by his family.
Today marks a week since his funeral, and I still feel very raw about it. And even though there was uncertainty whether DebConf should even continue after his death, in hindsight I m glad that everyone pushed forward. While we were all heart broken, it was also heart warming to see people care for each other in all of this. If anything, I think I needed more time at DebConf just to be in that warm aura of emotional support for just a bit longer. There are many people who I wanted to talk to who I barely even had a chance to see. Abraham, or Abru as he was called by some people (which I like because bru in Afrikaans is like bro in English, not sure if that s what it implied locally too) enjoyed artistic pursuits, but he was also passionate about knowledge transfer. He ran classes at DebConf both last year and this year (and I think at other local events too) where he taught people packaging via a quick course that he put together. His enthusiasm for Debian was contagious, a few of the people who he was mentoring came up to me and told me that they were going to see it through and become a DD in honor of him. I can t even remember how I reacted to that, my brain was already so worn out and stitching that together with the tragedy of what happened while at DebConf was just too much for me. I first met him in person last year in Kosovo, I already knew who he was, so I think we interacted during the online events the year before. He was just one of those people who showed so much promise, and I was curious to see what he d achieve in the future. Unfortunately, we was taken away from us too soon. Poetry Evening Later in the week we had the poetry evening. This was the first time I had the courage to recite something. I read Ithaka by C.P. Cavafy (translated by Edmund Keely). The first time I heard about this poem was in an interview with Julian Assange s wife, where she mentioned that he really loves this poem, and it caught my attention because I really like the Weezer song Return to Ithaka and always wondered what it was about, so needless to say, that was another rabbit hole at some point. Group Photo Our DebConf photographer organised another group photo for this event, links to high-res versions available on Aigar s website.
BoFs I didn t attend nearly as many talks this DebConf as I would ve liked (fortunately I can catch up on video, should be released soon), but I did make it to a few BoFs. In the Local Groups BoF, representatives from various local teams were present who introduced themselves and explained what they were doing. From memory (sorry if I left someone out), we had people from Belgium, Brazil, Taiwan and South Africa. We talked about types of events a local group could do (BSPs, Mini DC, sprints, Debian Day, etc. How to help local groups get started, booth kits for conferences, and setting up some form of calendar that lists important Debian events in a way that makes it easier for people to plan and co-ordinate. There s a mailing list for co-ordination of local groups, and the irc channel is -localgroups on oftc.
If you got one of these Cheese & Wine bags from DebConf, that s from the South African local group!
In the BoF, we discussed the hosting service, where Debian pays for VMs hosted for projects by individual DDs on The idea is that we start some form of census that monitors the services, whether they re still in use, whether the system is up to date, whether someone still cares for it, etc. We had some discussion about where the lines of responsibility are drawn, and we can probably make things a little bit more clear in the documentation. We also want to offer more in terms of backups and monitoring (currently DDs do get 500GB from that could be used for backups of their services though). The intention is also to deploy some form of configuration management for some essentials across the hosts. We should also look at getting some sponsored hosting for this. In the Debian Social BoF, we discussed some services that need work / expansion. In particular, Matrix keeps growing at an increased rate as more users use it and more channels are bridged, so it will likely move to its own host with big disks soon. We might replace Pleroma with a fork called Akkoma, this will need some more home work and checking whether it s even feasible. Some services haven t really been used (like Writefreely and Plume), and it might be time to retire them. We might just have to help one or two users migrate some of their posts away if we do retire them. Mjolner seems to do a fine job at spam blocking, we haven t had any notable incidents yet. WordPress now has improved fediverse support, it s unclear whether it works on a multi-site instance yet, I ll test it at some point soon and report back. For upcoming services, we are implementing Lemmy and probably also Mobilizon. A request was made that we also look into Loomio. More Information Overload There s so much that happens at DebConf, it s tough to take it all in, and also, to find time to write about all of it, but I ll mention a few more things that are certainly worth of note. During DebConf, we had some people from the Kite Linux team over. KITE supplies the ICT needs for the primary and secondary schools in the province of Kerala, where they all use Linux. They decided to switch all of these to Debian. There was an ad-hoc BoF where locals were listening and fielding questions that the Kite Linux team had. It was great seeing all the energy and enthusiasm behind this effort, I hope someone will properly blog about this! I learned about the VGLUG Foundation, who are doing a tremendous job at promoting GNU/Linux in the country. They are also training up 50 people a year to be able to provide tech support for Debian. I came across the booth for Mostly Harmless, they liberate old hardware by installing free firmware on there. It was nice seeing all the devices out there that could be liberated, and how it can breathe new life into old harware.
Some hopefully harmless soldering.
Overall, the community and their activities in India are very impressive, and I wish I had more time to get to know everyone better. Food Oh yes, one more thing. The food was great. I tasted more different kinds of curry than I ever did in my whole life up to this point. The lunch on banana leaves was interesting, and also learning how to eat this food properly by hand (thanks to the locals who insisted on teaching me!), it was a fruitful experience? This might catch on at home too less dishes to take care of! Special thanks to the DebConf23 Team I think this may have been one of the toughest DebConfs to organise yet, and I don t think many people outside of the DebConf team knows about all the challenges and adversity this team has faced in organising it. Even just getting to the previous DebConf in Kosovo was a long and tedious and somewhat risky process. Through it all, they were absolute pro s. Not once did I see them get angry or yell at each other, whenever a problem came up, they just dealt with it. They did a really stellar job and I did make a point of telling them on the last day that everyone appreciated all the work that they did. Back to my nest I bought Dax a ball back from India, he seems to have forgiven me for not taking him along.
I ll probably take a few days soon to focus a bit on my bugs and catch up on my original DebCamp goals. If you made it this far, thanks for reading! And thanks to everyone for being such fantastic people.

15 September 2023

John Goerzen: How Gapped is Your Air?

Sometimes we want better-than-firewall security for things. For instance:
  1. An industrial control system for a municipal water-treatment plant should never have data come in or out
  2. Or, a variant of the industrial control system: it should only permit telemetry and monitoring data out, and nothing else in or out
  3. A system dedicated to keeping your GPG private keys secure should only have material to sign (or decrypt) come in, and signatures (or decrypted data) go out
  4. A system keeping your tax records should normally only have new records go in, but may on occasion have data go out (eg, to print a copy of an old record)
In this article, I ll talk about the high side (the high-security or high-sensitivity systems) and the low side (the lower-sensitivity or general-purpose systems). For the sake of simplicity, I ll assume the high side is a single machine, but it could as well be a whole network. Let s focus on examples 3 and 4 to make things simpler. Let s consider the primary concern to be data exfiltration (someone stealing your data), with a secondary concern of data integrity (somebody modifying or destroying your data). You might think the safest possible approach is Airgapped that is, there is literal no physical network connection to the machine at all. This help! But then, the problem becomes: how do we deal with the inevitable need to legitimately get things on or off of the system? As I wrote in Dead USB Drives Are Fine: Building a Reliable Sneakernet, by using tools such as NNCP, you can certainly create a sneakernet : using USB drives as transport. While this is a very secure setup, as with most things in security, it s less than perfect. The Wikipedia airgap article discusses some ways airgapped machines can still be exploited. It mentions that security holes relating to removable media have been exploited in the past. There are also other ways to get data out; for instance, Debian ships with gensio and minimodem, both of which can transfer data acoustically. But let s back up and think about why we think of airgapped machines as so much more secure, and what the failure modes of other approaches might be.

What about firewalls? You could very easily set up high-side machine that is on a network, but is restricted to only one outbound TCP port. There could be a local firewall, and perhaps also a special port on an external firewall that implements the same restrictions. A variant on this approach would be two computers connected directly by a crossover cable, though this doesn t necessarily imply being more secure. Of course, the concern about a local firewall is that it could potentially be compromised. An external firewall might too; for instance, if your credentials to it were on a machine that got compromised. This kind of dual compromise may be unlikely, but it is possible. We can also think about the complexity in a network stack and firewall configuration, and think that there may be various opportunities to have things misconfigured or buggy in a system of that complexity. Another consideration is that data could be sent at any time, potentially making it harder to detect. On the other hand, network monitoring tools are commonplace. On the other hand, it is convenient and cheap. I use a system along those lines to do my backups. Data is sent, gpg-encrypted and then encrypted again at the NNCP layer, to the backup server. The NNCP process on the backup server runs as an untrusted user, and dumps the gpg-encrypted files to a secure location that is then processed by a cron job using Filespooler. The backup server is on a dedicated firewall port, with a dedicated subnet. The only ports allowed out are for NNCP and NTP, and offsite backups. There is no default gateway. Not even DNS is permitted out (the firewall does the appropriate redirection). There is one pinhole allowed out, where a subset of the backup data is sent offsite. I initially used USB drives as transport, and it had no network connection at all. But there were disadvantages to doing this for backups particularly that I d have no backups for as long as I d forget to move the drives. The backup system also would have clock drift, and the offsite backup picture was more challenging. (The clock drift was a problem because I use 2FA on the system; a password, plus a TOTP generated by a Yubikey) This is pretty good security, I d think. What are the weak spots? Well, if there were somehow a bug in the NNCP client, and the remote NNCP were compromised, that could lead to a compromise of the NNCP account. But this itself would accomplish little; some other vulnerability would have to be exploited on the backup server, because the NNCP account can t see plaintext data at all. I use borgbackup to send a subset of backup data offsite over ssh. borgbackup has to run as root to be able to access all the files, but the ssh it calls runs as a separate user. A ssh vulnerability is therefore unlikely to cause much damage. If, somehow, the remote offsite system were compromised and it was able to exploit a security issue in the local borgbackup, that would be a problem. But that sounds like a remote possibility. borgbackup itself can t even be used over a sneakernet since it is not asynchronous. A more secure solution would probably be using something like dar over NNCP. This would eliminate the ssh installation entirely, and allow a complete isolation between the data-access and the communication stacks, and notably not require bidirectional communication. Logic separation matters too. My Roundup of Data Backup and Archiving Tools may be helpful here. Other attack vectors could be a vulnerability in the kernel s networking stack, local root exploits that could be combined with exploiting NNCP or borgbackup to gain root, or local misconfiguration that makes the sandboxes around NNCP and borgbackup less secure. Because this system is in my basement in a utility closet with no chairs and no good place for a console, I normally manage it via a serial console. While it s a dedicated line between the system and another machine, if the other machine is compromised or an adversary gets access to the physical line, credentials (and perhaps even data) could leak, albeit slowly. But we can do much better with serial lines. Let s take a look.

Serial lines Some of us remember RS-232 serial lines and their once-ubiquitous DB-9 connectors. Traditionally, their speed maxxed out at 115.2Kbps. Serial lines have the benefit that they can be a direct application-to-application link. In my backup example above, a serial line could directly link the NNCP daemon on one system with the NNCP caller on another, with no firewall or anything else necessary. It is simply up to those programs to open the serial device appropriately. This isn t perfect, however. Unlike TCP over Ethernet, a serial line has no inherent error checking. Modern programs such as NNCP and ssh assume that a lower layer is making the link completely clean and error-free for them, and will interpret any corruption as an attempt to tamper and sever the connection. However, there is a solution to that: gensio. In my page Using gensio and ser2net, I discuss how to run NNCP and ssh over gensio. gensio is a generic framework that can add framing, error checking, and retransmit to an unreliable link such as a serial port. It can also add encryption and authentication using TLS, which could be particularly useful for applications that aren t already doing that themselves. More traditional solutions for serial communications have their own built-in error correction. For instance, UUCP and Kermit both were designed in an era of noisy serial lines and might be an excellent fit for some use cases. The ZModem protocol also might be, though it offers somewhat less flexibility and automation than Kermit. I have found that certain USB-to-serial adapters by Gearmo will actually run at up to 2Mbps on a serial line! Look for the ones on their spec pages with a FTDI chipset rated at 920Kbps. It turns out they can successfully be driven faster, especially if gensio s relpkt is used. I ve personally verified 2Mbps operation (Linux port speed 2000000) on Gearmo s USA-FTDI2X and the USA-FTDI4X. (I haven t seen any single-port options from Gearmo with the 920Kbps chipset, but they may exist). Still, even at 2Mbps, speed may well be a limiting factor with some applications. If what you need is a console and some textual or batch data, it s probably fine. If you are sending 500GB backup files, you might look for something else. In theory, this USB to RS-422 adapter should work at 10Mbps, but I haven t tried it. But if the speed works, running a dedicated application over a serial link could be a nice and fairly secure option. One of the benefits of the airgapped approach is that data never leaves unless you are physically aware of transporting a USB stick. Of course, you may not be physically aware of what is ON that stick in the event of a compromise. This could easily be solved with a serial approach by, say, only plugging in the cable when you have data to transfer.

Data diodes A traditional diode lets electrical current flow in only one direction. A data diode is the same concept, but for data: a hardware device that allows data to flow in only one direction. This could be useful, for instance, in the tax records system that should only receive data, or the industrial system that should only send it. Wikipedia claims that the simplest kind of data diode is a fiber link with transceivers connected in only one direction. I think you could go one simpler: a serial cable with only ground and TX connected at one end, wired to ground and RX at the other. (I haven t tried this.) This approach does have some challenges:
  • Many existing protocols assume a bidirectional link and won t be usable
  • There is a challenge of confirming data was successfully received. For a situation like telemetry, maybe it doesn t matter; another observation will come along in a minute. But for sending important documents, one wants to make sure they were properly received.
In some cases, the solution might be simple. For instance, with telemetry, just writing out data down the serial port in a simple format may be enough. For sending files, various mitigations, such as sending them multiple times, etc., might help. You might also look into FEC-supporting infrastructure such as blkar and flute, but these don t provide an absolute guarantee. There is no perfect solution to knowing when a file has been successfully received if the data communication is entirely one-way.

Audio transport I hinted above that minimodem and gensio both are software audio modems. That is, you could literally use speakers and microphones, or alternatively audio cables, as a means of getting data into or out of these systems. This is pretty limited; it is 1200bps, and often half-duplex, and could literally be disrupted by barking dogs in some setups. But hey, it s an option.

Airgapped with USB transport This is the scenario I began with, and named some of the possible pitfalls above as well. In addition to those, note also that USB drives aren t necessarily known for their error-free longevity. Be prepared for failure.

Concluding thoughts I wanted to lay out a few things in this post. First, that simply being airgapped is generally a step forward in security, but is not perfect. Secondly, that both physical and logical separation matter. And finally, that while tools like NNCP can make airgapped-with-USB-drive-transport a doable reality, there are also alternatives worth considering especially serial ports, firewalled hard-wired Ethernet, data diodes, and so forth. I think serial links, in particular, have been largely forgotten these days. Note: This article also appears on my website, where it may be periodically updated.

12 September 2023

Valhalla's Things: How I Keep my Life in Git

Posted on September 12, 2023
git secret_cabal greet
After watching My life in git, after subversion, after CVS. from DebConf, I ve realized it s been a while since I talked about the way I keep everything1 I do in git, and I don t think I ve ever done it online, so it looked like a good time for a blog post. Beyond git itself (of course), I use a few git-related programs:
  • myrepos (also known as mr) to manage multiple git repositories with one command;
  • vcsh to make it easy to keep dot-files under git;
  • git annex to store media files (anything that is big and will not change);
  • etckeeper to keep an history of the /etc directory;
  • gitolite and cgit to host my git repositories;
and some programs that don t use git directly, but easily interact with it:
  • ansible to keep track of the system configuration of all machines;
  • lesana as a project tracker and journal and to inventory the things made of atoms that are hard 2 to store in git.
All of these programs are installed from Debian packages, on stable (plus rarely backports) or testing, depending on the machine. I m also grateful to the vcs-home people, who wrote most of the tools I use, and sometimes hang around their IRC channel. And now, on to what I m actually doing. With the git repositories I ve decided to err for too much granularity rather than too little3, so of course each project has its own repository, and so do different kinds of media files, dot-files that are related to different programs etc. Most of the repositories are hosted on two gitolite servers: one runs on the home server, for stuff that should remain private, and the other one is on my VPS for things that are public (or may become public in the future), and also has a web interface with cgit. Of course things where I m collaborating with other people are sometimes hosted elsewhere, mostly on salsa, sourcehut or on $DAYJOB related gitlab instances. The .mr directory is where everything is managed: I don t have a single .mrconfig file but a few different ones, that in turn load all files in a directory with the same name:
  • for the media file annexes and inventories (split into different files, so that computers with little disk space can only get the inventories);
  • for stuff that should only go on my own personal machine, not on shared ones;
  • for the actual projects, with different files for the kinds of projects (software, docs, packaging, crafts, etc.);
  • with all of the vcsh repositories, including the one that tracks the mr files (I ll talk about the circular dependency later);
  • for repositories that are related to $DAYJOB.
Then there are the files in the .mr/machines directory, each one of which has the list of repositories that should be on every specific machine, including a generic workstation, but also specific machines such as e.g. the media center which has a custom set of repositories. The dot files from my home directory are kept in vcsh, so that it s easy to split them out into different repositories, and I m mostly used the simplest configuration described in the 30 Second How-to in its homepage; vcsh gives some commands to work on all vcsh repositories at the same time, but most of the time I work on a single repository, and use mr to act on more than one repo. The media collections are also pretty straightforward git-annex repositories, one for each kind of media (music, movies and other videos, e-books, pictures, etc.) and I don t use any auto-syncing features but simply copy and move files around between clones with the git annex copy, git annex move and git annex get commands. There isn t much to say about the project repositories (plain git), and I think that the way I use my own program lesana for inventories and project tracking is worth an article of its own, here I ll just say that the file format used has been designed (of course) to work nicely with git. On every machine I install etckeeper so that there is a history of the changes in the /etc directory, but that s only a local repository, not stored anywhere else, and is used mostly in case something breaks with an update or in similar situation. The authoritative source for the configuration of each machine is an ansible playbook (of course saved in git) which can be used to fully reconfigure the machine from a bare Debian installation. When such a reconfiguration from scratch happens, it will be in two stages: first a run of ansible does the system-wide configuration (including installing packages, creating users etc.), and then I login on the machine and run mr to set up my own home. Of course there is a chicken-and-egg problem in that I need the mr configuration to know where to get the mr configuration, and that is solved by having setup two vcsh repositories from an old tarball export: the one with the ssh configuration to access the repositories and the one with the mr files. So, after a machine has been configured with ansible what I ll actually do is to login, use vcsh pull to update those two repositories and then run mr to checkout everything else. And that s it, if you have questions on something feel free to ask me on the fediverse or via email (contacts are in the about page) Update (2023-09-12 17:00ish): The ~/.mr directory is not special for mr, it s just what I use and then I always run mr -c ~/.mr/some/suitable/, with the actual file being different whether I m registering a new repo or checking out / updating them. I could include some appropriate ~/.mr/machines/ in ~/.mrconfig, but I ve never bothered to do so, since it wouldn t cover all usecases anyway. Thanks to the person on #vcs-home@OFTC who asked me the question :)

  1. At least, everything that I made that is made of bits, and a diary and/or inventory of the things made of atoms.
  2. until we get a working replicator, I guess :D
  3. in time I ve consolidated a bit some of the repositories, e.g. merging the repositories for music from different sources (CD rips, legal downloads, etc.) into a single repository, but that only happened a few times, and usually I m fine with the excess of granularity.

8 September 2023

Reproducible Builds: Reproducible Builds in August 2023

Welcome to the August 2023 report from the Reproducible Builds project! In these reports we outline the most important things that we have been up to over the past month. As a quick recap, whilst anyone may inspect the source code of free software for malicious flaws, almost all software is distributed to end users as pre-compiled binaries. The motivation behind the reproducible builds effort is to ensure no flaws have been introduced during this compilation process by promising identical results are always generated from a given source, thus allowing multiple third-parties to come to a consensus on whether a build was compromised. If you are interested in contributing to the project, please visit our Contribute page on our website.

Rust serialisation library moving to precompiled binaries Bleeping Computer reported that Serde, a popular Rust serialization framework, had decided to ship its serde_derive macro as a precompiled binary. As Ax Sharma writes:
The move has generated a fair amount of push back among developers who worry about its future legal and technical implications, along with a potential for supply chain attacks, should the maintainer account publishing these binaries be compromised.
After intensive discussions, use of the precompiled binary was phased out.

Reproducible builds, the first ten years On August 4th, Holger Levsen gave a talk at BornHack 2023 on the Danish island of Funen titled Reproducible Builds, the first ten years which promised to contain:
[ ] an overview about reproducible builds, the past, the presence and the future. How it started with a small [meeting] at DebConf13 (and before), how it grew from being a Debian effort to something many projects work on together, until in 2021 it was mentioned in an executive order of the president of the United States. (HTML slides)
Holger repeated the talk later in the month at Chaos Communication Camp 2023 in Zehdenick, Germany: A video of the talk is available online, as are the HTML slides.

Reproducible Builds Summit Just another reminder that our upcoming Reproducible Builds Summit is set to take place from October 31st November 2nd 2023 in Hamburg, Germany. 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. If you re interested in joining us this year, please make sure to read the event page, the news item, or the invitation email that Mattia Rizzolo sent out, which have more details about the event and location. We are also still looking for sponsors to support the event, so do reach out to the organizing team if you are able to help. (Also of note that PackagingCon 2023 is taking place in Berlin just before our summit, and their schedule has just been published.)

Vagrant Cascadian on the Sustain podcast Vagrant Cascadian was interviewed on the SustainOSS podcast on reproducible builds:
Vagrant walks us through his role in the project where the aim is to ensure identical results in software builds across various machines and times, enhancing software security and creating a seamless developer experience. Discover how this mission, supported by the Software Freedom Conservancy and a broad community, is changing the face of Linux distros, Arch Linux, openSUSE, and F-Droid. They also explore the challenges of managing random elements in software, and Vagrant s vision to make reproducible builds a standard best practice that will ideally become automatic for users. Vagrant shares his work in progress and their commitment to the last mile problem.
The episode is available to listen (or download) from the Sustain podcast website. As it happens, the episode was recorded at FOSSY 2023, and the video of Vagrant s talk from this conference (Breaking the Chains of Trusting Trust is now available on It was also announced that Vagrant Cascadian will be presenting at the Open Source Firmware Conference in October on the topic of Reproducible Builds All The Way Down.

On our mailing list Carles Pina i Estany wrote to our mailing list during August with an interesting question concerning the practical steps to reproduce the hello-traditional package from Debian. The entire thread can be viewed from the archive page, as can Vagrant Cascadian s reply.

Website updates Rahul Bajaj updated our website to add a series of environment variations related to reproducible builds [ ], Russ Cox added the Go programming language to our projects page [ ] and Vagrant Cascadian fixed a number of broken links and typos around the website [ ][ ][ ].

Software development In diffoscope development this month, versions 247, 248 and 249 were uploaded to Debian unstable by Chris Lamb, who also added documentation for the new specialize_as method and expanding the documentation of the existing specialize as well [ ]. In addition, Fay Stegerman added specialize_as and used it to optimise .smali comparisons when decompiling Android .apk files [ ], Felix Yan and Mattia Rizzolo corrected some typos in code comments [ , ], Greg Chabala merged the RUN commands into single layer in the package s Dockerfile [ ] thus greatly reducing the final image size. Lastly, Roland Clobus updated tool descriptions to mark that the xb-tool has moved package within Debian [ ].
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, Vagrant Cascadian updated the packaging to be compatible with Tox version 4. This was originally filed as Debian bug #1042918 and Holger Levsen uploaded this to change to Debian unstable as version 0.7.26 [ ].

Distribution work In Debian, 28 reviews of Debian packages were added, 14 were updated and 13 were removed this month adding to our knowledge about identified issues. A number of issue types were added, including Chris Lamb adding a new timestamp_in_documentation_using_sphinx_zzzeeksphinx_theme toolchain issue.
In August, F-Droid added 25 new reproducible apps and saw 2 existing apps switch to reproducible builds, making 191 apps in total that are published with Reproducible Builds and using the upstream developer s signature. [ ]
Bernhard M. Wiedemann published another monthly report about reproducibility within openSUSE.

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:

Testing framework The Reproducible Builds project operates a comprehensive testing framework (available at in order to check packages and other artifacts for reproducibility. In August, a number of changes were made by Holger Levsen:
  • Debian-related changes:
    • Disable Debian live image creation jobs until an OpenQA credential problem has been fixed. [ ]
    • Run our maintenance scripts every 3 hours instead of every 2. [ ]
    • Export data for unstable to the reproducible-tracker.json data file. [ ]
    • Stop varying the build path, we want reproducible builds. [ ]
    • Temporarily stop updating the pbuilder.tgz for Debian unstable due to #1050784. [ ][ ]
    • Correctly document that we are not variying usrmerge. [ ][ ]
    • Mark two armhf nodes (wbq0 and jtx1a) as down; investigation is needed. [ ]
  • Misc:
    • Force reconfiguration of all Jenkins jobs, due to the recent rise of zombie processes. [ ]
    • In the node health checks, also try to restart failed ntpsec, postfix and vnstat services. [ ][ ][ ]
  • System health checks:
    • Detect Debian live build failures due to missing credentials. [ ][ ]
    • Ignore specific types of known zombie processes. [ ][ ]
In addition, Vagrant Cascadian updated the scripts to use a predictable build path that is consistent with the one used on [ ][ ]

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:

30 August 2023

Dirk Eddelbuettel: RcppArmadillo on CRAN: New Upstream Bugfix

armadillo image Armadillo is a powerful and expressive C++ template library for linear algebra and scientific computing. It aims towards a good balance between speed and ease of use, has a syntax deliberately close to Matlab, and is useful for algorithm development directly in C++, or quick conversion of research code into production environments. RcppArmadillo integrates this library with the R environment and language and is widely used by (currently) 1092 other packages on CRAN, downloaded 30.3 million times (per the partial logs from the cloud mirrors of CRAN), and the CSDA paper (preprint / vignette) by Conrad and myself has been cited 549 times according to Google Scholar. This release brings bugfix upstream release 12.6.3. We skipped 12.6.2 at CRAN (as discussed in the previous release notes) as it only affected Armadillo-internal random-number generation (RNG). As we default to supplying the RNGs from R, this did not affect RcppArmadillo. The bug fixes in 12.6.3 are for csv reading which too will most likely be done by R tools for R users, but given two minor bugfix releases an update was in order. I ran the full reverse-depenency check against the now more than 1000 packages overnight: no issues. armadillo processing CRAN processed the package fully automatically as it has no issues, and nothing popped up in reverse-dependency checking. The set of changes for the last two RcppArmadillo releases follows.

Changes in RcppArmadillo version (2023-08-28)
  • Upgraded to Armadillo release 12.6.3 (Cortisol Retox)
    • Fix for corner-case in loading CSV files with headers
    • For consistent file handling, all .load() functions now open text files in binary mode

Changes in RcppArmadillo version (2023-08-08)
  • Upgraded to Armadillo release 12.6.2 (Cortisol Retox)
    • use thread-safe Mersenne Twister as the default RNG on all platforms
    • use unique RNG seed for each thread within multi-threaded execution (such as OpenMP)
    • explicitly document arma_rng::set_seed() and arma_rng::set_seed_random()
  • None of the changes above affect R use as RcppArmadillo connects the RNGs used by R to Armadillo

Courtesy of my CRANberries, there is a diffstat report relative to previous release. More detailed information is on the RcppArmadillo page. Questions, comments etc should go to the rcpp-devel mailing list off the Rcpp R-Forge page. If you like this or other open-source work I do, you can sponsor me at GitHub.

This post by Dirk Eddelbuettel originated on his Thinking inside the box blog. Please report excessive re-aggregation in third-party for-profit settings.