Search Results: "steve"

14 March 2024

Matthew Garrett: Digital forgeries are hard

Closing arguments in the trial between various people and Craig Wright over whether he's Satoshi Nakamoto are wrapping up today, amongst a bewildering array of presented evidence. But one utterly astonishing aspect of this lawsuit is that expert witnesses for both sides agreed that much of the digital evidence provided by Craig Wright was unreliable in one way or another, generally including indications that it wasn't produced at the point in time it claimed to be. And it's fascinating reading through the subtle (and, in some cases, not so subtle) ways that that's revealed.

One of the pieces of evidence entered is screenshots of data from Mind Your Own Business, a business management product that's been around for some time. Craig Wright relied on screenshots of various entries from this product to support his claims around having controlled meaningful number of bitcoin before he was publicly linked to being Satoshi. If these were authentic then they'd be strong evidence linking him to the mining of coins before Bitcoin's public availability. Unfortunately the screenshots themselves weren't contemporary - the metadata shows them being created in 2020. This wouldn't fundamentally be a problem (it's entirely reasonable to create new screenshots of old material), as long as it's possible to establish that the material shown in the screenshots was created at that point. Sadly, well.

One part of the disclosed information was an email that contained a zip file that contained a raw database in the format used by MYOB. Importing that into the tool allowed an audit record to be extracted - this record showed that the relevant entries had been added to the database in 2020, shortly before the screenshots were created. This was, obviously, not strong evidence that Craig had held Bitcoin in 2009. This evidence was reported, and was responded to with a couple of additional databases that had an audit trail that was consistent with the dates in the records in question. Well, partially. The audit record included session data, showing an administrator logging into the data base in 2011 and then, uh, logging out in 2023, which is rather more consistent with someone changing their system clock to 2011 to create an entry, and switching it back to present day before logging out. In addition, the audit log included fields that didn't exist in versions of the product released before 2016, strongly suggesting that the entries dated 2009-2011 were created in software released after 2016. And even worse, the order of insertions into the database didn't line up with calendar time - an entry dated before another entry may appear in the database afterwards, indicating that it was created later. But even more obvious? The database schema used for these old entries corresponded to a version of the software released in 2023.

This is all consistent with the idea that these records were created after the fact and backdated to 2009-2011, and that after this evidence was made available further evidence was created and backdated to obfuscate that. In an unusual turn of events, during the trial Craig Wright introduced further evidence in the form of a chain of emails to his former lawyers that indicated he had provided them with login details to his MYOB instance in 2019 - before the metadata associated with the screenshots. The implication isn't entirely clear, but it suggests that either they had an opportunity to examine this data before the metadata suggests it was created, or that they faked the data? So, well, the obvious thing happened, and his former lawyers were asked whether they received these emails. The chain consisted of three emails, two of which they confirmed they'd received. And they received a third email in the chain, but it was different to the one entered in evidence. And, uh, weirdly, they'd received a copy of the email that was submitted - but they'd received it a few days earlier. In 2024.

And again, the forensic evidence is helpful here! It turns out that the email client used associates a timestamp with any attachments, which in this case included an image in the email footer - and the mysterious time travelling email had a timestamp in 2024, not 2019. This was created by the client, so was consistent with the email having been sent in 2024, not being sent in 2019 and somehow getting stuck somewhere before delivery. The date header indicates 2019, as do encoded timestamps in the MIME headers - consistent with the mail being sent by a computer with the clock set to 2019.

But there's a very weird difference between the copy of the email that was submitted in evidence and the copy that was located afterwards! The first included a header inserted by gmail that included a 2019 timestamp, while the latter had a 2024 timestamp. Is there a way to determine which of these could be the truth? It turns out there is! The format of that header changed in 2022, and the version in the email is the new version. The version with the 2019 timestamp is anachronistic - the format simply doesn't match the header that gmail would have introduced in 2019, suggesting that an email sent in 2022 or later was modified to include a timestamp of 2019.

This is by no means the only indication that Craig Wright's evidence may be misleading (there's the whole argument that the Bitcoin white paper was written in LaTeX when general consensus is that it's written in OpenOffice, given that's what the metadata claims), but it's a lovely example of a more general issue.

Our technology chains are complicated. So many moving parts end up influencing the content of the data we generate, and those parts develop over time. It's fantastically difficult to generate an artifact now that precisely corresponds to how it would look in the past, even if we go to the effort of installing an old OS on an old PC and setting the clock appropriately (are you sure you're going to be able to mimic an entirely period appropriate patch level?). Even the version of the font you use in a document may indicate it's anachronistic. I'm pretty good at computers and I no longer have any belief I could fake an old document.

(References: this Dropbox, under "Expert reports", "Patrick Madden". Initial MYOB data is in "Appendix PM7", further analysis is in "Appendix PM42", email analysis is "Sixth Expert Report of Mr Patrick Madden")

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22 January 2024

Paul Tagliamonte: Writing a simulator to check phased array beamforming

Interested in future updates? Follow me on mastodon at @paul@soylent.green. Posts about hz.tools will be tagged #hztools.

If you're on the Fediverse, I'd very much appreciate boosts on my toot!
While working on hz.tools, 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
.iter()
.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()))
.collect();
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
.iter()
.zip(observed_phases.iter())
.map( (beamformed, observed)  observed * beamformed)
.reduce( acc, el  acc + el)
.unwrap()
.abs();
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.

31 December 2023

Chris Lamb: Favourites of 2023

This post should have marked the beginning of my yearly roundups of the favourite books and movies I read and watched in 2023. However, due to coming down with a nasty bout of flu recently and other sundry commitments, I wasn't able to undertake writing the necessary four or five blog posts In lieu of this, however, I will simply present my (unordered and unadorned) highlights for now. Do get in touch if this (or any of my previous posts) have spurred you into picking something up yourself

Books

Peter Watts: Blindsight (2006) Reymer Banham: Los Angeles: The Architecture of Four Ecologies (2006) Joanne McNeil: Lurking: How a Person Became a User (2020) J. L. Carr: A Month in the Country (1980) Hilary Mantel: A Memoir of My Former Self: A Life in Writing (2023) Adam Higginbotham: Midnight in Chernobyl (2019) Tony Judt: Postwar: A History of Europe Since 1945 (2005) Tony Judt: Reappraisals: Reflections on the Forgotten Twentieth Century (2008) Peter Apps: Show Me the Bodies: How We Let Grenfell Happen (2021) Joan Didion: Slouching Towards Bethlehem (1968)Erik Larson: The Devil in the White City (2003)

Films Recent releases

Unenjoyable experiences included Alejandro G mez Monteverde's Sound of Freedom (2023), Alex Garland's Men (2022) and Steven Spielberg's The Fabelmans (2022).
Older releases (Films released before 2022, and not including rewatches from previous years.) Distinctly unenjoyable watches included Ocean's Eleven (1960), El Topo (1970), L olo (1992), Hotel Mumbai (2018), Bulworth (1998) and and The Big Red One (1980).

6 December 2023

Reproducible Builds: Reproducible Builds in November 2023

Welcome to the November 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 rather rapid 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 (more).

Reproducible Builds Summit 2023 Between October 31st and November 2nd, we held our seventh Reproducible Builds Summit in Hamburg, Germany! Amazingly, the agenda and all notes from all sessions are all online many thanks to everyone who wrote notes from the sessions. As a followup on one idea, started at the summit, Alexander Couzens and Holger Levsen started work on a cache (or tailored front-end) for the snapshot.debian.org service. The general idea is that, when rebuilding Debian, you do not actually need the whole ~140TB of data from snapshot.debian.org; rather, only a very small subset of the packages are ever used for for building. It turns out, for amd64, arm64, armhf, i386, ppc64el, riscv64 and s390 for Debian trixie, unstable and experimental, this is only around 500GB ie. less than 1%. Although the new service not yet ready for usage, it has already provided a promising outlook in this regard. More information is available on https://rebuilder-snapshot.debian.net and we hope that this service becomes usable in the coming weeks. The adjacent picture shows a sticky note authored by Jan-Benedict Glaw at the summit in Hamburg, confirming Holger Levsen s theory that rebuilding all Debian packages needs a very small subset of packages, the text states that 69,200 packages (in Debian sid) list 24,850 packages in their .buildinfo files, in 8,0200 variations. This little piece of paper was the beginning of rebuilder-snapshot and is a direct outcome of the summit! The Reproducible Builds team would like to thank our event sponsors who include Mullvad VPN, openSUSE, Debian, Software Freedom Conservancy, Allotropia and Aspiration Tech.

Beyond Trusting FOSS presentation at SeaGL On November 4th, Vagrant Cascadian presented Beyond Trusting FOSS at SeaGL in Seattle, WA in the United States. Founded in 2013, SeaGL is a free, grassroots technical summit dedicated to spreading awareness and knowledge about free source software, hardware and culture. The summary of Vagrant s talk mentions that it will:
[ ] introduce the concepts of Reproducible Builds, including best practices for developing and releasing software, the tools available to help diagnose issues, and touch on progress towards solving decades-old deeply pervasive fundamental security issues Learn how to verify and demonstrate trust, rather than simply hoping everything is OK!
Germane to the contents of the talk, the slides for Vagrant s talk can be built reproducibly, resulting in a PDF with a SHA1 of cfde2f8a0b7e6ec9b85377eeac0661d728b70f34 when built on Debian bookworm and c21fab273232c550ce822c4b0d9988e6c49aa2c3 on Debian sid at the time of writing.

Human Factors in Software Supply Chain Security Marcel Fourn , Dominik Wermke, Sascha Fahl and Yasemin Acar have published an article in a Special Issue of the IEEE s Security & Privacy magazine. Entitled A Viewpoint on Human Factors in Software Supply Chain Security: A Research Agenda, the paper justifies the need for reproducible builds to reach developers and end-users specifically, and furthermore points out some under-researched topics that we have seen mentioned in interviews. An author pre-print of the article is available in PDF form.

Community updates On our mailing list this month:

openSUSE updates Bernhard M. Wiedemann has created a wiki page outlining an proposal to create a general-purpose Linux distribution which consists of 100% bit-reproducible packages albeit minus the embedded signature within RPM files. It would be based on openSUSE Tumbleweed or, if available, its Slowroll-variant. In addition, Bernhard posted another monthly update for his work elsewhere in openSUSE.

Ubuntu Launchpad now supports .buildinfo files Back in 2017, Steve Langasek filed a bug against Ubuntu s Launchpad code hosting platform to report that .changes files (artifacts of building Ubuntu and Debian packages) reference .buildinfo files that aren t actually exposed by Launchpad itself. This was causing issues when attempting to process .changes files with tools such as Lintian. However, it was noticed last month that, in early August of this year, Simon Quigley had resolved this issue, and .buildinfo files are now available from the Launchpad system.

PHP reproducibility updates There have been two updates from the PHP programming language this month. Firstly, the widely-deployed PHPUnit framework for the PHP programming language have recently released version 10.5.0, which introduces the inclusion of a composer.lock file, ensuring total reproducibility of the shipped binary file. Further details and the discussion that went into their particular implementation can be found on the associated GitHub pull request. In addition, the presentation Leveraging Nix in the PHP ecosystem has been given in late October at the PHP International Conference in Munich by Pol Dellaiera. While the video replay is not yet available, the (reproducible) presentation slides and speaker notes are available.

diffoscope changes 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, including:
  • Improving DOS/MBR extraction by adding support for 7z. [ ]
  • Adding a missing RequiredToolNotFound import. [ ]
  • As a UI/UX improvement, try and avoid printing an extended traceback if diffoscope runs out of memory. [ ]
  • Mark diffoscope as stable on PyPI.org. [ ]
  • Uploading version 252 to Debian unstable. [ ]

Website updates A huge number of notes were added to our website that were taken at our recent Reproducible Builds Summit held between October 31st and November 2nd in Hamburg, Germany. In particular, a big thanks to Arnout Engelen, Bernhard M. Wiedemann, Daan De Meyer, Evangelos Ribeiro Tzaras, Holger Levsen and Orhun Parmaks z. In addition to this, a number of other changes were made, including:

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:

Reproducibility testing framework The Reproducible Builds project operates a comprehensive testing framework (available at tests.reproducible-builds.org) in order to check packages and other artifacts for reproducibility. In October, a number of changes were made by Holger Levsen:
  • Debian-related changes:
    • Track packages marked as Priority: important in a new package set. [ ][ ]
    • Stop scheduling packages that fail to build from source in bookworm [ ] and bullseye. [ ].
    • Add old releases dashboard link in web navigation. [ ]
    • Permit re-run of the pool_buildinfos script to be re-run for a specific year. [ ]
    • Grant jbglaw access to the osuosl4 node [ ][ ] along with lynxis [ ].
    • Increase RAM on the amd64 Ionos builders from 48 GiB to 64 GiB; thanks IONOS! [ ]
    • Move buster to archived suites. [ ][ ]
    • Reduce the number of arm64 architecture workers from 24 to 16 in order to improve stability [ ], reduce the workers for amd64 from 32 to 28 and, for i386, reduce from 12 down to 8 [ ].
    • Show the entire build history of each Debian package. [ ]
    • Stop scheduling already tested package/version combinations in Debian bookworm. [ ]
  • Snapshot service for rebuilders
    • Add an HTTP-based API endpoint. [ ][ ]
    • Add a Gunicorn instance to serve the HTTP API. [ ]
    • Add an NGINX config [ ][ ][ ][ ]
  • System-health:
    • Detect failures due to HTTP 503 Service Unavailable errors. [ ]
    • Detect failures to update package sets. [ ]
    • Detect unmet dependencies. (This usually occurs with builds of Debian live-build.) [ ]
  • Misc-related changes:
    • do install systemd-ommd on jenkins. [ ]
    • fix harmless typo in squid.conf for codethink04. [ ]
    • fixup: reproducible Debian: add gunicorn service to serve /api for rebuilder-snapshot.d.o. [ ]
    • Increase codethink04 s Squid cache_dir size setting to 16 GiB. [ ]
    • Don t install systemd-oomd as it unfortunately kills sshd [ ]
    • Use debootstrap from backports when commisioning nodes. [ ]
    • Add the live_build_debian_stretch_gnome, debsums-tests_buster and debsums-tests_buster jobs to the zombie list. [ ][ ]
    • Run jekyll build with the --watch argument when building the Reproducible Builds website. [ ]
    • Misc node maintenance. [ ][ ][ ]
Other changes were made as well, however, including Mattia Rizzolo fixing rc.local s Bash syntax so it can actually run [ ], commenting away some file cleanup code that is (potentially) deleting too much [ ] and fixing the html_brekages page for Debian package builds [ ]. Finally, diagnosed and submitted a patch to add a AddEncoding gzip .gz line to the tests.reproducible-builds.org Apache configuration so that Gzip files aren t re-compressed as Gzip which some clients can t deal with (as well as being a waste of time). [ ]

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:

27 November 2023

Andrew Cater: 20231123 - UEFI install on a Raspberry Pi 4 - step by step instructions to a modified d-i

Motivation
Andy (RattusRattus) and I have been formalising instructions for using Pete Batard's version of Tianocore (and therefore UEFI booting) for the Raspberry Pi 4 together with a Debian arm64 netinst to make a modified Debian installer on a USB stick which "just works" for a Raspberry Pi 4.
Thanks also to Steve McIntyre for initial notes that got this working for us and also to Emmanuele Rocca for putting up some useful instructions for copying.

Recipe

Plug in a USB stick - use dmesg or your favourite method to see how it is identified.

Make a couple of mount points under /mnt - /mnt/data and /mnt/cdrom


1. Grab a USB stick, Partition using MBR. Make a single VFAT
partition, type 0xEF (i.e. EFI System Partition)

For a USB stick (identified as sdX) below:
$ sudo parted --script /dev/sdX mklabel msdos $ sudo parted --script /dev/sdX mkpart primary fat32 0% 100% $ sudo mkfs.vfat /dev/sdX1 $ sudo mount /dev/sdX1 /mnt/data/

Download an arm64 netinst.iso

https://cdimage.debian.org/debian-cd/current/arm64/iso-cd/debian-12.2.0-arm64-netinst.iso

2. Copy the complete contents of partition *1* from a Debian arm64
installer image into the filesystem (partition 1 is the installer
stuff itself) on the USB stick, in /

$ sudo kpartx -v -a debian-12.2.0-arm64-netinst.iso # Mount the first partition on the ISO and copy its contents to the stick $ sudo mount /dev/mapper/loop0p1 /mnt/cdrom/ $ sudo rsync -av /mnt/cdrom/ /mnt/data/ $ sudo umount /mnt/cdrom

3. Copy the complete contents of partition *2* from that Debian arm64
installer image into that filesystem (partition 2 is the ESP) on
the USB stick, in /

# Same story with the second partition on the ISO

$ sudo mount /dev/mapper/loop0p2 /mnt/cdrom/

$ sudo rsync -av /mnt/cdrom/ /mnt/data/ $ sudo umount /mnt/cdrom

$ sudo kpartx -d debian-testing-amd64-netinst.iso $ sudo umount /mnt/data


4. Grab the rpi edk2 build from https://github.com/pftf/RPi4/releases
(I used 1.35) and extract it. I copied the files there into *2*
places for now on the USB stick:

/ (so the Pi will boot using it)
/rpi4 (so we can find the files again later)

5. Add the preseed.cfg file (attached) into *both* of the two initrd
files on the USB stick

- /install.a64/initrd.gz and
- /install.a64/gtk/initrd.gz

cpio is an awful tool to use :-(. In each case:

$ cp /path/to/initrd.gz .
$ gunzip initrd.gz
$ echo preseed.cfg cpio -H newc -o -A -F initrd

$ gzip -9v initrd

$ cp initrd.gz /path/to/initrd.gz

If you look at the preseed file, it will do a few things:

- Use an early_command to unmount /media (to work around Debian bug
#1051964)

- Register a late_command call for /cdrom/finish-rpi (the next
file - see below) to run at the end of the installation.

- Force grub installation also to the EFI removable media path,
needed as the rpi doesn't store EFI boot variables.

- Stop the installer asking for firmware from removable media (as
the rpi4 will ask for broadcom bluetooth fw that we can't
ship. Can be ignored safely.)

6. Copy the finish-rpi script (attached) into / on the USB stick. It
will be run at the end of the installation, triggered via the
preseed. It does a couple of things:

- Copy the edk2 firmware files into the ESP on the system that's
just been installer

- Remove shim-signed from the installed systems, as there's a bug
that causes it to fail on rpi4. I need to dig into this to see
what the issue is.

That's it! Run the installer as normal, all should Just Work (TM).

BlueTooth didn't quite work : raspberrypi-firmware didn't install until adding a symlink for boot/efi to /boot/firmware

20231127 - This may not be necessary because raspberrypi-firmware path has been fixed

Preseed.cfg
# The preseed file itself causes a problem - the installer medium is
# left mounted on /medis so things break in cdrom-detect. Let's see if
# we can fix that!
d-i preseed/early_command string umount /media true

# Run our command to do rpi setup before reboot
d-i preseed/late_command string /cdrom/finish-rpi

# Force grub installation to the RM path
grub-efi-arm64 grub2/force_efi_extra_removable boolean true

# Don't prompt for missing firmware from removable media,
# e.g. broadcom bluetooth on the rpi.
d-i hw-detect/load_firmware boolean false

Finish.rpi
!/bin/sh

set -x

grep -q -a RPI4 /sys/firmware/acpi/tables/CSRT
if [ $? -ne 0 ]; then
echo "Not running on a Pi 4, exit!"
exit 0
fi

# Copy the rpi4 firmware binaries onto the installed system.
# Assumes the installer media is mounted on /cdrom.
cp -vr /cdrom/rpi4/. /target/boot/efi/.

# shim-signed doesn't seem happy on rpi4, so remove it
mount --bind /sys /target/sys
mount --bind /proc /target/proc
mount --bind /dev /target/dev

in-target apt-get remove --purge --autoremove -y shim-signed




26 November 2023

Andrew Cater: Back at ARM for MiniDebConf day 2 - Morning sessions 26th November 2023

Quick recap of slides and safety information for the day from Steve McIntyre
Now into the Release Team questions following a release team overview.A roomful of people all asking questions which are focused and provoke more questions - how unlike a Debian session :)May just have talked myself into giving a lightning talk this afternoon :)Now about to have a talk about from Sudip about OpenQA, kernel testing and automation

25 November 2023

Andrew Cater: ARM lecture theatre - MiniDebConf Cambridge day 1

And we're here - a couple of lectures in. Welcome from one Steve, deep internals of ARM from another Steve. A room filling with people - and now a lecture I really need to listen to on a machine I'd like to own. As ever, the hallway track is interesting - and you find people who know you from IRC or mailing lists. Four screens and a lecture theatre layout. Here we go.

Video team doing a great job, as ever - and our brand new talkmeister is doing a sterling job.

21 November 2023

Russ Allbery: Review: Thud!

Review: Thud!, by Terry Pratchett
Series: Discworld #34
Publisher: Harper
Copyright: October 2005
Printing: November 2014
ISBN: 0-06-233498-0
Format: Mass market
Pages: 434
Thud! is the 34th Discworld novel and the seventh Watch novel. It is partly a sequel to The Fifth Elephant, partly a sequel to Night Watch, and references many of the previous Watch novels. This is not a good place to start. Dwarfs and trolls have a long history of conflict, as one might expect between a race of creatures who specialize in mining and a race of creatures whose vital organs are sometimes the targets of that mining. The first battle of Koom Valley was the place where that enmity was made concrete and given a symbol. Now that there are large dwarf and troll populations in Ankh-Morpork, the upcoming anniversary of that battle is the excuse for rising tensions. Worse, Grag Hamcrusher, a revered deep-down dwarf and a dwarf supremacist, is giving incendiary speeches about killing all trolls and appears to be tunneling under the city. Then whispers run through the city's dwarfs that Hamcrusher has been murdered by a troll. Vimes has no patience for racial tensions, or for the inspection of the Watch by one of Vetinari's excessively competent clerks, or the political pressure to add a vampire to the Watch over his prejudiced objections. He was already grumpy before the murder and is in absolutely no mood to be told by deep-down dwarfs who barely believe that humans exist that the murder of a dwarf underground is no affair of his. Meanwhile, The Battle of Koom Valley by Methodia Rascal has been stolen from the Ankh-Morpork Royal Art Museum, an impressive feat given that the painting is ten feet high and fifty feet long. It was painted in impressive detail by a madman who thought he was a chicken, and has been the spark for endless theories about clues to some great treasure or hidden knowledge, culminating in the conspiratorial book Koom Valley Codex. But the museum prides itself on allowing people to inspect and photograph the painting to their heart's content and was working on a new room to display it. It's not clear why someone would want to steal it, but Colon and Nobby are on the case. This was a good time to read this novel. Sadly, the same could be said of pretty much every year since it was written. "Thud" in the title is a reference to Hamcrusher's murder, which was supposedly done by a troll club that was found nearby, but it's also a reference to a board game that we first saw in passing in Going Postal. We find out a lot more about Thud in this book. It's an asymmetric two-player board game that simulates a stylized battle between dwarf and troll forces, with one player playing the trolls and the other playing the dwarfs. The obvious comparison is to chess, but a better comparison would be to the old Steve Jackson Games board game Ogre, which also featured asymmetric combat mechanics. (I'm sure there are many others.) This board game will become quite central to the plot of Thud! in ways that I thought were ingenious. I thought this was one of Pratchett's best-plotted books to date. There are a lot of things happening, involving essentially every member of the Watch that we've met in previous books, and they all matter and I was never confused by how they fit together. This book is full of little callbacks and apparently small things that become important later in a way that I found delightful to read, down to the children's book that Vimes reads to his son and that turns into the best scene of the book. At this point in my Discworld read-through, I can see why the Watch books are considered the best sub-series. It feels like Pratchett kicks the quality of writing up a notch when he has Vimes as a protagonist. In several books now, Pratchett has created a villain by taking some human characteristic and turning it into an external force that acts on humans. (See, for instance the Gonne in Men at Arms, or the hiver in A Hat Full of Sky.) I normally do not like this plot technique, both because I think it lets humans off the hook in a way that cheapens the story and because this type of belief has a long and bad reputation in religions where it is used to dodge personal responsibility and dehumanize one's enemies. When another of those villains turned up in this book, I was dubious. But I think Pratchett pulls off this type of villain as well here as I've seen it done. He lifts up a facet of humanity to let the reader get a better view, but somehow makes it explicit that this is concretized metaphor. This force is something people create and feed and choose and therefore are responsible for. The one sour note that I do have to complain about is that Pratchett resorts to some cheap and annoying "men are from Mars, women are from Venus" nonsense, mostly around Nobby's subplot but in a few other places (Sybil, some of Angua's internal monologue) as well. It's relatively minor, and I might let it pass without grumbling in other books, but usually Pratchett is better on gender than this. I expected better and it got under my skin. Otherwise, though, this was a quietly excellent book. It doesn't have the emotional gut punch of Night Watch, but the plotting is superb and the pacing is a significant improvement over The Fifth Elephant. The parody is of The Da Vinci Code, which is both more interesting than Pratchett's typical movie parodies and delightfully subtle. We get more of Sybil being a bad-ass, which I am always here for. There's even some lovely world-building in the form of dwarven Devices. I love how Pratchett has built Vimes up into one of the most deceptively heroic figures on Discworld, but also shows all of the support infrastructure that ensures Vimes maintain his principles. On the surface, Thud! has a lot in common with Vimes's insistently moral stance in Jingo, but here it is more obvious how Vimes's morality happens in part because his wife, his friends, and his boss create the conditions for it to thrive. Highly recommended to anyone who has gotten this far. Rating: 9 out of 10

16 November 2023

Dimitri John Ledkov: Ubuntu 23.10 significantly reduces the installed kernel footprint


Photo by Pixabay
Ubuntu systems typically have up to 3 kernels installed, before they are auto-removed by apt on classic installs. Historically the installation was optimized for metered download size only. However, kernel size growth and usage no longer warrant such optimizations. During the 23.10 Mantic Minatour cycle, I led a coordinated effort across multiple teams to implement lots of optimizations that together achieved unprecedented install footprint improvements.

Given a typical install of 3 generic kernel ABIs in the default configuration on a regular-sized VM (2 CPU cores 8GB of RAM) the following metrics are achieved in Ubuntu 23.10 versus Ubuntu 22.04 LTS:

  • 2x less disk space used (1,417MB vs 2,940MB, including initrd)

  • 3x less peak RAM usage for the initrd boot (68MB vs 204MB)

  • 0.5x increase in download size (949MB vs 600MB)

  • 2.5x faster initrd generation (4.5s vs 11.3s)

  • approximately the same total time (103s vs 98s, hardware dependent)


For minimal cloud images that do not install either linux-firmware or modules extra the numbers are:

  • 1.3x less disk space used (548MB vs 742MB)

  • 2.2x less peak RAM usage for initrd boot (27MB vs 62MB)

  • 0.4x increase in download size (207MB vs 146MB)


Hopefully, the compromise of download size, relative to the disk space & initrd savings is a win for the majority of platforms and use cases. For users on extremely expensive and metered connections, the likely best saving is to receive air-gapped updates or skip updates.

This was achieved by precompressing kernel modules & firmware files with the maximum level of Zstd compression at package build time; making actual .deb files uncompressed; assembling the initrd using split cpio archives - uncompressed for the pre-compressed files, whilst compressing only the userspace portions of the initrd; enabling in-kernel module decompression support with matching kmod; fixing bugs in all of the above, and landing all of these things in time for the feature freeze. Whilst leveraging the experience and some of the design choices implementations we have already been shipping on Ubuntu Core. Some of these changes are backported to Jammy, but only enough to support smooth upgrades to Mantic and later. Complete gains are only possible to experience on Mantic and later.

The discovered bugs in kernel module loading code likely affect systems that use LoadPin LSM with kernel space module uncompression as used on ChromeOS systems. Hopefully, Kees Cook or other ChromeOS developers pick up the kernel fixes from the stable trees. Or you know, just use Ubuntu kernels as they do get fixes and features like these first.

The team that designed and delivered these changes is large: Benjamin Drung, Andrea Righi, Juerg Haefliger, Julian Andres Klode, Steve Langasek, Michael Hudson-Doyle, Robert Kratky, Adrien Nader, Tim Gardner, Roxana Nicolescu - and myself Dimitri John Ledkov ensuring the most optimal solution is implemented, everything lands on time, and even implementing portions of the final solution.

Hi, It's me, I am a Staff Engineer at Canonical and we are hiring https://canonical.com/careers.

Lots of additional technical details and benchmarks on a huge range of diverse hardware and architectures, and bikeshedding all the things below:

For questions and comments please post to Kernel section on Ubuntu Discourse.



6 October 2023

Emanuele Rocca: Custom Debian Installer and Kernel on a USB stick

There are many valid reasons to create a custom Debian Installer image. You may need to pass some special arguments to the kernel, use a different GRUB version, automate the installation by means of preseeding, use a custom kernel, or modify the installer itself.
If you have a EFI system, which is probably the case in 2023, there is no need to learn complex procedures in order to create a custom Debian Installer stick.
The source of many frustrations is that the ISO format for CDs/DVDs is read-only, but you can just create a VFAT filesystem on a USB stick, copy all ISO contents onto the stick itself, and modify things at will.

Create a writable USB stick
First create a FAT32 filesystem on the removable device and mount it. The device is sdX in the example.
$ sudo parted --script /dev/sdX mklabel msdos
$ sudo parted --script /dev/sdX mkpart primary fat32 0% 100%
$ sudo mkfs.vfat /dev/sdX1
$ sudo mount /dev/sdX1 /mnt/data/
Then copy to the USB stick the installer ISO you would like to modify, debian-testing-amd64-netinst.iso here.
$ sudo kpartx -v -a debian-testing-amd64-netinst.iso
# Mount the first partition on the ISO and copy its contents to the stick
$ sudo mount /dev/mapper/loop0p1 /mnt/cdrom/
$ sudo rsync -av /mnt/cdrom/ /mnt/data/
$ sudo umount /mnt/cdrom
# Same story with the second partition on the ISO
$ sudo mount /dev/mapper/loop0p2 /mnt/cdrom/
$ sudo rsync -av /mnt/cdrom/ /mnt/data/
$ sudo umount /mnt/cdrom
$ sudo kpartx -d debian-testing-amd64-netinst.iso
$ sudo umount /mnt/data
Now try booting from the USB stick just to verify that everything went well and we can start customizing the image.

Boot loader, preseeding, installer hacks
The easiest things we can change now are the shim, GRUB, and GRUB s configuration. The USB stick contains the shim under /EFI/boot/bootx64.efi, while GRUB is at /EFI/boot/grubx64.efi. This means that if you want to test a different shim / GRUB version, you just replace the relevant files. That s it. Take for example /usr/lib/grub/x86_64-efi/monolithic/grubx64.efi from the package grub-efi-amd64-bin, or the signed version from grub-efi-amd64-signed and copy them under /EFI/boot/grubx64.efi. Or perhaps you want to try out systemd-boot? Then take /usr/lib/systemd/boot/efi/systemd-bootx64.efi from the package systemd-boot-efi, copy it to /EFI/boot/bootx64.efi and you re good to go. Figuring out the right systemd-boot configuration needed to start the Installer is left as an exercise.
By editing /boot/grub/grub.cfg you can pass arbitrary arguments to the kernel and the Installer itself. See the official Installation Guide for a comprehensive list of boot parameters.
One very commong thing to do is automating the installation using a preseed file. Add the following to the kernel command line: preseed/file=/cdrom/preseed.cfg and create a /preseed.cfg file on the USB stick. As a little example:
d-i time/zone select Europe/Rome
d-i passwd/root-password this-is-the-root-password
d-i passwd/root-password-again this-is-the-root-password
d-i passwd/user-fullname string Emanuele Rocca
d-i passwd/username string ema
d-i passwd/user-password password lol-haha-uh
d-i passwd/user-password-again password lol-haha-uh
d-i apt-setup/no_mirror boolean true
d-i popularity-contest/participate boolean true
tasksel tasksel/first multiselect standard
See Steve McIntyre s awesome page with the full list of available settings and their description: https://preseed.einval.com/debian-preseed/.
Two noteworthy settings are early_command and late_command. They can be used to execute arbitrary commands and provide thus extreme flexibility! You can go as far as replacing parts of the installer with a sed command, or maybe wgetting an entirely different file. This is a fairly easy way to test minor Installer patches. As an example, I ve once used this to test a patch to grub-installer:
d-i partman/early_command string wget https://people.debian.org/~ema/grub-installer-1035085-1 -O /usr/bin/grub-installer
Finally, the initrd contains all early stages of the installer. It s easy to unpack it, modify whatever component you like, and repack it. Say you want to change a given udev rule:
$ mkdir /tmp/new-initrd
$ cd /tmp/new-initrd
$ zstdcat /mnt/data/install.a64/initrd.gz   sudo cpio -id
$ vi lib/udev/rules.d/60-block.rules
$ find .   cpio -o -H newc   zstd --stdout > /mnt/data/install.a64/initrd.gz

Custom udebs
From a basic architectural standpoint the Debian Installer can be seen as an initrd that loads a series of special Debian packages called udebs. In the previous section we have seen how to (ab)use early_command to replace one of the scripts used by the Installer, namely grub-installer. It turns out that such script is installed by a udeb, so let s do things right and build a new Installer ISO with our custom grub udeb.
Fetch the code for the grub-installer udeb, make your changes and build it with a classic dpkg-buildpackage -rfakeroot.
Then get the Installer code and install all dependencies:
$ git clone https://salsa.debian.org/installer-team/debian-installer/
$ cd debian-installer/
$ sudo apt build-dep .
Now add the grub-installer udeb to the localudebs directory and create a new netboot image:
$ cp /path/to/grub-installer_1.198_arm64.udeb build/localudebs/
$ cd build
$ fakeroot make clean_netboot build_netboot
Give it some time, soon enough you ll have a brand new ISO to test under dest/netboot/mini.iso.

Custom kernel
Perhaps there s a kernel configuration option you need to enable, or maybe you need a more recent kernel version than what is available in sid.
The Debian Linux Kernel Handbook has all the details for how to do things properly, but here s a quick example.
Get the Debian kernel packaging from salsa and generate the upstream tarball:
$ git clone https://salsa.debian.org/kernel-team/linux/
$ ./debian/bin/genorig.py https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux-stable.git
For RC kernels use the repo from Linus instead of linux-stable.
Now do your thing, for instance change a config setting by editing debian/config/amd64/config. Don t worry about where you put it in the file, there s a tool from https://salsa.debian.org/kernel-team/kernel-team to fix that:
$ /path/to/kernel-team/utils/kconfigeditor2/process.py .
Now build your kernel:
$ export MAKEFLAGS=-j$(nproc)
$ export DEB_BUILD_PROFILES='pkg.linux.nokerneldbg pkg.linux.nokerneldbginfo pkg.linux.notools nodoc'
$ debian/rules orig
$ debian/rules debian/control
$ dpkg-buildpackage -b -nc -uc
After some time, if everything went well, you should get a bunch of .deb files as well as a .changes file, linux_6.6~rc3-1~exp1_arm64.changes here. To generate the udebs used by the Installer you need to first get a linux-signed .dsc file, and then build it with sbuild in this example:
$ /path/to/kernel-team/scripts/debian-test-sign linux_6.6~rc3-1~exp1_arm64.changes
$ sbuild --dist=unstable --extra-package=$PWD linux-signed-arm64_6.6~rc3+1~exp1.dsc
Excellent, now you should have a ton of .udebs. To build a custom installer image with this kernel, copy them all under debian-installer/build/localudebs/ and then run fakeroot make clean_netboot build_netboot as described in the previous section. In case you are trying to use a different kernel version from what is currently in sid, you will have to install the linux-image package on the system building the ISO, and change LINUX_KERNEL_ABI in build/config/common. The linux-image dependency in debian/control probably needs to be tweaked as well.
That s it, the new Installer ISO should boot with your custom kernel!
There is going to be another minor obstacle though, as anna will complain that your new kernel cannot be found in the archive. Copy the kernel udebs you have built onto a vfat formatted USB stick, switch to a terminal, and install them all with udpkg:
~ # udpkg -i *.udeb
Now the installation should proceed smoothly.

28 August 2023

Jonathan McDowell: OMGWTFBBQ 2023

A person wearing an OMGWTFBBQ Catering t-shirt standing in front of a BBQ. Various uncooked burgers are visible. As is traditional for the UK August Bank Holiday weekend I made my way to Cambridge for the Debian UK BBQ. As was pointed out we ve been doing this for more than 20 years now, and it s always good to catch up with old friends and meet new folk. Thanks to Collabora, Codethink, and Andy for sponsoring a bunch of tasty refreshments. And, of course, thanks to Steve for hosting us all.

27 August 2023

Steve McIntyre: We're back!

It's August Bank Holiday Weekend, we're in Cambridge. It must be the Debian UK OMGWTFBBQ!. We're about halfway through, and we've already polished off lots and lots of good food and beer. Lars is making pancakes as I write this, :-) We had an awesome game of Mao last night. People are having fun! Many thanks to a number of awesome friendly people for again sponsoring the important refreshments for the weekend. It's hungry/thirsty work celebrating like this!

26 August 2023

Andrew Cater: 20230826 OMGWTFBBQ - Cambridge is waking up

The meat has been fetched: those of us in the house are about to get bacon sandwiches. Pepper the dog is in the garden. Time for the mayhem to start, I think.
Various folk are travelling here so it will soon be crowded: the weather is sunny but cool and it looks good for a three day weekend.

This is a huge effort that falls to Steve and Jo and a huge disruption for them each year - for which many thanks, as ever. [And, as is traditional on this blog, the posts only ever seem to appear from Cambridge].

2 August 2023

Debian Brasil: Participa o do Debian na Campus Party Brasil 2023

Mais uma edi o da Campus Party Brasil aconteceu na cidade de S o Paulo entre os dias 25 e 30 de Julho de 2023. Novamente a comunidade Debian Brasil se fez presente. Durante os dias no espa o disponibilizado, realizamos algumas atividades:
- Distribui o de brindes (adesivos, copos, cord o de crach );
- Mini oficina sobre como contribuir para a equipe de tradu o;
- Mini oficina sobre empacotamento;
- Assinatura de chaves;
- Informa es sobre o projeto; Durante todos os dias, havia sempre uma pessoa dispon vel para passar informa es sobre o que o Debian e as diversas formas de contribuir. Durante todo o evento, estimamos que ao menos 700 pessoas interagiram de alguma forma com nossa comunidade. Diversas pessoas, aproveitaram a oportunidade para aproveitar pelo excelente trabalho realizado pelo projeto no Debian 12 - Bookworm. Segue algumas fotos tiradas durante o evento! CPBR15
Espa o da Comunidade no Evento.
CPBR15
Romulo, visitante do espa o com Daniel Lenharo.
CPBR15
Alguns brindes que estavam a disposi o do p blico.
CPBR15
Vis o do espa o.
CPBR15
Adesivo com a Arte de 30 anos feita pelo Jefferson.
CPBR15
Pessoal no espa o da comunidade.
CPBR15
Mini curso de empacotamento, realizado pelo Charles.
CPBR15
Pessoal que esteve envolvido nas atividades da comunidade.

1 August 2023

Debian Brasil: Participa o do Debian na Campus Party Brasil 2023

Mais uma edi o da Campus Party Brasil aconteceu na cidade de S o Paulo entre os dias 25 e 30 de Julho de 2023. Novamente a comunidade Brasileira se fez presente. Durante os dias no espa o disponibilizado, realizamos algumas atividades:
- Distribui o de brindes (Adesivos, Copos, Cord o de crach );
- Mini oficina sobre como contribuir para a equipe de tradu o;
- Mini oficina sobre empacotamento;
- Informa es sobre o projeto; Durante todos os dias, havia sempre uma pessoa dispon vel para passar informa es sobre o que o Debian, formas de contribuir. Durante todo o evento, estimamos que ao menos 700 pessoas interagiram de alguma forma com nossa comunidade. Diversas pessoas, aproveitaram a oportunidade para aproveitar pelo excelente trabalho realizado pelo projeto no Debian 12 - Bookworm. Segue algumas fotos tiradas durante o evento! CPBR15
Espa o da Comunidade no Evento.
CPBR15
Romulo, visitante do espa o com Daniel Lenharo.
CPBR15
Alguns brindes que estavam a disposi o do p blico.
CPBR15
Vis o do espa o.
CPBR15
Adesivo com a Arte de 30 anos feita pelo Jefferson.
CPBR15
Pessoal no espa o da comunidade.
CPBR15
Mini curso de empacotamento, realizado pelo Charles.
CPBR15
Pessoal que esteve envolvido nas atividades da comunidade.

22 July 2023

Andrew Cater: 20230722 - Releasing Debian testing for Debian Bookworm point release 12.1

And so we're back at Steve's in Cambridge for release testing. A few testers here: we're now well into testing the various iso images.So we have Sledge, RattusRattus, Isy, smcv and myself. We've also been joined here by Helen who has just done her first install. Online we've got a couple of new folk - luna, The_Blode. Thanks to everyone involved - we always need all the help we can get.
Cold and grey outside: usual warmth in here. Also the usual snake of cables to trip over across the floor.

1 July 2023

Debian Brasil: MiniDebConf Bras lia 2023 - um breve relato

Minidebconf2033 palco No per odo de 25 a 27 de maio, Bras lia foi palco da MiniDebConf 2023. Esse encontro, composto por diversas atividades como palestras, oficinas, sprints, BSP (Bug Squashing Party), assinatura de chaves, eventos sociais e hacking, teve como principal objetivo reunir a comunidade e celebrar o maior projeto de Software Livre do mundo: o Debian. A MiniDebConf Bras lia 2023 foi um sucesso gra as participa o de todas e todos, independentemente do n vel de conhecimento sobre o Debian. Valorizamos a presen a tanto dos(as) usu rios(as) iniciantes que est o se familiarizando com o sistema quanto dos(as) desenvolvedores(as) oficiais do projeto. O esp rito de acolhimento e colabora o esteve presente em todos os momentos. As MiniDebConfs s o encontros locais organizados por membros do Projeto Debian, visando objetivos semelhantes aos da DebConf, por m em mbito regional. Ao longo do ano, eventos como esse ocorrem em diferentes partes do mundo, fortalecendo a comunidade Debian. Minidebconf2023 placa Atividades A programa o da MiniDebConf foi intensa e diversificada. Nos dias 25 e 26 (quinta e sexta-feira), tivemos palestras, debates, oficinas e muitas atividades pr ticas. J no dia 27 (s bado), ocorreu o Hacking Day, um momento especial em que os(as) colaboradores(as) do Debian se reuniram para trabalhar em conjunto em v rios aspectos do projeto. Essa foi a vers o brasileira da Debcamp, tradi o pr via DebConf. Nesse dia, priorizamos as atividades pr ticas de contribui o ao projeto, como empacotamento de softwares, tradu es, assinaturas de chaves, install fest e a Bug Squashing Party. Minidebconf2023 auditorio

Minidebconf2023 oficina N meros da edi o Os n meros do evento impressionam e demonstram o envolvimento da comunidade com o Debian. Tivemos 236 inscritos(as), 20 palestras submetidas, 14 volunt rios(as) e 125 check-ins realizados. Al m disso, nas atividades pr ticas, tivemos resultados significativos, como 7 novas instala es do Debian GNU/Linux, a atualiza o de 18 pacotes no reposit rio oficial do projeto Debian pelos participantes e a inclus o de 7 novos contribuidores na equipe de tradu o. Destacamos tamb m a participa o da comunidade de forma remota, por meio de transmiss es ao vivo. Os dados anal ticos revelam que nosso site obteve 7.058 visualiza es no total, com 2.079 visualiza es na p gina principal (que contava com o apoio de nossos patrocinadores), 3.042 visualiza es na p gina de programa o e 104 visualiza es na p gina de patrocinadores. Registramos 922 usu rios(as) nicos durante o evento. No YouTube, a transmiss o ao vivo alcan ou 311 visualiza es, com 56 curtidas e um pico de 20 visualiza es simult neas. Foram incr veis 85,1 horas de exibi o, e nosso canal conquistou 30 novos inscritos(as). Todo esse engajamento e interesse da comunidade fortalecem ainda mais a MiniDebConf. Minidebconf2023 palestrantes Fotos e v deos Para revivermos os melhores momentos do evento, temos dispon veis fotos e v deos. As fotos podem ser acessadas em: https://deb.li/pbsb2023. J os v deos com as grava es das palestras est o dispon veis no seguinte link: https://deb.li/vbsb2023. Para manter-se atualizado e conectar-se com a comunidade Debian Bras lia, siga-nos em nossas redes sociais: Agradecimentos Gostar amos de agradecer profundamente a todos(as) os(as) participantes, organizadores(as), patrocinadores e apoiadores(as) que contribu ram para o sucesso da MiniDebConf Bras lia 2023. Em especial, expressamos nossa gratid o aos patrocinadores Ouro: Pencillabs, Globo, Policorp e Toradex Brasil, e ao patrocinador Prata, 4-Linux. Tamb m agradecemos Finatec e ao Instituto para Conserva o de Tecnologias Livres (ICTL) pelo apoio. Minidebconf2023 coffee A MiniDebConf Bras lia 2023 foi um marco para a comunidade Debian, demonstrando o poder da colabora o e do Software Livre. Esperamos que todas e todos tenham desfrutado desse encontro enriquecedor e que continuem participando ativamente das pr ximas iniciativas do Projeto Debian. Juntos, podemos fazer a diferen a! Minidebconf2023 fotos oficial

24 June 2023

Steve Kemp: Simple REPL for CP/M, in Z80 assembly

So my previous post documented a couple of simple "scripting languages" for small computers, allowing basic operations in a compact/terse fashion. I mentioned that I might be tempted to write something similar for CP/M, in Z80 assembly, and the result is here: To sum up it allows running programs like this:
0m 16k rP _ _ 
C3 03 EA 00 00 C3 06 DC 00 00 00 00 00 00 00 00
Numbers automatically get saved to the A-register, the accumulator. In addition to that there are three dedicated registers: So the program above: TLDR: Dump the first sixteen bytes of RAM, at address 0x0000, to the console. Though this program allows delays, RAM read/write, I/O port input and output, as well as loops it's both kinda fun, and kinda pointless. I guess you could spend hours flashing lights and having other similar fun. But only if you're like me! All told the code compiles down to about 800 bytes and uses less than ten bytes of RAM to store register-state. It could be smaller with some effort, but it was written a bit adhoc and I think I'm probably done now.

22 June 2023

Steve Kemp: Simple toy languages

Recently I was looking around the internet and looking for something to do with some ESP8266 devices, which I've been neglecting over recent years.
When I was on paternity-leave, five years ago, I decided I wanted a new hobby for my "down" time. I had two obvious choices a) developing applications for mobiles, or b) working with "hardware". I chose the latter.
By accident I came across a couple of simple scripting languages, FORTH-esque. Sample usage looks something like this (which obviously sends the command over a serial-device to the connected-board):
$ echo '5  6d 1o 100m 0o 100m  ' >/dev/cu.usbmodem12341
That's a little terse, but briefly: The end result is a blinking LED, for five iterations anyway. The code for this interpreter is described in the following link, with the code in the linked gist: This is derived from an older, and simpler, project which has a similar focus but slightly different built-in operations (and which lacks loops/conditionals): Both of these implementations are very similar, I guess due to the shared history and obvious FORTH-inspiration. Each allows port I/O, delays, and simple math opertions. We can pretend they're stack-based, though there are some differences and some niggles. I'm kinda tempted to port one of them to Z80 assembly, and see if I can get it running under CP/M. I guess I could add a REPL for interactive use, though without actual hardware connected to my single-board computer it might all feel a little pointless. Then again I have Turbo Pascal, and even a tiny C-compiler, so I guess with those in mind any toy-language is pointless in a completely different regard.

29 May 2023

Russ Allbery: Book haul

I think this is partial because I also have a stack of other books that I missed recording. At some point, I should stop using this method to track book acquisitions in favor of one of the many programs intended for this purpose, but it's in the long list of other things I really should do one of these days. As usual, I have already read and reviewed a few of these. I might be getting marginally better at reading books shortly after I acquire them? Maybe? Steven Brust Tsalmoth (sff)
C.L. Clark The Faithless (sff)
Oliver Darkshire Once Upon a Tome (non-fiction)
Hernan Diaz Trust (mainstream)
S.B. Divya Meru (sff)
Kate Elliott Furious Heaven (sff)
Steven Flavall Before We Go Live (non-fiction)
R.F. Kuang Babel (sff)
Laurie Marks Dancing Jack (sff)
Arkady Martine Rose/House (sff)
Madeline Miller Circe (sff)
Jenny Odell Saving Time (non-fiction)
Malka Older The Mimicking of Known Successes (sff)
Sabaa Tahir An Ember in the Ashes (sff)
Emily Tesh Some Desperate Glory (sff)
Valerie Valdes Chilling Effect (sff)

Next.