Beyond Debian: Useful for other distros too Every two years Debian releases a new major version of its Stable series, meaning the differences between consecutive Debian Stable releases represent two years of new developments both in Debian as an organization and its native packages, but also in all other packages which are also shipped by other distributions (which are getting into this new Stable release). If you're not paying close attention to everything that's going on all the time in the Linux world, you miss a lot of the nice new features and tools. It's common for people to only realize there's a cool new trick available only years after it was first introduced. Given these considerations, the tips that I'm describing will eventually be available in whatever other distribution you use, be it because it's a Debian derivative or because it just got the same feature from the upstream project. I'm not going to list "passive" features (as good as they can be), the focus here is on new features that might change how you configure and use your machine, with a mix between productivity and performance.

Debian 13 - Trixie I have been a Debian Testing user for longer than 10 years now (and I recommend it for non-server users), so I'm not usually keeping track of all the cool features arriving in the new Stable releases because I'm continuously receiving them through the Debian Testing rolling release. Nonetheless, as a Debian Developer I'm in a good position to point out the ones I can remember. I would also like other Debian Developers to do the same as I'm sure I would learn something new. The Debian 13 release notes contain a "What's new" section , which lists the first two items here and a few other things, in other words, take my list as an addition to the release notes. Debian 13 was released on 2025-08-09, and these are nice things you shouldn't miss in the new release, with a bonus one not tied to the Debian 13 release.

1) wcurl Have you ever had to download a file from your terminal using curl and didn't remember the parameters needed? I did. Nowadays you can use wcurl; "a command line tool which lets you download URLs without having to remember any parameters." Simply call wcurl with one or more URLs as parameters and it will download all of them in parallel, performing retries, choosing the correct output file name, following redirects, and more. Try it out:

wcurl example.com

wcurl comes installed as part of the curl package on Debian 13 and in any other distribution you can imagine, starting with curl 8.14.0. I've written more about wcurl in its release announcement and I've done a lightning talk presentation in DebConf24, which is linked in the release announcement.

2) HTTP/3 support in curl Debian has become the first stable Linux distribution to ship curl with support for HTTP/3. I've written about this in July 2024, when we first enabled it. Note that we first switched the curl CLI to GnuTLS, but then ended up releasing the curl CLI linked with OpenSSL (as support arrived later). Debian was the first stable Linux distro to enable it, and within rolling-release-based distros; Gentoo enabled it first in their non-default flavor of the package and Arch Linux did it three months before we pushed it to Debian Unstable/Testing/Stable-backports, kudos to them! HTTP/3 is not used by default by the curl CLI, you have to enable it with --http3 or --http3-only. Try it out:

curl --http3 https://www.example.org
curl --http3-only https://www.example.org

3) systemd soft-reboot Starting with systemd v254, there's a new soft-reboot option, it's an userspace-only reboot, much faster than a full reboot if you don't need to reboot the kernel. You can read the announcement from the systemd v254 GitHub release Try it out:

# This will reboot your machine!
systemctl soft-reboot

4) apt --update Are you tired of being required to run sudo apt update just before sudo apt upgrade or sudo apt install $PACKAGE? So am I! The new --update option lets you do both things in a single command:

sudo apt --update upgrade
sudo apt --update install $PACKAGE

I love this, but it's still not yet where it should be, fingers crossed for a simple apt upgrade to behave like other package managers by updating its cache as part of the task, maybe in Debian 14? Try it out:

sudo apt upgrade --update
# The order doesn't matter
sudo apt --update upgrade

This is especially handy for container usage, where you have to update the apt cache before installing anything, for example:

podman run debian:stable bin/bash -c 'apt install --update -y curl'

5) powerline-go powerline-go is a powerline-style prompt written in Golang, so it's much more performant than its Python alternative powerline. powerline-style prompts are quite useful to show things like the current status of the git repo in your working directory, exit code of the previous command, presence of jobs in the background, whether or not you're in an ssh session, and more. Try it out:

sudo apt install powerline-go

Then add this to your .bashrc:

function _update_ps1()  
    PS1="$(/usr/bin/powerline-go -error $? -jobs $(jobs -p   wc -l))"

    # Uncomment the following line to automatically clear errors after showing
    # them once. This not only clears the error for powerline-go, but also for
    # everything else you run in that shell. Don't enable this if you're not
    # sure this is what you want.

    #set "?"
 

if [ "$TERM" != "linux" ] && [ -f "/usr/bin/powerline-go" ]; then
    PROMPT_COMMAND="_update_ps1; $PROMPT_COMMAND"
fi

Or this to .zshrc:

function powerline_precmd()  
    PS1="$(/usr/bin/powerline-go -error $? -jobs $ $ (%):%j :-0 )"

    # Uncomment the following line to automatically clear errors after showing
    # them once. This not only clears the error for powerline-go, but also for
    # everything else you run in that shell. Don't enable this if you're not
    # sure this is what you want.

    #set "?"
 

If you'd like to have your prompt start in a newline, like I have in the screenshot above, you just need to set -newline in the powerline-go invocation in your .bashrc/.zshrc.

6) Gnome System Monitor Extension Tips number 6 and 7 are for Gnome users. Gnome is now shipping a system monitor extension which lets you get a glance of the current load of your machine from the top bar. I've found this quite useful for machines where I'm required to install third-party monitoring software that tends to randomly consume more resources than it should. If I feel like my machine is struggling, I can quickly glance at its load to verify if it's getting overloaded by some process. The extension is not as complete as system-monitor-next, not showing temperatures or histograms, but at least it's officially part of Gnome, easy to install and supported by them. Try it out:

sudo apt install gnome-system-monitor gnome-shell-extension-manager

And then enable the extension from the "Extension Manager" application.

7) Gnome setting for battery charging profile After having to learn more about batteries in order to get into FPV drones, I've come to have a bigger appreciation for solutions that minimize the inevitable loss of capacity that accrues over time. There's now a "Battery Charging" setting (under the "Power") section which lets you choose between two different profiles: "Maximize Charge" and "Preserve Battery Health". On supported laptops, this setting is an easy way to set thresholds for when charging should start and stop, just like you could do it with the tlp package, but now from the Gnome settings. To increase the longevity of my laptop battery, I always keep it at "Preserve Battery Health" unless I'm traveling. What I would like to see next is support for choosing different "Power Modes" based on whether the laptop is plugged-in, and based on the battery charge percentage. There's a GNOME issue tracking this feature, but there's some pushback on whether this is the right thing to expose to users. In the meantime, there are some workarounds mentioned in that issue which people who really want this feature can follow. If you would like to learn more about batteries; Battery University is a great starting point, besides getting into FPV drones and being forced to handle batteries without a Battery Management System (BMS). And if by any chance this sparks your interest in FPV drones, Joshua Bardwell's YouTube channel is a great resource: @JoshuaBardwell.

8) Lazygit Emacs users are already familiar with the legendary magit; a terminal-based UI for git. Lazygit is an alternative for non-emacs users, you can integrate it with neovim or just use it directly. I'm still playing with lazygit and haven't integrated it into my workflows, but so far it has been a pleasant experience. You should check out the demos from the lazygit GitHub page. Try it out:

sudo apt install lazygit

And then call lazygit from within a git repository.

9) neovim neovim has been shipped in Debian since 2016, but upstream has been doing a lot of work to improve the experience out-of-the-box in the last couple of years. If you're a neovim poweruser, you're likely not installing it from the official repositories, but for those that are, Debian 13 comes with version 0.10.4, which brings the following improvements compared to the version in Debian 12:

• Treesitter support for C, Lua, Markdown, with the possibility of adding any other languages as needed;
• Better spellchecking due to treesitter integration (spellsitter);
• Mouse support enabled by default;
• Commenting support out-of-the-box; Check :h commenting for details, but the tl;dr is that you can use gcc to comment the current line and gc to comment the current selection.
• OSC52 support. Especially handy for those using neovim over an ssh connection, this protocol lets you copy something from within the neovim process into the clipboard of the machine you're using to connect through ssh. In other words, you can copy from neovim running in a host over ssh and paste it in the "outside" machine.

10) [Bonus] Running old Debian releases The bonus tip is not specific to the Debian 13 release, but something I've recently learned in the #debian-devel IRC channel. Did you know there are usable container images for all past Debian releases? I'm not talking "past" as in "some of the older releases", I'm talking past as in "literally every Debian release, including the very first one". Tianon Gravi "tianon" is the Debian Developer responsible for making this happen, kudos to him! There's a small gotcha that the releases Buzz (1.1) and Rex (1.2) require a 32-bit host, otherwise you will get the error Out of virtual memory!, but starting with Bo (1.3) all should work in amd64/arm64. Try it out:

sudo apt install podman

podman run -it docker.io/debian/eol:bo

Don't be surprised when noticing that apt/apt-get is not available inside the container, that's because apt first appeared in Debian Slink (2.1).

Changes since publication

2025-08-30

• Mention that Arch also enabled HTTP/3.

Beyond Debian: Useful for other distros too Every two years Debian releases a new major version of its Stable series, meaning the differences between consecutive Debian Stable releases represent two years of new developments both in Debian as an organization and its native packages, but also in all other packages which are also shipped by other distributions (which are getting into this new Stable release). If you're not paying close attention to everything that's going on all the time in the Linux world, you miss a lot of the nice new features and tools. It's common for people to only realize there's a cool new trick available only years after it was first introduced. Given these considerations, the tips that I'm describing will eventually be available in whatever other distribution you use, be it because it's a Debian derivative or because it just got the same feature from the upstream project. I'm not going to list "passive" features (as good as they can be), the focus here is on new features that might change how you configure and use your machine, with a mix between productivity and performance.

Debian 13 - Trixie I have been a Debian Testing user for longer than 10 years now (and I recommend it for non-server users), so I'm not usually keeping track of all the cool features arriving in the new Stable releases because I'm continuously receiving them through the Debian Testing rolling release. Nonetheless, as a Debian Developer I'm in a good position to point out the ones I can remember. I would also like other Debian Developers to do the same as I'm sure I would learn something new. The Debian 13 release notes contain a "What's new" section , which lists the first two items here and a few other things, in other words, take my list as an addition to the release notes. Debian 13 was released on 2025-08-09, and these are nice things you shouldn't miss in the new release, with a bonus one not tied to the Debian 13 release.

1) wcurl Have you ever had to download a file from your terminal using curl and didn't remember the parameters needed? I did. Nowadays you can use wcurl; "a command line tool which lets you download URLs without having to remember any parameters." Simply call wcurl with one or more URLs as parameters and it will download all of them in parallel, performing retries, choosing the correct output file name, following redirects, and more. Try it out:

wcurl example.com

wcurl comes installed as part of the curl package on Debian 13 and in any other distribution you can imagine, starting with curl 8.14.0. I've written more about wcurl in its release announcement and I've done a lightning talk presentation in DebConf24, which is linked in the release announcement.

2) HTTP/3 support in curl Debian has become the first stable Linux distribution to ship curl with support for HTTP/3. I've written about this in July 2024, when we first enabled it. Note that we first switched the curl CLI to GnuTLS, but then ended up releasing the curl CLI linked with OpenSSL (as support arrived later). Debian was the first Linux distro to enable it in the default build of the curl package, but Gentoo enabled it a few weeks earlier in their non-default flavor of the package, kudos to them! HTTP/3 is not used by default by the curl CLI, you have to enable it with --http3 or --http3-only. Try it out:

curl --http3 https://www.example.org
curl --http3-only https://www.example.org

3) systemd soft-reboot Starting with systemd v254, there's a new soft-reboot option, it's an userspace-only reboot, much faster than a full reboot if you don't need to reboot the kernel. You can read the announcement from the systemd v254 GitHub release Try it out:

# This will reboot your machine!
systemctl soft-reboot

4) apt --update Are you tired of being required to run sudo apt update just before sudo apt upgrade or sudo apt install $PACKAGE? So am I! The new --update option lets you do both things in a single command:

sudo apt --update upgrade
sudo apt --update install $PACKAGE

I love this, but it's still not yet where it should be, fingers crossed for a simple apt upgrade to behave like other package managers by updating its cache as part of the task, maybe in Debian 14? Try it out:

sudo apt upgrade --update
# The order doesn't matter
sudo apt --update upgrade

This is especially handy for container usage, where you have to update the apt cache before installing anything, for example:

podman run debian:stable bin/bash -c 'apt install --update -y curl'

5) powerline-go powerline-go is a powerline-style prompt written in Golang, so it's much more performant than its Python alternative powerline. powerline-style prompts are quite useful to show things like the current status of the git repo in your working directory, exit code of the previous command, presence of jobs in the background, whether or not you're in an ssh session, and more. Try it out:

sudo apt install powerline-go

Then add this to your .bashrc:

function _update_ps1()  
    PS1="$(/usr/bin/powerline-go -error $? -jobs $(jobs -p   wc -l))"

    # Uncomment the following line to automatically clear errors after showing
    # them once. This not only clears the error for powerline-go, but also for
    # everything else you run in that shell. Don't enable this if you're not
    # sure this is what you want.

    #set "?"
 

if [ "$TERM" != "linux" ] && [ -f "/usr/bin/powerline-go" ]; then
    PROMPT_COMMAND="_update_ps1; $PROMPT_COMMAND"
fi

Or this to .zshrc:

function powerline_precmd()  
    PS1="$(/usr/bin/powerline-go -error $? -jobs $ $ (%):%j :-0 )"

    # Uncomment the following line to automatically clear errors after showing
    # them once. This not only clears the error for powerline-go, but also for
    # everything else you run in that shell. Don't enable this if you're not
    # sure this is what you want.

    #set "?"
 

If you'd like to have your prompt start in a newline, like I have in the screenshot above, you just need to set -newline in the powerline-go invocation in your .bashrc/.zshrc.

6) Gnome System Monitor Extension Tips number 6 and 7 are for Gnome users. Gnome is now shipping a system monitor extension which lets you get a glance of the current load of your machine from the top bar. I've found this quite useful for machines where I'm required to install third-party monitoring software that tends to randomly consume more resources than it should. If I feel like my machine is struggling, I can quickly glance at its load to verify if it's getting overloaded by some process. The extension is not as complete as system-monitor-next, not showing temperatures or histograms, but at least it's officially part of Gnome, easy to install and supported by them. Try it out:

sudo apt install gnome-system-monitor gnome-shell-extension-manager

And then enable the extension from the "Extension Manager" application.

7) Gnome setting for battery charging profile After having to learn more about batteries in order to get into FPV drones, I've come to have a bigger appreciation for solutions that minimize the inevitable loss of capacity that accrues over time. There's now a "Battery Charging" setting (under the "Power") section which lets you choose between two different profiles: "Maximize Charge" and "Preserve Battery Health". On supported laptops, this setting is an easy way to set thresholds for when charging should start and stop, just like you could do it with the tlp package, but now from the Gnome settings. To increase the longevity of my laptop battery, I always keep it at "Preserve Battery Health" unless I'm traveling. What I would like to see next is support for choosing different "Power Modes" based on whether the laptop is plugged-in, and based on the battery charge percentage. There's a GNOME issue tracking this feature, but there's some pushback on whether this is the right thing to expose to users. In the meantime, there are some workarounds mentioned in that issue which people who really want this feature can follow. If you would like to learn more about batteries; Battery University is a great starting point, besides getting into FPV drones and being forced to handle batteries without a Battery Management System (BMS). And if by any chance this sparks your interest in FPV drones, Joshua Bardwell's YouTube channel is a great resource: @JoshuaBardwell.

8) Lazygit Emacs users are already familiar with the legendary magit; a terminal-based UI for git. Lazygit is an alternative for non-emacs users, you can integrate it with neovim or just use it directly. I'm still playing with lazygit and haven't integrated it into my workflows, but so far it has been a pleasant experience. You should check out the demos from the lazygit GitHub page. Try it out:

sudo apt install lazygit

And then call lazygit from within a git repository.

9) neovim neovim has been shipped in Debian since 2016, but upstream has been doing a lot of work to improve the experience out-of-the-box in the last couple of years. If you're a neovim poweruser, you're likely not installing it from the official repositories, but for those that are, Debian 13 comes with version 0.10.4, which brings the following improvements compared to the version in Debian 12:

• Treesitter support for C, Lua, Markdown, with the possibility of adding any other languages as needed;
• Better spellchecking due to treesitter integration (spellsitter);
• Mouse support enabled by default;
• Commenting support out-of-the-box; Check :h commenting for details, but the tl;dr is that you can use gcc to comment the current line and gc to comment the current selection.
• OSC52 support. Especially handy for those using neovim over an ssh connection, this protocol lets you copy something from within the neovim process into the clipboard of the machine you're using to connect through ssh. In other words, you can copy from neovim running in a host over ssh and paste it in the "outside" machine.

10) [Bonus] Running old Debian releases The bonus tip is not specific to the Debian 13 release, but something I've recently learned in the #debian-devel IRC channel. Did you know there are usable container images for all past Debian releases? I'm not talking "past" as in "some of the older releases", I'm talking past as in "literally every Debian release, including the very first one". Tianon Gravi "tianon" is the Debian Developer responsible for making this happen, kudos to him! There's a small gotcha that the releases Buzz (1.1) and Rex (1.2) require a 32-bit host, otherwise you will get the error Out of virtual memory!, but starting with Bo (1.3) all should work in amd64/arm64. Try it out:

sudo apt install podman

podman run -it docker.io/debian/eol:bo

Don't be surprised when noticing that apt/apt-get is not available inside the container, that's because apt first appeared in Debian Slink (2.1).

1. New backseat-signed tool to validate distributions source inputs
2. NixOS is not reproducible
3. Certificate vulnerabilities in F-Droid s fdroidserver
4. Website updates
5. Reproducible Builds and Insights from an Independent Verifier for Arch Linux
6. libntlm now releasing minimal source-only tarballs
7. Distribution work
8. Mailing list news
9. diffoscope
10. Upstream patches
11. reprotest
12. Reproducibility testing framework

New backseat-signed tool to validate distributions source inputs kpcyrd announced a new tool called backseat-signed, after:

I figured out a somewhat straight-forward way to check if a given git archive output is cryptographically claimed to be the source input of a given binary package in either Arch Linux or Debian (or both).

Elaborating more in their announcement post, kpcyrd writes:

I believe this to be the reproducible source tarball thing some people have been asking about. As explained in the README, I believe reproducing autotools-generated tarballs isn t worth everybody s time and instead a distribution that claims to build from source should operate on VCS snapshots instead of tarballs with 25k lines of pre-generated shell-script.

Indeed, many distributions packages already build from VCS snapshots, and this trend is likely to accelerate in response to the xz incident. The announcement led to a lengthy discussion on our mailing list, as well as shorter followup thread from kpcyrd about bootstrapping Autotools projects.

NixOS is not reproducible Morten Linderud posted an post on his blog this month, provocatively titled, NixOS is not reproducible . Although quickly admitting that his title is indeed clickbait , Morten goes on to clarify the precise guarantees and promises that NixOS provides its users. Later in the most, Morten mentions that he was motivated to write the post because:

I have heavily invested my free-time on this topic since 2017, and met some of the accomplishments we have had with Doesn t NixOS solve this? for just as long and I thought it would be of peoples interest to clarify[.]

Certificate vulnerabilities in F-Droid s fdroidserver In early April, Fay Stegerman announced a certificate pinning bypass vulnerability and Proof of Concept (PoC) in the F-Droid fdroidserver tools for managing builds, indexes, updates, and deployments for F-Droid repositories to the oss-security mailing list.

We observed that embedding a v1 (JAR) signature file in an APK with minSdk >= 24 will be ignored by Android/apksigner, which only checks v2/v3 in that case. However, since fdroidserver checks v1 first, regardless of minSdk, and does not verify the signature, it will accept a fake certificate and see an incorrect certificate fingerprint. [ ] We also realised that the above mentioned discrepancy between apksigner and androguard (which fdroidserver uses to extract the v2/v3 certificates) can be abused here as well. [ ]

Later on in the month, Fay followed up with a second post detailing a third vulnerability and a script that could be used to scan for potentially affected .apk files and mentioned that, whilst upstream had acknowledged the vulnerability, they had not yet applied any ameliorating fixes.

Website updates There were a number of improvements made to our website this month, including Chris Lamb updating the archive page to recommend -X and unzipping with TZ=UTC [ ] and adding Maven, Gradle, JDK and Groovy examples to the SOURCE_DATE_EPOCH page [ ]. In addition Jan Zerebecki added a new /contribute/opensuse/ page [ ] and Sertonix fixed the automatic RSS feed detection [ ][ ].

Reproducible Builds and Insights from an Independent Verifier for Arch Linux Joshua Drexel, Esther H nggi and Iy n M ndez Veiga of the School of Computer Science and Information Technology, Hochschule Luzern (HSLU) in Switzerland published a paper this month entitled Reproducible Builds and Insights from an Independent Verifier for Arch Linux. The paper establishes the context as follows:

Supply chain attacks have emerged as a prominent cybersecurity threat in recent years. Reproducible and bootstrappable builds have the potential to reduce such attacks significantly. In combination with independent, exhaustive and periodic source code audits, these measures can effectively eradicate compromises in the building process. In this paper we introduce both concepts, we analyze the achievements over the last ten years and explain the remaining challenges.

What is more, the paper aims to:

contribute to the reproducible builds effort by setting up a rebuilder and verifier instance to test the reproducibility of Arch Linux packages. Using the results from this instance, we uncover an unnoticed and security-relevant packaging issue affecting 16 packages related to Certbot [ ].

A PDF of the paper is available.

libntlm now releasing minimal source-only tarballs Simon Josefsson wrote on his blog this month that, going forward, the libntlm project will now be releasing what they call minimal source-only tarballs :

The XZUtils incident illustrate that tarballs with files that are not included in the git archive offer an opportunity to disguise malicious backdoors. [The] risk of hiding malware is not the only motivation to publish signed minimal source-only tarballs. With pre-generated content in tarballs, there is a risk that GNU/Linux distributions [ship] generated files coming from the tarball into the binary *.deb or *.rpm package file. Typically the person packaging the upstream project never realized that some installed artifacts was not re-built[.]

Simon s post goes into further details how this was achieved, and describes some potential caveats and counters some expected responses as well. A shorter version can be found in the announcement for the 1.8 release of libntlm.

Distribution work In Debian this month, Helmut Grohne filed a bug suggesting the removal of dh-buildinfo, a tool to generate and distribute .buildinfo-like files within binary packages. Note that this is distinct from the .buildinfo generation performed by dpkg-genbuildinfo. By contrast, the entirely optional dh-buildinfo generated a debian/buildinfo file that would be shipped within binary packages as /usr/share/doc/package/buildinfo_$arch.gz. Adrian Bunk recently asked about including source hashes in Debian s .buildinfo files, which prompted Guillem Jover to refresh some old patches to dpkg to make this possible, which revealed some quirks Vagrant Cascadian discovered when testing. In addition, 21 reviews of Debian packages were added, 22 were updated and 16 were removed this month adding to our knowledge about identified issues. A number issue types have been added, such as new random_temporary_filenames_embedded_by_mesonpy and timestamps_added_by_librime toolchain issues. In openSUSE, it was announced that their Factory distribution enabled bit-by-bit reproducible builds for almost all parts of the package. Previously, more parts needed to be ignored when comparing package files, but now only the signature needs to be deleted. In addition, Bernhard M. Wiedemann published theunreproduciblepackage as a proper .rpm package which it allows to better test tools intended to debug reproducibility. Furthermore, it was announced that Bernhard s work on a 100% reproducible openSUSE-based distribution will be funded by NLnet. He also posted another monthly report for his reproducibility work in openSUSE. In GNU Guix, Janneke Nieuwenhuizen submitted a patch set for creating a reproducible source tarball for Guix. That is to say, ensuring that make dist is reproducible when run from Git. [ ] Lastly, in Fedora, a new wiki page was created to propose a change to the distribution. Titled Changes/ReproduciblePackageBuilds , the page summarises itself as a proposal whereby A post-build cleanup is integrated into the RPM build process so that common causes of build irreproducibility in packages are removed, making most of Fedora packages reproducible.

Mailing list news On our mailing list this month:

• Continuing a thread started in March 2024 about the Arch Linux minimal container now being 100% reproducible, John Gilmore followed up with a post about the practical and philosophical distinctions of local vs. remote storage of the various artifacts needed to build packages.
• Chris Lamb asked the list which conferences readers are attending these days: After peak Covid and other industry-wide changes, conferences are no longer the must attend events they previously were especially in the area of software supply-chain security. In rough, practical terms, it seems harder to justify conference travel today than it did in mid-2019. The thread generated a number of responses which would be of interest to anyone planning travel in Q3 and Q4 of 2024.
• James Addison wrote to the list about a quirk in Git related to its core.autocrlf functionality, thus helpfully passing on a slightly off-topic and perhaps not of direct relevance to anyone on the list today note that might still be the kind of issue that is useful to be aware of if-and-when puzzling over unexpected git content / checksum issues (situations that I do expect people on this list encounter from time-to-time) .

diffoscope 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 263, 264 and 265 to Debian and made the following additional changes:

• Don t crash on invalid .zip files, even if we encounter their badness halfway through the file and not at the time of their initial opening. [ ]
• Prevent odt2txt tests from always being skipped due to an (impossibly) new version requirement. [ ]
• Avoid parens-in-parens in test skipping messages. [ ]
• Ensure that tests with >=-style version constraints actually print the tool name. [ ]

In addition, Fay Stegerman fixed a crash when there are (invalid) duplicate entries in .zip which was originally reported in Debian bug #1068705). [ ] Fay also added a user-visible note to a diff when there are duplicate entries in ZIP files [ ]. Lastly, Vagrant Cascadian added an external tool pointer for the zipdetails tool under GNU Guix [ ] and proposed updates to diffoscope in Guix as well [ ] which were merged as [264] [265], fixed a regression in test coverage and increased verbosity of the test suite[ ].

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:

• Chris Lamb:
  • #1068173 filed against pg-gvm.
  • #1068176 filed against goldendict-ng.
  • #1068372 filed against grokevt.
  • #1068374 filed against ttconv.
  • #1068375 filed against ludevit.
  • #1068795 filed against pympress.
  • #1069168 filed against sagemath-database-conway-polynomials.
  • #1069169 filed against gap-polymaking.
  • #1069663 filed against dub.
  • #1069709 filed against dpb.
  • #1069784 filed against python-itemloaders.
  • #1069822 filed against python-gvm.
• Bernhard M. Wiedemann:
  • metis (fix build with nocheck)
  • musique (fix a date-related issue)
  • orthanc-volview (fix an issue with mtimes and sorting)
  • go1.13, go1.14, go1.15 (fix a parallelism-related issue)
  • postfish (disable compile-time benchmarking)
  • geany/glfw (toolchain, random)
  • edk2/ovmf/tianocore (with Joey Li: fix a date-related issue)
  • dlib (report an issue with compile-time-CPU-detection)
  • lua-lmod (fix a date-related issue)
  • gitui (fix a date-related issue)
  • openssl-3 (report an issue with random output)
  • gcc14 (FTBFS-2038)
  • nebula (FTBFS-2027-11-11)
• Jan Zerebecki:
  • rpm (Support reproducible automatic rebuilds, etc.)
  • openSUSE-release-tools (Create changelog for generated package sources for SOURCE_DATE_EPOCH)
  • pesign-obs-integration (Create changelog for generated package sources for SOURCE_DATE_EPOCH)
  • openSUSE post-build-checks (Set SOURCE_DATE_EPOCH)
  • obs-build (Fix changelog timezone handling)
  • obs-service-tar_scm (When generating changelog from Git, create the file if it does not exist.)
• Thomas Goirand:
  • oslo.messaging (fix a hostname-related issue)

reprotest reprotest is our tool for building the same source code twice in different environments and then checking the binaries produced by each build for any differences. This month, reprotest version 0.7.27 was uploaded to Debian unstable) by Vagrant Cascadian who made the following additional changes:

• Enable specific number of CPUs using --vary=num_cpus.cpus=X. [ ]
• Consistently use 398 days for time variation, rather than choosing randomly each time. [ ]
• Disable builds of arch:any packages. [ ]
• Update the description for the build_path.path option in README.rst. [ ]
• Update escape sequences for compatibility with Python 3.12. (#1068853). [ ]
• Remove the generic upstream signing-key [ ] and update the packages signing key with the currently active team members [ ].
• Update the packaging Standards-Version to 4.7.0. [ ]

In addition, Holger Levsen fixed some spelling errors detected by the spellintian tool [ ] and Vagrant Cascadian updated reprotest in GNU Guix to 0.7.27.

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

• Debian-related changes:
  • Adjust for changed internal IP addresses at Codethink. [ ]
  • Automatically cleanup failed diffoscope user services if there are too many failures. [ ][ ]
  • Configure two new nodes at infomanik.cloud. [ ][ ]
  • Schedule Debian experimental even less. [ ][ ]
• Breakage detection:
  • Exclude currently building packages from breakage detection. [ ]
  • Be more noisy if diffoscope crashes. [ ]
  • Health check: provide clickable URLs in jenkins job log for failed pkg builds due to diffoscope crashes. [ ]
  • Limit graph to about the last 100 days of breakages only. [ ]
  • Fix all found files with bad permissions. [ ]
  • Prepare dealing with diffoscope timeouts. [ ]
  • Detect more cases of failure to debootstrap base system. [ ]
  • Include timestamps of failed job runs. [ ]
• Documentation updates:
  • Document how to access arm64 nodes at Codethink. [ ]
  • Document how to use infomaniak.cloud. [ ]
  • Drop notes about long stalled LeMaker HiKey960 boards sponsored by HPE and hosted at ETH. [ ]
  • Mention osuosl4 and osuosl5 and explain their usage. [ ]
  • Mention that some packages are built differently. [ ][ ]
  • Improve language in a comment. [ ]
  • Add more notes how to query resource usage from infomaniak.cloud. [ ]
• Node maintenance:
  • Add ionos4 and ionos14 to THANKS. [ ][ ][ ][ ][ ]
  • Deprecate Squid on ionos1 and ionos10. [ ]
  • Drop obsolete script to powercycle arm64 architecture nodes. [ ]
  • Update system_health_check for new proxy nodes. [ ]
• Misc changes:
  • Make the update_jdn.sh script more robust. [ ][ ]
  • Update my SSH public key. [ ]

In addition, Mattia Rizzolo added some new host details. [ ]

---

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

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

Changes in prrd version 0.0.6 (2024-03-06)

• The summary function has received several enhancements:
  • Extended summary is only running when failures are seen.
  • The summariseQueue function now displays an anticipated completion time and remaining duration.
  • The use of optional package foghorn has been refined, and refactored, when running summaries.
• The dequeueJobs.r scripts can receive a date argument, the date can be parse via anydate if anytime ins present.
• The enqueeJobs.r now considers skipped package when running 'addfailed' while ensuring selecting packages are still on CRAN.
• The CI setup has been updated (twice),
• Enqueing and dequing functions and scripts now support relative directories, updated documentation (#18 by Joshua Ulrich).

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

"We are not going to have another wretched empire while I am Patrician. We've only just got over the last one."

Steam Deck Rainbow: Treasure Map & Magic Frogs While I may be bubbly and chatty in everyday life, the stage isn t exactly my comfort zone (hallway talks are more my speed). But the journey of developing the AMD color management properties was so full of discoveries that I simply had to share the experience. Witnessing the fantastic work of Jeremy and Joshua bring it all to life on the Steam Deck OLED was like uncovering magical ingredients and whipping up something truly enchanting. For XDC 2023, we split our Rainbow journey into two talks. My focus, The Rainbow Treasure Map, explored the new color features we added to the Linux kernel driver, diving deep into the hardware capabilities of AMD/Steam Deck. Joshua then followed with The Rainbow Frogs and showed the breathtaking color magic released on Gamescope thanks to the power unlocked by the kernel driver s Steam Deck color properties.

Packing a Rainbow into 15 Minutes I had so much to tell, but a half-slot talk meant crafting a concise presentation. To squeeze everything into 15 minutes (and calm my pre-talk jitters a bit!), I drafted and practiced those slides and notes countless times. So grab your map, and let s embark on the Rainbow journey together! Intro: Hi, I m Melissa from Igalia and welcome to the Rainbow Treasure Map, a talk about advanced color management on Linux with AMD/SteamDeck. Useful links: First of all, if you are not used to the topic, you may find these links useful.

1. XDC 2022 - I m not an AMD expert, but - Melissa Wen
2. XDC 2022 - Is HDR Harder? - Harry Wentland
3. XDC 2022 Lightning - HDR Workshop Summary - Harry Wentland
4. Color management and HDR documentation for FOSS graphics - Pekka Paalanen et al.
5. Cinematic Color - 2012 SIGGRAPH course notes - Jeremy Selan
6. AMD Driver-specific Properties for Color Management on Linux (Part 1) - Melissa Wen

Context: When we talk about colors in the graphics chain, we should keep in mind that we have a wide variety of source content colorimetry, a variety of output display devices and also the internal processing. Users expect consistent color reproduction across all these devices. The userspace can use GPU-accelerated color management to get it. But this also requires an interface with display kernel drivers that is currently missing from the DRM/KMS framework. Since April, I ve been bothering the DRM community by sending patchsets from the work of me and Joshua to add driver-specific color properties to the AMD display driver. In parallel, discussions on defining a generic color management interface are still ongoing in the community. Moreover, we are still not clear about the diversity of color capabilities among hardware vendors. To bridge this gap, we defined a color pipeline for Gamescope that fits the latest versions of AMD hardware. It delivers advanced color management features for gamut mapping, HDR rendering, SDR on HDR, and HDR on SDR. AMD/Steam Deck hardware: AMD frequently releases new GPU and APU generations. Each generation comes with a DCN version with display hardware improvements. Therefore, keep in mind that this work uses the AMD Steam Deck hardware and its kernel driver. The Steam Deck is an APU with a DCN3.01 display driver, a DCN3 family. It s important to have this information since newer AMD DCN drivers inherit implementations from previous families but aldo each generation of AMD hardware may introduce new color capabilities. Therefore I recommend you to familiarize yourself with the hardware you are working on. The AMD display driver in the kernel space: It consists of three layers, (1) the DRM/KMS framework, (2) the AMD Display Manager, and (3) the AMD Display Core. We extended the color interface exposed to userspace by leveraging existing DRM resources and connecting them using driver-specific functions for color property management. Bridging DC color capabilities and the DRM API required significant changes in the color management of AMD Display Manager - the Linux-dependent part that connects the AMD DC interface to the DRM/KMS framework. The AMD DC is the OS-agnostic layer. Its code is shared between platforms and DCN versions. Examining this part helps us understand the AMD color pipeline and hardware capabilities, since the machinery for hardware settings and resource management are already there. The newest architecture for AMD display hardware is the AMD Display Core Next. In this architecture, two blocks have the capability to manage colors:

• Display Pipe and Plane (DPP) - for pre-blending adjustments;
• Multiple Pipe/Plane Combined (MPC) - for post-blending color transformations.

Let s see what we have in the DRM API for pre-blending color management. DRM plane color properties: This is the DRM color management API before blending. Nothing! Except two basic DRM plane properties: color_encoding and color_range for the input colorspace conversion, that is not covered by this work. In case you re not familiar with AMD shared code, what we need to do is basically draw a map and navigate there! We have some DRM color properties after blending, but nothing before blending yet. But much of the hardware programming was already implemented in the AMD DC layer, thanks to the shared code. Still both the DRM interface and its connection to the shared code were missing. That s when the search begins! AMD driver-specific color pipeline: Looking at the color capabilities of the hardware, we arrive at this initial set of properties. The path wasn t exactly like that. We had many iterations and discoveries until reached to this pipeline. The Plane Degamma is our first driver-specific property before blending. It s used to linearize the color space from encoded values to light linear values. We can use a pre-defined transfer function or a user lookup table (in short, LUT) to linearize the color space. Pre-defined transfer functions for plane degamma are hardcoded curves that go to a specific hardware block called DPP Degamma ROM. It supports the following transfer functions: sRGB EOTF, BT.709 inverse OETF, PQ EOTF, and pure power curves Gamma 2.2, Gamma 2.4 and Gamma 2.6. We also have a one-dimensional LUT. This 1D LUT has four thousand ninety six (4096) entries, the usual 1D LUT size in the DRM/KMS. It s an array of drm_color_lut that goes to the DPP Gamma Correction block. We also have now a color transformation matrix (CTM) for color space conversion. It s a 3x4 matrix of fixed points that goes to the DPP Gamut Remap Block. Both pre- and post-blending matrices were previously gone to the same color block. We worked on detaching them to clear both paths. Now each CTM goes on its own way. Next, the HDR Multiplier. HDR Multiplier is a factor applied to the color values of an image to increase their overall brightness. This is useful for converting images from a standard dynamic range (SDR) to a high dynamic range (HDR). As it can range beyond [0.0, 1.0] subsequent transforms need to use the PQ(HDR) transfer functions. And we need a 3D LUT. But 3D LUT has a limited number of entries in each dimension, so we want to use it in a colorspace that is optimized for human vision. It means in a non-linear space. To deliver it, userspace may need one 1D LUT before 3D LUT to delinearize content and another one after to linearize content again for blending. The pre-3D-LUT curve is called Shaper curve. Unlike Degamma TF, there are no hardcoded curves for shaper TF, but we can use the AMD color module in the driver to build the following shaper curves from pre-defined coefficients. The color module combines the TF and the user LUT values into the LUT that goes to the DPP Shaper RAM block. Finally, our rockstar, the 3D LUT. 3D LUT is perfect for complex color transformations and adjustments between color channels. 3D LUT is also more complex to manage and requires more computational resources, as a consequence, its number of entries is usually limited. To overcome this restriction, the array contains samples from the approximated function and values between samples are estimated by tetrahedral interpolation. AMD supports 17 and 9 as the size of a single-dimension. Blue is the outermost dimension, red the innermost. As mentioned, we need a post-3D-LUT curve to linearize the color space before blending. This is done by Blend TF and LUT. Similar to shaper TF, there are no hardcoded curves for Blend TF. The pre-defined curves are the same as the Degamma block, but calculated by the color module. The resulting LUT goes to the DPP Blend RAM block. Now we have everything connected before blending. As a conflict between plane and CRTC Degamma was inevitable, our approach doesn t accept that both are set at the same time. We also optimized the conversion of the framebuffer to wire encoding by adding support to pre-defined CRTC Gamma TF. Again, there are no hardcoded curves and TF and LUT are combined by the AMD color module. The same types of shaper curves are supported. The resulting LUT goes to the MPC Gamma RAM block. Finally, we arrived in the final version of DRM/AMD driver-specific color management pipeline. With this knowledge, you re ready to better enjoy the rainbow treasure of AMD display hardware and the world of graphics computing. With this work, Gamescope/Steam Deck embraces the color capabilities of the AMD GPU. We highlight here how we map the Gamescope color pipeline to each AMD color block. Future works: The search for the rainbow treasure is not over! The Linux DRM subsystem contains many hidden treasures from different vendors. We want more complex color transformations and adjustments available on Linux. We also want to expose all GPU color capabilities from all hardware vendors to the Linux userspace. Thanks Joshua and Harry for this joint work and the Linux DRI community for all feedback and reviews. The amazing part of this work comes in the next talk with Joshua and The Rainbow Frogs! Any questions?

---

References:

1. Slides of the talk The Rainbow Treasure Map.
2. Youtube video of the talk The Rainbow Treasure Map.
3. Patch series for AMD driver-specific color management properties (upstream Linux 6.8v).
4. SteamDeck/Gamescope color management pipeline
5. XDC 2023 website.
6. Igalia website.

TL;DR: This blog post explores the color capabilities of AMD hardware and how they are exposed to userspace through driver-specific properties. It discusses the different color blocks in the AMD Display Core Next (DCN) pipeline and their capabilities, such as predefined transfer functions, 1D and 3D lookup tables (LUTs), and color transformation matrices (CTMs). It also highlights the differences in AMD HW blocks for pre and post-blending adjustments, and how these differences are reflected in the available driver-specific properties. Overall, this blog post provides a comprehensive overview of the color capabilities of AMD hardware and how they can be controlled by userspace applications through driver-specific properties. This information is valuable for anyone who wants to develop applications that can take advantage of the AMD color management pipeline. Get a closer look at each hardware block s capabilities, unlock a wealth of knowledge about AMD display hardware, and enhance your understanding of graphics and visual computing. Stay tuned for future developments as we embark on a quest for GPU color capabilities in the ever-evolving realm of rainbow treasures.

---

Operating Systems can use the power of GPUs to ensure consistent color reproduction across graphics devices. We can use GPU-accelerated color management to manage the diversity of color profiles, do color transformations to convert between High-Dynamic-Range (HDR) and Standard-Dynamic-Range (SDR) content and color enhacements for wide color gamut (WCG). However, to make use of GPU display capabilities, we need an interface between userspace and the kernel display drivers that is currently absent in the Linux/DRM KMS API. In the previous blog post I presented how we are expanding the Linux/DRM color management API to expose specific properties of AMD hardware. Now, I ll guide you to the color features for the Linux/AMD display driver. We embark on a journey through DRM/KMS, AMD Display Manager, and AMD Display Core and delve into the color blocks to uncover the secrets of color manipulation within AMD hardware. Here we ll talk less about the color tools and more about where to find them in the hardware. We resort to driver-specific properties to reach AMD hardware blocks with color capabilities. These blocks display features like predefined transfer functions, color transformation matrices, and 1-dimensional (1D LUT) and 3-dimensional lookup tables (3D LUT). Here, we will understand how these color features are strategically placed into color blocks both before and after blending in Display Pipe and Plane (DPP) and Multiple Pipe/Plane Combined (MPC) blocks. That said, welcome back to the second part of our thrilling journey through AMD s color management realm!

AMD Display Driver in the Linux/DRM Subsystem: The Journey In my 2022 XDC talk I m not an AMD expert, but , I briefly explained the organizational structure of the Linux/AMD display driver where the driver code is bifurcated into a Linux-specific section and a shared-code portion. To reveal AMD s color secrets through the Linux kernel DRM API, our journey led us through these layers of the Linux/AMD display driver s software stack. It includes traversing the DRM/KMS framework, the AMD Display Manager (DM), and the AMD Display Core (DC) [1]. The DRM/KMS framework provides the atomic API for color management through KMS properties represented by struct drm_property. We extended the color management interface exposed to userspace by leveraging existing resources and connecting them with driver-specific functions for managing modeset properties. On the AMD DC layer, the interface with hardware color blocks is established. The AMD DC layer contains OS-agnostic components that are shared across different platforms, making it an invaluable resource. This layer already implements hardware programming and resource management, simplifying the external developer s task. While examining the DC code, we gain insights into the color pipeline and capabilities, even without direct access to specifications. Additionally, AMD developers provide essential support by answering queries and reviewing our work upstream. The primary challenge involved identifying and understanding relevant AMD DC code to configure each color block in the color pipeline. However, the ultimate goal was to bridge the DC color capabilities with the DRM API. For this, we changed the AMD DM, the OS-dependent layer connecting the DC interface to the DRM/KMS framework. We defined and managed driver-specific color properties, facilitated the transport of user space data to the DC, and translated DRM features and settings to the DC interface. Considerations were also made for differences in the color pipeline based on hardware capabilities.

Exploring Color Capabilities of the AMD display hardware Now, let s dive into the exciting realm of AMD color capabilities, where a abundance of techniques and tools await to make your colors look extraordinary across diverse devices. First, we need to know a little about the color transformation and calibration tools and techniques that you can find in different blocks of the AMD hardware. I borrowed some images from [2] [3] [4] to help you understand the information.

Predefined Transfer Functions (Named Fixed Curves): Transfer functions serve as the bridge between the digital and visual worlds, defining the mathematical relationship between digital color values and linear scene/display values and ensuring consistent color reproduction across different devices and media. You can learn more about curves in the chapter GPU Gems 3 - The Importance of Being Linear by Larry Gritz and Eugene d Eon. ITU-R 2100 introduces three main types of transfer functions:

• OETF: the opto-electronic transfer function, which converts linear scene light into the video signal, typically within a camera.
• EOTF: electro-optical transfer function, which converts the video signal into the linear light output of the display.
• OOTF: opto-optical transfer function, which has the role of applying the rendering intent .

AMD s display driver supports the following pre-defined transfer functions (aka named fixed curves):

• Linear/Unity: linear/identity relationship between pixel value and luminance value;
• Gamma 2.2, Gamma 2.4, Gamma 2.6: pure power functions;
• sRGB: 2.4: The piece-wise transfer function from IEC 61966-2-1:1999;
• BT.709: has a linear segment in the bottom part and then a power function with a 0.45 (~1/2.22) gamma for the rest of the range; standardized by ITU-R BT.709-6;
• PQ (Perceptual Quantizer): used for HDR display, allows luminance range capability of 0 to 10,000 nits; standardized by SMPTE ST 2084.

These capabilities vary depending on the hardware block, with some utilizing hardcoded curves and others relying on AMD s color module to construct curves from standardized coefficients. It also supports user/custom curves built from a lookup table.

1D LUTs (1-dimensional Lookup Table): A 1D LUT is a versatile tool, defining a one-dimensional color transformation based on a single parameter. It s very well explained by Jeremy Selan at GPU Gems 2 - Chapter 24 Using Lookup Tables to Accelerate Color Transformations It enables adjustments to color, brightness, and contrast, making it ideal for fine-tuning. In the Linux AMD display driver, the atomic API offers a 1D LUT with 4096 entries and 8-bit depth, while legacy gamma uses a size of 256.

3D LUTs (3-dimensional Lookup Table): These tables work in three dimensions red, green, and blue. They re perfect for complex color transformations and adjustments between color channels. It s also more complex to manage and require more computational resources. Jeremy also explains 3D LUT at GPU Gems 2 - Chapter 24 Using Lookup Tables to Accelerate Color Transformations

CTM (Color Transformation Matrices): Color transformation matrices facilitate the transition between different color spaces, playing a crucial role in color space conversion.

HDR Multiplier: HDR multiplier is a factor applied to the color values of an image to increase their overall brightness.

AMD Color Capabilities in the Hardware Pipeline First, let s take a closer look at the AMD Display Core Next hardware pipeline in the Linux kernel documentation for AMDGPU driver - Display Core Next In the AMD Display Core Next hardware pipeline, we encounter two hardware blocks with color capabilities: the Display Pipe and Plane (DPP) and the Multiple Pipe/Plane Combined (MPC). The DPP handles color adjustments per plane before blending, while the MPC engages in post-blending color adjustments. In short, we expect DPP color capabilities to match up with DRM plane properties, and MPC color capabilities to play nice with DRM CRTC properties. Note: here s the catch there are some DRM CRTC color transformations that don t have a corresponding AMD MPC color block, and vice versa. It s like a puzzle, and we re here to solve it!

AMD Color Blocks and Capabilities We can finally talk about the color capabilities of each AMD color block. As it varies based on the generation of hardware, let s take the DCN3+ family as reference. What s possible to do before and after blending depends on hardware capabilities describe in the kernel driver by struct dpp_color_caps and struct mpc_color_caps. The AMD Steam Deck hardware provides a tangible example of these capabilities. Therefore, we take SteamDeck/DCN301 driver as an example and look at the Color pipeline capabilities described in the file: driver/gpu/drm/amd/display/dcn301/dcn301_resources.c

/* Color pipeline capabilities */
dc->caps.color.dpp.dcn_arch = 1; // If it is a Display Core Next (DCN): yes. Zero means DCE.
dc->caps.color.dpp.input_lut_shared = 0;
dc->caps.color.dpp.icsc = 1; // Intput Color Space Conversion  (CSC) matrix.
dc->caps.color.dpp.dgam_ram = 0; // The old degamma block for degamma curve (hardcoded and LUT).  Gamma correction  is the new one.
dc->caps.color.dpp.dgam_rom_caps.srgb = 1; // sRGB hardcoded curve support
dc->caps.color.dpp.dgam_rom_caps.bt2020 = 1; // BT2020 hardcoded curve support (seems not actually in use)
dc->caps.color.dpp.dgam_rom_caps.gamma2_2 = 1; // Gamma 2.2 hardcoded curve support
dc->caps.color.dpp.dgam_rom_caps.pq = 1; // PQ hardcoded curve support
dc->caps.color.dpp.dgam_rom_caps.hlg = 1; // HLG hardcoded curve support
dc->caps.color.dpp.post_csc = 1; // CSC matrix
dc->caps.color.dpp.gamma_corr = 1; // New  Gamma Correction  block for degamma user LUT;
dc->caps.color.dpp.dgam_rom_for_yuv = 0;
dc->caps.color.dpp.hw_3d_lut = 1; // 3D LUT support. If so, it's always preceded by a shaper curve. 
dc->caps.color.dpp.ogam_ram = 1; //  Blend Gamma  block for custom curve just after blending
// 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; // Post-blending CTM (pre-blending CTM is always supported)
dc->caps.color.mpc.num_3dluts = pool->base.res_cap->num_mpc_3dlut; // Post-blending 3D LUT (preceded by shaper curve)
dc->caps.color.mpc.ogam_ram = 1; // Post-blending regamma.
// No pre-defined TF supported for regamma.
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; // Output CSC matrix.

I included some inline comments in each element of the color caps to quickly describe them, but you can find the same information in the Linux kernel documentation. See more in struct dpp_color_caps, struct mpc_color_caps and struct rom_curve_caps. Now, using this guideline, we go through color capabilities of DPP and MPC blocks and talk more about mapping driver-specific properties to corresponding color blocks.

DPP Color Pipeline: Before Blending (Per Plane) Let s explore the capabilities of DPP blocks and what you can achieve with a color block. The very first thing to pay attention is the display architecture of the display hardware: previously AMD uses a display architecture called DCE

• Display and Compositing Engine, but newer hardware follows DCN - Display Core Next.

The architectute is described by: dc->caps.color.dpp.dcn_arch

AMD Plane Degamma: TF and 1D LUT Described by: dc->caps.color.dpp.dgam_ram, dc->caps.color.dpp.dgam_rom_caps,dc->caps.color.dpp.gamma_corr AMD Plane Degamma data is mapped to the initial stage of the DPP pipeline. It is utilized to transition from scanout/encoded values to linear values for arithmetic operations. Plane Degamma supports both pre-defined transfer functions and 1D LUTs, depending on the hardware generation. DCN2 and older families handle both types of curve in the Degamma RAM block (dc->caps.color.dpp.dgam_ram); DCN3+ separate hardcoded curves and 1D LUT into two block: Degamma ROM (dc->caps.color.dpp.dgam_rom_caps) and Gamma correction block (dc->caps.color.dpp.gamma_corr), respectively. Pre-defined transfer functions:

• they are hardcoded curves (read-only memory - ROM);
• supported curves: sRGB EOTF, BT.709 inverse OETF, PQ EOTF and HLG OETF, Gamma 2.2, Gamma 2.4 and Gamma 2.6 EOTF.

The 1D LUT currently accepts 4096 entries of 8-bit. The data is interpreted as an array of struct drm_color_lut elements. Setting TF = Identity/Default and LUT as NULL means bypass. References:

• [PATCH v3 04/32] drm/amd/display: add driver-specific property for plane degamma LUT
• [PATCH v3 05/32] drm/amd/display: add plane degamma TF driver-specific property
• [PATCH v3 19/32] drm/amd/display: add plane degamma TF and LUT support

AMD Plane 3x4 CTM (Color Transformation Matrix) AMD Plane CTM data goes to the DPP Gamut Remap block, supporting a 3x4 fixed point (s31.32) matrix for color space conversions. The data is interpreted as a struct drm_color_ctm_3x4. Setting NULL means bypass. References:

• [PATCH v3 30/32] drm/amd/display: add plane CTM driver-specific property
• [PATCH v3 31/32] drm/amd/display: add plane CTM support
• [PATCH v3 32/32] drm/amd/display: Add 3x4 CTM support for plane CTM

AMD Plane Shaper: TF + 1D LUT Described by: dc->caps.color.dpp.hw_3d_lut The Shaper block fine-tunes color adjustments before applying the 3D LUT, optimizing the use of the limited entries in each dimension of the 3D LUT. On AMD hardware, a 3D LUT always means a preceding shaper 1D LUT used for delinearizing and/or normalizing the color space before applying a 3D LUT, so this entry on DPP color caps dc->caps.color.dpp.hw_3d_lut means support for both shaper 1D LUT and 3D LUT. Pre-defined transfer function enables delinearizing content with or without shaper LUT, where AMD color module calculates the resulted shaper curve. Shaper curves go from linear values to encoded values. If we are already in a non-linear space and/or don t need to normalize values, we can set a Identity TF for shaper that works similar to bypass and is also the default TF value. Pre-defined transfer functions:

• there is no DPP Shaper ROM. Curves are calculated by AMD color modules. Check calculate_curve() function in the file amd/display/modules/color/color_gamma.c.
• supported curves: Identity, sRGB inverse EOTF, BT.709 OETF, PQ inverse EOTF, HLG OETF, and Gamma 2.2, Gamma 2.4, Gamma 2.6 inverse EOTF.

The 1D LUT currently accepts 4096 entries of 8-bit. The data is interpreted as an array of struct drm_color_lut elements. When setting Plane Shaper TF (!= Identity) and LUT at the same time, the color module will combine the pre-defined TF and the custom LUT values into the LUT that s actually programmed. Setting TF = Identity/Default and LUT as NULL works as bypass. References:

• [PATCH v3 10/32] drm/amd/display: add plane shaper LUT and TF
• [PATCH v3 23/32] drm/amd/display: add plane shaper LUT support
• [PATCH v3 24/32] drm/amd/display: add plane shaper TF support

AMD Plane 3D LUT Described by: dc->caps.color.dpp.hw_3d_lut The 3D LUT in the DPP block facilitates complex color transformations and adjustments. 3D LUT is a three-dimensional array where each element is an RGB triplet. As mentioned before, the dc->caps.color.dpp.hw_3d_lut describe if DPP 3D LUT is supported. The AMD driver-specific property advertise the size of a single dimension via LUT3D_SIZE property. Plane 3D LUT is a blog property where the data is interpreted as an array of struct drm_color_lut elements and the number of entries is LUT3D_SIZE cubic. The array contains samples from the approximated function. Values between samples are estimated by tetrahedral interpolation The array is accessed with three indices, one for each input dimension (color channel), blue being the outermost dimension, red the innermost. This distribution is better visualized when examining the code in [RFC PATCH 5/5] drm/amd/display: Fill 3D LUT from userspace by Alex Hung:

+	for (nib = 0; nib < 17; nib++)  
+		for (nig = 0; nig < 17; nig++)  
+			for (nir = 0; nir < 17; nir++)  
+				ind_lut = 3 * (nib + 17*nig + 289*nir);
+
+				rgb_area[ind].red = rgb_lib[ind_lut + 0];
+				rgb_area[ind].green = rgb_lib[ind_lut + 1];
+				rgb_area[ind].blue = rgb_lib[ind_lut + 2];
+				ind++;
+			 
+		 
+	 

In our driver-specific approach we opted to advertise it s behavior to the userspace instead of implicitly dealing with it in the kernel driver. AMD s hardware supports 3D LUTs with 17-size or 9-size (4913 and 729 entries respectively), and you can choose between 10-bit or 12-bit. In the current driver-specific work we focus on enabling only 17-size 12-bit 3D LUT, as in [PATCH v3 25/32] drm/amd/display: add plane 3D LUT support:

+		/* Stride and bit depth are not programmable by API yet.
+		 * Therefore, only supports 17x17x17 3D LUT (12-bit).
+		 */
+		lut->lut_3d.use_tetrahedral_9 = false;
+		lut->lut_3d.use_12bits = true;
+		lut->state.bits.initialized = 1;
+		__drm_3dlut_to_dc_3dlut(drm_lut, drm_lut3d_size, &lut->lut_3d,
+					lut->lut_3d.use_tetrahedral_9,
+					MAX_COLOR_3DLUT_BITDEPTH);

A refined control of 3D LUT parameters should go through a follow-up version or generic API. Setting 3D LUT to NULL means bypass. References:

• [PATCH v3 09/32] drm/amd/display: add plane 3D LUT driver-specific properties
• [PATCH v3 25/32] drm/amd/display: add plane 3D LUT support

AMD Plane Blend/Out Gamma: TF + 1D LUT Described by: dc->caps.color.dpp.ogam_ram The Blend/Out Gamma block applies the final touch-up before blending, allowing users to linearize content after 3D LUT and just before the blending. It supports both 1D LUT and pre-defined TF. We can see Shaper and Blend LUTs as 1D LUTs that are sandwich the 3D LUT. So, if we don t need 3D LUT transformations, we may want to only use Degamma block to linearize and skip Shaper, 3D LUT and Blend. Pre-defined transfer function:

• there is no DPP Blend ROM. Curves are calculated by AMD color modules;
• supported curves: Identity, sRGB EOTF, BT.709 inverse OETF, PQ EOTF, HLG inverse OETF, and Gamma 2.2, Gamma 2.4, Gamma 2.6 EOTF.

The 1D LUT currently accepts 4096 entries of 8-bit. The data is interpreted as an array of struct drm_color_lut elements. If plane_blend_tf_property != Identity TF, AMD color module will combine the user LUT values with pre-defined TF into the LUT parameters to be programmed. Setting TF = Identity/Default and LUT to NULL means bypass. References:

• [PATCH v3 11/32] drm/amd/display: add plane blend
• [PATCH v3 27/32] drm/amd/display: add plane blend LUT and TF support

MPC Color Pipeline: After Blending (Per CRTC)

DRM CRTC Degamma 1D LUT The degamma lookup table (LUT) for converting framebuffer pixel data before apply the color conversion matrix. The data is interpreted as an array of struct drm_color_lut elements. Setting NULL means bypass. Not really supported. The driver is currently reusing the DPP degamma LUT block (dc->caps.color.dpp.dgam_ram and dc->caps.color.dpp.gamma_corr) for supporting DRM CRTC Degamma LUT, as explaning by [PATCH v3 20/32] drm/amd/display: reject atomic commit if setting both plane and CRTC degamma.

DRM CRTC 3x3 CTM Described by: dc->caps.color.mpc.gamut_remap It sets the current transformation matrix (CTM) apply to pixel data after the lookup through the degamma LUT and before the lookup through the gamma LUT. The data is interpreted as a struct drm_color_ctm. Setting NULL means bypass.

DRM CRTC Gamma 1D LUT + AMD CRTC Gamma TF Described by: dc->caps.color.mpc.ogam_ram After all that, you might still want to convert the content to wire encoding. No worries, in addition to DRM CRTC 1D LUT, we ve got a AMD CRTC gamma transfer function (TF) to make it happen. Possible TF values are defined by enum amdgpu_transfer_function. Pre-defined transfer functions:

• there is no MPC Gamma ROM. Curves are calculated by AMD color modules.
• supported curves: Identity, sRGB inverse EOTF, BT.709 OETF, PQ inverse EOTF, HLG OETF, and Gamma 2.2, Gamma 2.4, Gamma 2.6 inverse EOTF.

The 1D LUT currently accepts 4096 entries of 8-bit. The data is interpreted as an array of struct drm_color_lut elements. When setting CRTC Gamma TF (!= Identity) and LUT at the same time, the color module will combine the pre-defined TF and the custom LUT values into the LUT that s actually programmed. Setting TF = Identity/Default and LUT to NULL means bypass. References:

• [PATCH v3 12/32] drm/amd/display: add CRTC gamma TF driver-specific property
• [PATCH v3 15/32] drm/amd/display: add CRTC gamma TF support

Others

AMD CRTC Shaper and 3D LUT We have previously worked on exposing CRTC shaper and CRTC 3D LUT, but they were removed from the AMD driver-specific color series because they lack userspace case. CRTC shaper and 3D LUT works similar to plane shaper and 3D LUT but after blending (MPC block). The difference here is that setting (not bypass) Shaper and Gamma blocks together are not expected, since both blocks are used to delinearize the input space. In summary, we either set Shaper + 3D LUT or Gamma.

Input and Output Color Space Conversion There are two other color capabilities of AMD display hardware that were integrated to DRM by previous works and worth a brief explanation here. The DC Input CSC sets pre-defined coefficients from the values of DRM plane color_range and color_encoding properties. It is used for color space conversion of the input content. On the other hand, we have de DC Output CSC (OCSC) sets pre-defined coefficients from DRM connector colorspace properties. It is uses for color space conversion of the composed image to the one supported by the sink. References:

• [PATCH] amd/display/dc: Fix COLOR_ENCODING and COLOR_RANGE doing nothing for DCN20+
• [PATCH v6 00/13] Enable Colorspace connector property in amdgpu

The search for rainbow treasures is not over yet If you want to understand a little more about this work, be sure to watch Joshua and I presented two talks at XDC 2023 about AMD/Steam Deck colors on Gamescope:

• The rainbow treasure map: advanced color management on Linux with AMD/Steam Deck
• Rainbow Frogs: HDR + Color Management in Gamescope/SteamOS

In the time between the first and second part of this blog post, Uma Shashank and Chaitanya Kumar Borah published the plane color pipeline for Intel and Harry Wentland implemented a generic API for DRM based on VKMS support. We discussed these two proposals and the next steps for Color on Linux during the Color Management workshop at XDC 2023 and I briefly shared workshop results in the 2023 XDC lightning talk session. The search for rainbow treasures is not over yet! We plan to meet again next year in the 2024 Display Hackfest in Coru a-Spain (Igalia s HQ) to keep up the pace and continue advancing today s display needs on Linux. Finally, a HUGE thank you to everyone who worked with me on exploring AMD s color capabilities and making them available in userspace.

"Debian 30 years of collective intelligence" -Maqsuel Maqson Brazil

Pouso Alegre, Brazil

Macei , Brazil

Curitiba, Brazil

The cake is there. :) Honorary Debian Developers: Buzz, Jessie, and Woody welcome guests to this amazing party. Sao Carlos, state of Sao Paulo, Brazil Stickers, and Fliers, and Laptops, oh my! Belo Horizonte, Brazil Bras lia, Brazil Bras lia, Brazil Mexico 30 a os! A quick Selfie We do not encourage beverages on computing hardware, but this one is okay by us. Germany

30 years of love

The German Delegation is also looking for this dog who footed the bill for the party, then left mysteriously.

We took the party outside

We brought the party back inside at CCCamp Belgium

Cake and Diversity in Belgium El Salvador

Food and Fellowship in El Salvador South Africa

Debian is also very delicious!

All smiles waiting to eat the cake Reports Debian Day 30 years in Macei - Brazil Debian Day 30 years in S o Carlos - Brazil Debian Day 30 years in Pouso Alegre - Brazil Debian Day 30 years in Belo Horizonte - Brazil Debian Day 30 years in Curitiba - Brazil Debian Day 30 years in Bras lia - Brazil Debian Day 30 years online in Brazil Articles & Blogs Happy Debian Day - going 30 years strong - Liam Dawe Debian Turns 30 Years Old, Happy Birthday! - Marius Nestor 30 Years of Stability, Security, and Freedom: Celebrating Debian s Birthday - Bobby Borisov Happy 30th Birthday, Debian! - Claudio Kuenzier Debian is 30 and Sgt Pepper Is at Least Ninetysomething - Christine Hall Debian turns 30! -Corbet Thirty years of Debian! - Lennart Hengstmengel Debian marks three decades as 'Universal Operating System' - Sam Varghese Debian Linux Celebrates 30 Years Milestone - Joshua James 30 years on, Debian is at the heart of the world's most successful Linux distros - Liam Proven Looking Back on 30 Years of Debian - Maya Posch Cheers to 30 Years of Debian: A Journey of Open Source Excellence - arindam Discussions and Social Media Debian Celebrates 30 Years - Source: News YCombinator Brand-new Linux release, which I'm calling the Debian ... Source: News YCombinator Comment: Congrats @debian !!! Happy Birthday! Thank you for becoming a cornerstone of the #opensource world. Here's to decades of collaboration, stability & #software #freedom -openSUSELinux via X (formerly Twitter) Comment: Today we #celebrate the 30th birthday of #Debian, one of the largest and most important cornerstones of the #opensourcecommunity. For this we would like to thank you very much and wish you the best for the next 30 years! Source: X (Formerly Twitter -TUXEDOComputers via X (formerly Twitter) Happy Debian Day! - Source: Reddit.com Video The History of Debian The Beginning - Source: Linux User Space Debian Celebrates 30 years -Source: Lobste.rs Video Debian At 30 and No More Distro Hopping! - LWDW388 - Source: LinuxGameCast Debian Celebrates 30 years! - Source: Debian User Forums Debian Celebrates 30 years! - Source: Linux.org

TL;DR: Color is a visual perception. Human eyes can detect a broader range of colors than any devices in the graphics chain. Since each device can generate, capture or reproduce a specific subset of colors and tones, color management controls color conversion and calibration across devices to ensure a more accurate and consistent color representation. We can expose a GPU-accelerated display color management pipeline to support this process and enhance results, and this is what we are doing on Linux to improve color management on Gamescope/SteamDeck. Even with the challenges of being external developers, we have been working on mapping AMD GPU color capabilities to the Linux kernel color management interface, which is a combination of DRM and AMD driver-specific color properties. This more extensive color management pipeline includes pre-defined Transfer Functions, 1-Dimensional LookUp Tables (1D LUTs), and 3D LUTs before and after the plane composition/blending.

---

The study of color is well-established and has been explored for many years. Color science and research findings have also guided technology innovations. As a result, color in Computer Graphics is a very complex topic that I m putting a lot of effort into becoming familiar with. I always find myself rereading all the materials I have collected about color space and operations since I started this journey (about one year ago). I also understand how hard it is to find consensus on some color subjects, as exemplified by all explanations around the 2015 online viral phenomenon of The Black and Blue Dress. Have you heard about it? What is the color of the dress for you? So, taking into account my skills with colors and building consensus, this blog post only focuses on GPU hardware capabilities to support color management :-D If you want to learn more about color concepts and color on Linux, you can find useful links at the end of this blog post.

Linux Kernel, show me the colors ;D DRM color management interface only exposes a small set of post-blending color properties. Proposals to enhance the DRM color API from different vendors have landed the subsystem mailing list over the last few years. On one hand, we got some suggestions to extend DRM post-blending/CRTC color API: DRM CRTC 3D LUT for R-Car (2020 version); DRM CRTC 3D LUT for Intel (draft - 2020); DRM CRTC 3D LUT for AMD by Igalia (v2 - 2023); DRM CRTC 3D LUT for R-Car (v2 - 2023). On the other hand, some proposals to extend DRM pre-blending/plane API: DRM plane colors for Intel (v2 - 2021); DRM plane API for AMD (v3 - 2021); DRM plane 3D LUT for AMD - 2021. Finally, Simon Ser sent the latest proposal in May 2023: Plane color pipeline KMS uAPI, from discussions in the 2023 Display/HDR Hackfest, and it is still under evaluation by the Linux Graphics community. All previous proposals seek a generic solution for expanding the API, but many seem to have stalled due to the uncertainty of matching well the hardware capabilities of all vendors. Meanwhile, the use of AMD color capabilities on Linux remained limited by the DRM interface, as the DCN 3.0 family color caps and mapping diagram below shows the Linux/DRM color interface without driver-specific color properties [*]: Bearing in mind that we need to know the variety of color pipelines in the subsystem to be clear about a generic solution, we decided to approach the issue from a different perspective and worked on enabling a set of Driver-Specific Color Properties for AMD Display Drivers. As a result, I recently sent another round of the AMD driver-specific color mgmt API. For those who have been following the AMD driver-specific proposal since the beginning (see [RFC][V1]), the main new features of the latest version [v2] are the addition of pre-blending Color Transformation Matrix (plane CTM) and the differentiation of Pre-defined Transfer Functions (TF) supported by color blocks. For those who just got here, I will recap this work in two blog posts. This one describes the current status of the AMD display driver in the Linux kernel/DRM subsystem and what changes with the driver-specific properties. In the next post, we go deeper to describe the features of each color block and provide a better picture of what is available in terms of color management for Linux.

The Linux kernel color management API and AMD hardware color capabilities Before discussing colors in the Linux kernel with AMD hardware, consider accessing the Linux kernel documentation (version 6.5.0-rc5). In the AMD Display documentation, you will find my previous work documenting AMD hardware color capabilities and the Color Management Properties. It describes how AMD Display Manager (DM) intermediates requests between the AMD Display Core component (DC) and the Linux/DRM kernel interface for color management features. It also describes the relevant function to call the AMD color module in building curves for content space transformations. A subsection also describes hardware color capabilities and how they evolve between versions. This subsection, DC Color Capabilities between DCN generations, is a good starting point to understand what we have been doing on the kernel side to provide a broader color management API with AMD driver-specific properties.

Why do we need more kernel color properties on Linux? Blending is the process of combining multiple planes (framebuffers abstraction) according to their mode settings. Before blending, we can manage the colors of various planes separately; after blending, we have combined those planes in only one output per CRTC. Color conversions after blending would be enough in a single-plane scenario or when dealing with planes in the same color space on the kernel side. Still, it cannot help to handle the blending of multiple planes with different color spaces and luminance levels. With plane color management properties, userspace can get a more accurate representation of colors to deal with the diversity of color profiles of devices in the graphics chain, bring a wide color gamut (WCG), convert High-Dynamic-Range (HDR) content to Standard-Dynamic-Range (SDR) content (and vice-versa). With a GPU-accelerated display color management pipeline, we can use hardware blocks for color conversions and color mapping and support advanced color management. The current DRM color management API enables us to perform some color conversions after blending, but there is no interface to calibrate input space by planes. Note that here I m not considering some workarounds in the AMD display manager mapping of DRM CRTC de-gamma and DRM CRTC CTM property to pre-blending DC de-gamma and gamut remap block, respectively. So, in more detail, it only exposes three post-blending features:

• DRM CRTC de-gamma: used to convert the framebuffer s colors to linear gamma;
• DRM CRTC CTM: used for color space conversion;
• DRM CRTC gamma: used to convert colors to the gamma space of the connected screen.

AMD driver-specific color management interface We can compare the Linux color management API with and without the driver-specific color properties. From now, we denote driver-specific properties with the AMD prefix and generic properties with the DRM prefix. For visual comparison, I bring the DCN 3.0 family color caps and mapping diagram closer and present it here again: Mixing AMD driver-specific color properties with DRM generic color properties, we have a broader Linux color management system with the following features exposed by properties in the plane and CRTC interface, as summarized by this updated diagram: The blocks highlighted by red lines are the new properties in the driver-specific interface developed by me (Igalia) and Joshua (Valve). The red dashed lines are new links between API and AMD driver components implemented by us to connect the Linux/DRM interface to AMD hardware blocks, mapping components accordingly. In short, we have the following color management properties exposed by the DRM/AMD display driver:

• Pre-blending - AMD Display Pipe and Plane (DPP):
  • AMD plane de-gamma: 1D LUT and pre-defined transfer functions; used to linearize the input space of a plane;
  • AMD plane CTM: 3x4 matrix; used to convert plane color space;
  • AMD plane shaper: 1D LUT and pre-defined transfer functions; used to delinearize and/or normalize colors before applying 3D LUT;
  • AMD plane 3D LUT: 17x17x17 size with 12 bit-depth; three dimensional lookup table used for advanced color mapping;
  • AMD plane blend/out gamma: 1D LUT and pre-defined transfer functions; used to linearize back the color space after 3D LUT for blending.
• Post-blending - AMD Multiple Pipe/Plane Combined (MPC):
  • DRM CRTC de-gamma: 1D LUT (can t be set together with plane de-gamma);
  • DRM CRTC CTM: 3x3 matrix (remapped to post-blending matrix);
  • DRM CRTC gamma: 1D LUT + AMD CRTC gamma TF; added to take advantage of driver pre-defined transfer functions;

Note: You can find more about AMD display blocks in the Display Core Next (DCN) - Linux kernel documentation, provided by Rodrigo Siqueira (Linux/AMD display developer) in a 2021-documentation series. In the next post, I ll revisit this topic, explaining display and color blocks in detail.

How did we get a large set of color features from AMD display hardware? So, looking at AMD hardware color capabilities in the first diagram, we can see no post-blending (MPC) de-gamma block in any hardware families. We can also see that the AMD display driver maps CRTC/post-blending CTM to pre-blending (DPP) gamut_remap, but there is post-blending (MPC) gamut_remap (DRM CTM) from newer hardware versions that include SteamDeck hardware. You can find more details about hardware versions in the Linux kernel documentation/AMDGPU Product Information. I needed to rework these two mappings mentioned above to provide pre-blending/plane de-gamma and CTM for SteamDeck. I changed the DC mapping to detach stream gamut remap matrixes from the DPP gamut remap block. That means mapping AMD plane CTM directly to DPP/pre-blending gamut remap block and DRM CRTC CTM to MPC/post-blending gamut remap block. In this sense, I also limited plane CTM properties to those hardware versions with MPC/post-blending gamut_remap capabilities since older versions cannot support this feature without clashes with DRM CRTC CTM. Unfortunately, I couldn t prevent conflict between AMD plane de-gamma and DRM plane de-gamma since post-blending de-gamma isn t available in any AMD hardware versions until now. The fact is that a post-blending de-gamma makes little sense in the AMD color pipeline, where plane blending works better in a linear space, and there are enough color blocks to linearize content before blending. To deal with this conflict, the driver now rejects atomic commits if users try to set both AMD plane de-gamma and DRM CRTC de-gamma simultaneously. Finally, we had no other clashes when enabling other AMD driver-specific color properties for our use case, Gamescope/SteamDeck. Our main work for the remaining properties was understanding the data flow of each property, the hardware capabilities and limitations, and how to shape the data for programming the registers - AMD color block capabilities (and limitations) are the topics of the next blog post. Besides that, we fixed some driver bugs along the way since it was the first Linux use case for most of the new color properties, and some behaviors are only exposed when exercising the engine. Take a look at the Gamescope/Steam Deck Color Pipeline[**], and see how Gamescope uses the new API to manage color space conversions and calibration (please click on the image for a better view): In the next blog post, I ll describe the implementation and technical details of each pre- and post-blending color block/property on the AMD display driver. * Thank Harry Wentland for helping with diagrams, color concepts and AMD capabilities. ** Thank Joshua Ashton for providing and explaining Gamescope/Steam Deck color pipeline. *** Thanks to the Linux Graphics community - explicitly Harry, Joshua, Pekka, Simon, Sebastian, Siqueira, Alex H. and Ville - to all the learning during this Linux DRM/AMD color journey. Also, Carlos and Tomas for organizing the 2023 Display/HDR Hackfest where we have a great and immersive opportunity to discuss Color & HDR on Linux.

Useful Links

1. Cinematic Color - 2012 SIGGRAPH course notes by Jeremy Selan: an introduction to color science, concepts and pipelines.
2. Color management and HDR documentation for FOSS graphics by Pekka Paalanen: documentation and useful links on applying color concepts to the Linux graphics stack.
3. HDR in Linux by Jeremy Cline: a blog post exploring color concepts for HDR support on Linux.
4. Methods for conversion of high dynamic range content to standard dynamic range content and vice-versa by ITU-R: guideline for conversions between HDR and SDR contents.
5. Using Lookup Tables to Accelerate Color Transformations by Jeremy Selan: Nvidia blog post about Lookup Tables on color management.
6. The Importance of Being Linear by Larry Gritz and Eugene d Eon: Nvidia blog post about gamma and color conversions.

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

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

dang::intradayMarketMonitor()

Changes in version 0.0.13 (2021-02-17)

• New function intradayMarketMonitor based on an earlier gist-posted snippet by Josh Ulrich.
• The CI setup was generalized as a test for 'r-ci' and is used essentially unchanged with three different providers.

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

Changes in Rcpp version 1.0.4 (2020-03-13)

• Changes in Rcpp API:
  • Safer Rcpp_list*, Rcpp_lang* and Function.operator() (Romain in #1014, #1015).
  • A number of #nocov markers were added (Dirk in #1036, #1042 and #1044).
  • Finalizer calls clear external pointer first (Kirill M ller and Dirk in #1038).
  • Scalar operations with a rhs matrix no longer change the matrix value (Qiang in #1040 fixing (again) #365).
  • Rcpp::exception and Rcpp::stop are now more thread-safe (Joshua Pritikin in #1043).
• Changes in Rcpp Attributes:
  • The cppFunction helper now deals correctly with mulitple depends arguments (TJ McKinley in #1016 fixing #1017).
  • Invisible return objects are now supported via new option (Kun Ren in #1025 fixing #1024).
  • Unavailable packages referred to in LinkingTo are now reported (Dirk in #1027 fixing #1026).
  • The sourceCpp function can now create a debug DLL on Windows (Dirk in #1037 fixing #1035).
• Changes in Rcpp Documentation:
  • The .github/ directory now has more explicit guidance on contributing, issues, and pull requests (Dirk).
  • The Rcpp Attributes vignette describe the new invisible return object option (Kun Ren in #1025).
  • Vignettes are now included as pre-made pdf files (Dirk in #1029)
  • The Rcpp FAQ has a new entry on the recommended importFrom directive (Dirk in #1031 fixing #1030).
  • The bib file for the vignette was once again updated to current package versions (Dirk).
• Changes in Rcpp Deployment:
  • Added unit test to check if C++ version remains remains aligned with the package number (Dirk in #1022 fixing #1021).
  • The unit test system was switched to tinytest (Dirk in #1028, #1032, #1033).

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

## plotOBOS -- displaying overbough/oversold as eg in Bespoke's plots
##
## Copyright (C) 2010 - 2017  Dirk Eddelbuettel
##
## This is free software: you can redistribute it and/or modify it
## under the terms of the GNU General Public License as published by
## the Free Software Foundation, either version 2 of the License, or
## (at your option) any later version.
suppressMessages(library(quantmod))     # for getSymbols(), brings in xts too
suppressMessages(library(TTR))          # for various moving averages
plotOBOS <- function(symbol, n=50, type=c("sma", "ema", "zlema"),
                     years=1, blue=TRUE, current=TRUE, title=symbol,
                     ticks=TRUE, axes=TRUE)  
    today <- Sys.Date()
    if (class(symbol) == "character")  
        X <- getSymbols(symbol, from=format(today-365*years-2*n), auto.assign=FALSE)
        x <- X[,6]                          # use Adjusted
      else if (inherits(symbol, "zoo"))  
        x <- X <- as.xts(symbol)
        current <- FALSE                # don't expand the supplied data
     
    n <- min(nrow(x)/3, 50)             # as we may not have 50 days
    sub <- ""
    if (current)  
        xx <- getQuote(symbol)
        xt <- xts(xx$Last, order.by=as.Date(xx$ Trade Time ))
        colnames(xt) <- paste(symbol, "Adjusted", sep=".")
        x <- rbind(x, xt)
        sub <- paste("Last price: ", xx$Last, " at ",
                     format(as.POSIXct(xx$ Trade Time ), "%H:%M"), sep="")
     
    type <- match.arg(type)
    xd <- switch(type,                  # compute xd as the central location via selected MA smoother
                 sma = SMA(x,n),
                 ema = EMA(x,n),
                 zlema = ZLEMA(x,n))
    xv <- runSD(x, n)                   # compute xv as the rolling volatility
    strt <- paste(format(today-365*years), "::", sep="")
    x  <- x[strt]                       # subset plotting range using xts' nice functionality
    xd <- xd[strt]
    xv <- xv[strt]
    xyd <- xy.coords(.index(xd),xd[,1]) # xy coordinates for direct plot commands
    xyv <- xy.coords(.index(xv),xv[,1])
    n <- length(xyd$x)
    xx <- xyd$x[c(1,1:n,n:1)]           # for polygon(): from first point to last and back
    if (blue)  
        blues5 <- c("#EFF3FF", "#BDD7E7", "#6BAED6", "#3182BD", "#08519C") # cf brewer.pal(5, "Blues")
        fairlylight <<- rgb(189/255, 215/255, 231/255, alpha=0.625) # aka blues5[2]
        verylight <<- rgb(239/255, 243/255, 255/255, alpha=0.625) # aka blues5[1]
        dark <<- rgb(8/255, 81/255, 156/255, alpha=0.625) # aka blues5[5]
        ## buglet in xts 0.10-0 requires the <<- here
      else  
        fairlylight <<- rgb(204/255, 204/255, 204/255, alpha=0.5)  # two suitable grays, alpha-blending at 50%
        verylight <<- rgb(242/255, 242/255, 242/255, alpha=0.5)
        dark <<- 'black'
     
    plot(x, ylim=range(range(x, xd+2*xv, xd-2*xv, na.rm=TRUE)), main=title, sub=sub, 
         major.ticks=ticks, minor.ticks=ticks, axes=axes) # basic xts plot setup
    addPolygon(xts(cbind(xyd$y+xyv$y, xyd$y+2*xyv$y), order.by=index(x)), on=1, col=fairlylight)  # upper
    addPolygon(xts(cbind(xyd$y-xyv$y, xyd$y+1*xyv$y), order.by=index(x)), on=1, col=verylight)    # center
    addPolygon(xts(cbind(xyd$y-xyv$y, xyd$y-2*xyv$y), order.by=index(x)), on=1, col=fairlylight)  # lower
    lines(xd, lwd=2, col=fairlylight)   # central smooted location
    lines(x, lwd=3, col=dark)           # actual price, thicker
 

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

source(file="https://raw.githubusercontent.com/dirkschumacher/thankr/master/R/shoulders.R")
format_pkg_df <- function(df)   # non-tibblyverse variant
    tb <- table(df[,2])
    od <- order(tb, decreasing=TRUE)
    ndf <- data.frame(maint=names(tb)[od], npkgs=as.integer(tb[od]))
    colpkgs <- function(m, df)   paste(df[ df$maintainer == m, "pkg_name"], collapse=",")  
    ndf[, "pkg"] <- sapply(ndf$maint, colpkgs, df)
    ndf
 

R> shoulders()  ## by Dirk Schumacher, with small modifications
                               maint npkgs                                                                 pkg
1 R Core Team <R-core@r-project.org>     9 compiler,graphics,tools,utils,grDevices,stats,datasets,methods,base
2 Dirk Eddelbuettel <edd@debian.org>     4                                  RcppTOML,Rcpp,RApiDatetime,anytime
3  Matt Dowle <mattjdowle@gmail.com>     1                                                          data.table
R> 

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

Changes in RApiDatetime version 0.0.2 (2017-03-25)

• Windows support has added (Josh Ulrich in #1)

Changes in RApiDatetime version 0.0.1 (2017-03-23)

• Initial release with six accessible functions

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

• Holger proposed a hackathon with various possible dates -- please reply with your preferred dates!
• "Reproducible builds: Status update" CfP submitted for Debconf17 in Montreal.

• pnmixer (Chris Lamb)
• cloud-sptheme (Chris Lamb)
• python-hypothesis (Chris Lamb)
• cython (Jelmer Vernoo )

• #854332 filed against cloud-sptheme.
• #854512 filed against ftpcopy.
• #854549 filed against python-hypothesis.

• #854492 filed against xlsx2csv.
• #854541 filed against sogo.

• #854293 filed against manpages-tr.
• #854294 filed against regina-rexx.
• #854362 filed against fonts-uralic.

• randomness_in_swf_files_generated_by_as3compile
• randomness_in_t3g_files_generated_tslmendian
• absolute_build_paths_in_dot_packlist_file_generated_by_perl_extutils_packlist
• formatdb_from_ncbi_blastplus_captures_build_time
• timestamp_and_build_path_captured_by_python_cheetah

• build_id_differences_only

• Chris Lamb (7)
• gregory bahde (1)

• Chris Lamb:
  • New features:
    • Add --exclude option. (Closes: #854783)
    • Apply --max-report-size to --text reports. (Closes: #851147)
    • Add a machine-readable JSON output format. (Closes: #850791)
    • Show results from debugging packages last (Closes: #820427)
    • Specify lang="en" in HTML output. (re. #849411)
  • Bug fixes:
    • Fix errors when comparing directories with non-directories. (Closes: #835641)
    • Clean all temp files in signal handler thread instead of attempting to bubble exception back to the main thread. (Closes: #852013)
    • Correct logic of module_exists, ensuring we correctly skip tests when python3-debian is not installed. (Closes: #854745)
    • Extract archive members using an auto-incrementing integer, avoiding the need to sanitise filenames. (Closes: #854723)
    • Importing submodules (ie. parent.child) will attempt to import parent so we must catch that. (Closes: #854670)
    • Add missing Recommends for comparators. (Closes: #854655)
    • Device and RPM fallback comparisons needs xxd due to fixtures. (Closes: #854593)
    • Fix behaviour of setting report maximums to zero (ie. no limits)
  • Misc:
    • Don't uselessly run xxd(1) on non-directories.
    • Add .travis.yml from http://travis.debian.net.
    • Use diffoscope.tempfiles over tempfile.TemporaryDirectory to ensure correct cleanup at end of diffoscope run.
  • Tests:
    • Smoke test --progress output.
    • Test the --status-fd output.
    • Move many tests to use new @skip_unless_module_exists decorator.
    • Show local variables in pytest tracebacks.
• Mattia Rizzolo:
  • No need to do complex string formatting just to convert an integer in a string
• Holger Levsen:
  • README: Keep history, explain this was started in Debian.
• Ximin Luo:
  • Better way of performing the entry name sanitisation
  • Simplify call to subprocess.Popen
  • Remove pointless use of a thread
• Brett Smith:
  • diffoscope.diff: Improve FIFO writing robustness.

• Print log entry when fixing a file. (Closes: #777239)
• dh_strip_nondeterminism: Use error() from Dh_Lib.pm over manual die().

• Chris Lamb:
  • Drop raw_text fields now; we've moved them to default_storage (S3)

• Joshua Lock:
  • Link to Yocto Project on projects page