blog: add 6.17 progress report

content/blog/2025/10/24-progress-report-6-17.md

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+date = "2025-10-24T10:30:00+10:00"
+draft = false
+title = "Progress Report: Linux 6.17"
+slug = "progress-report-6-17"
+author = "James Calligeros"
++++
+
+Another upstream kernel release means it must be time for a progress report!
+
+## The patches keep coming
+As always, upstreaming continues. The highlight of this cycle is finally landing
+the SMC core driver, after discussions on the mailing list going all the way back
+to 2022! Along with the core driver, drivers for the SMC's GPIO controller and
+reboot controller have also been merged. This allows devices which are already
+upstream to reboot gracefully, and lays the groundwork for enabling WiFi and
+Bluetooth upstream.
+
+Also merged for 6.17 are a few Devicetree changes which lay the groundwork for
+upstreaming GPU support. While these are ultimately a small piece of the whole GPU
+puzzle, they are very important. The Devicetree schema determines how the GPU kernel
+driver gets the information it needs from firmware to properly control the GPU. Now
+that this is stable and the properties merged into the upstream Devicetrees, we
+can be reasonably confident that the parts of the GPU driver that interact with
+the Devicetree won't require substantial changes.
+
+Work is also progressing on getting more SMC functionality upstream. The hardware
+monitoring, lid switch and power button, and RTC drivers are all close to being
+merged, with just a few minor issues left to address.
+
+Apple Silicon SoCs place peripheral devices and IP blocks (like the display
+controller) behind an IOMMU called DART. These act as a sort of firewall for peripherals,
+preventing them from accessing memory addresses that they shouldn't. The DARTs on the
+M2 Pro, Max and Ultra (T602x) SoCs are *mostly* compatible with those found on
+the base M2, with one caveat: they support a larger address space. Supporting this
+required implementing four-level pagetables in the DART driver. This change, along
+with the Devicetrees for all M2 Pro, Max and Ultra based devices have now been merged,
+and are available in v6.18-rc1!
+
+And of course, there are the USB patches. It seems like just about everyone's
+been following these on the mailing list, so it would be remiss not to mention
+them. Anyway, moving on.
+
+## m1n1's starting to Rust
+Slowing down the kernel treadmill has enabled us to finally start taking a look
+at other parts of the stack, and we've been making some important (and long
+overdue) changes to m1n1.
+
+For a while now, the recommended method for installing non-Fedora distros has
+been to use the "UEFI Only" installer option, then boot the preferred distro's
+Asahi installation media from USB. However, it has been quite some time since
+this installation option was updated, and the m1n1/U-Boot/Devicetree bundle it was
+installing was over two years old. A lot has changed in that time, and it turned
+out that this bundle was not capable of booting modern Asahi kernels. Oops.
+
+To fix this, Janne has added a [CI pipeline](https://github.com/AsahiLinux/m1n1/actions/workflows/installer.yml)
+to the m1n1 repo that will automatically build the UEFI bundle for us. With
+this step automated, it is now trivial to upload the resulting artefact to our CDN
+and point the Asahi Installer to it. The update cadence should now be a lot more
+frequent than biennially!
+
+We have also released [m1n1 v1.5.2](https://github.com/AsahiLinux/m1n1/releases/tag/v1.5.2).
+This release is fairly uncontroversial, with the main changes being adding
+compatibility for the now-upstream USB and GPU Devicetree schema. However, this will
+likely be our last m1n1 release that can be built without Rust.
+
+We believe that it is important for such a critical piece of software to be as
+maintainable, safe and logically sound as possible, especially given that it is
+*supposed* to root the chain of trust in a hypothetical Secure Boot environment.
+Certain components of m1n1 being written in C means that we currently cannot meet
+any of those goals.
+
+One such component was the Apple Device Tree handling code. While the ADT is
+implicitly trustworthy data, the original C implementation was quite haphazardly
+put together. This resulted in an unsound API based on libfdt that was neither
+ergonomic to use nor a particularly good fit for the ADT data itself.
+
+I was able to develop a sound, idiomatic Rust implementation and API with a little
+help from our resident Rust expert chaos_princess, and bind that back to the existing
+C API so that all our existing C code can make use of it. After a round of bug-squashing,
+we found that there is no speed difference between the old and new implementations,
+even with the overhead of the FFI glue logic!
+
+We don't have any plans to actively port *all* of m1n1 to Rust. Safety-critical
+components in the boot chain are our primary focus, followed closely by components
+which could directly benefit from a rewrite due to unsound or unergonomic C APIs.
+Perhaps one day we will have an all-Rust m1n1, but if it happens it will do so
+organically over time.
+
+## WoW!
+Last time, we teased working 64-bit Windows applications running in WINE outside of
+muvm. Granted, Notepad++ is not a particularly exciting teaser, but we believe it is
+important to be transparent and set realisitic expectations. Anyway, here are both
+Hollow Knight and NieR:Automata---64-bit Windows games---running on WINE outside of muvm.
+
+<figure>
+    <a href="/img/blog/2025/10/hollowknight.jpg">
+        <img src="/img/blog/2025/10/hollowknight.jpg" alt="Hollow Knight (2017) running outside of muvm on an M1 Pro MacBook Pro with Gentoo" />
+    </a>
+    <figcaption>
+        Hollow Knight (2017) running outside of muvm on an M1 Pro MacBook Pro with Gentoo
+    </figcaption>
+</figure>
+<br>
+
+<figure>
+    <a href="/img/blog/2025/10/nier.jpg">
+        <img src="/img/blog/2025/10/nier.jpg" alt="NieR:Automata (2017) running outside of muvm on an M1 Pro MacBook Pro with Gentoo" />
+    </a>
+    <figcaption>
+        NieR:Automata (2017) running outside of muvm on an M1 Pro MacBook Pro with Gentoo
+    </figcaption>
+</figure>
+
+Thanks once again to chaos_princess, the toolchain changes we were waiting for last
+time have now been integrated into Gentoo, and the required FEX DLLs are built
+automatically when installing WINE.
+
+Mileage will vary to an even greater degree than 32-bit applications, however.
+WINE's support for ARM64X and ARM64EC (Microsoft's ABI and executable format
+that allow AArch64 and amd64 code to interoperate) is still incomplete, so
+many applications simply will not work (yet). We of course encourage folks who
+like to live dangerously to give it a try, but we cannot provide any support
+for this stack. Consider it an early alpha, a glimpse at better things to come.
+
+## Helping developers
+When we first started the project, we created [macvdmtool](https://github.com/AsahiLinux/macvdmtool)
+to puppeteer a device under test using Apple's USB-PD Vendor Defined Messages.
+These allow the user to reboot a Mac over USB and to route the SoC's primary
+UART to the USB port. These features are very useful when doing early device
+bringup. Rebooting the machine with this method works even when the system is
+locked up, and having access to the UART means that we can inspect any boot logs
+without relying on an initialised display or USB stack. macvdmtool relies on IOKit,
+a macOS system library. Having to use macOS for development is painful, but what
+if we could achieve the same functionality with a Linux utility instead?
+
+[tuxvdmtool](https://github.com/AsahiLinux/tuxvdmtool) is a reimplementation
+of macvdmtool on Linux, made possible by changes to the USB-C mux chip driver
+present in our downstream kernel. tuxvdmtool offers the same features as macvdmtool,
+with the added benefit of allowing the "host" system to be an Apple Silicon device
+running Linux! Having access to a familiar and fully-featured Linux development
+environment helps make early bringup work just that little bit more accessible.
+We hope that tuxvdmtool encourages more folks to experiment with low-level bringup
+on Apple Silicon devices.
+
+While the kernel patches required to make this work are not upstreamable, a future
+release of tuxvdmtool will be rewritten to use the Linux kernel's builtin
+[i2c dev interface](https://docs.kernel.org/i2c/dev-interface.html), which will
+allow us to drop them entirely.
+
+## Helping everyone
+We have always strived to work directly with upstream projects on Apple Silicon
+support where possible. This allows us to discuss ideas with those projects, get
+advice on the correct way to implement Apple Silicon support in their software, and
+in many cases even benefit the ecosystem more broadly. While this means we are
+beholden to the relevant upstream's release schedule, it also means that we don't
+have to worry about maintaining outdated forks, rebasing, backporting security
+patches, and any of the other software engineering things that are not directly
+related to supporting Apple Silicon devices. The past year has demonstrated
+clearly why not just an an upstream-first, but upstream-*only* approach to
+development is the only approach that makes sense long term.
+
+But working upstream is not only for our own benefit. Sometimes, the work we
+do can be of benefit to other users on other platforms. Well documented examples
+of this include getting projects to [work properly](https://asahilinux.org/docs/sw/broken-software/#fixed-packages)
+on machines with 16K pages, and the PipeWire and WirePlumber enhancements that
+allow us to automatically apply DSP profiles to each device. These were done with
+the direct benefit to others front and centre of mind.
+
+Sometimes, however, it can be those other users who find our work and put it to
+use of their own accord.
+
+Geometry shaders are a type of specialised shader which can work directly on
+polygons rather than vertices. Although now considered a legacy technique,
+some applications use them for various tasks, such as culling triangles from
+a scene based on some sort of filter condition.
+
+Similarly, tessellation is a graphical technique that allows GPUs to programmatically
+fill a surface with new polygons. This is used to implement adaptive LOD, highly
+detailed water, and increase the fidelity of models without having to ship
+large, high-poly assets.
+
+Modern high-performance GPUs support both of these with additional hardware,
+however this requires engineering effort as well as room in the design's power
+and die area budgets. Mobile GPU designers aim to minimise all three of these
+and more often than not end up emulating both geometry shaders and tessellation.
+Apple's GPUs, being derived from PowerVR and originally designed for iDevices,
+are no exception.
+
+While Vulkan does not mandate support for geometry shaders for this reason, OpenGL
+does from version 3.2 onwards, as does Direct3D 10 and up. Since we would very
+much like to support OpenGL as well as Direct3D translation, we need to be
+able to execute geometry shaders somehow.
+
+We may not have explicit support for geometry shaders, we *do* have support for
+compute shaders. With these, we can emulate full geometry shader and tessellation
+support on the GPU itself and avoid a great deal of the performance penalty
+associated with using the CPU.
+
+Of course this isn't as performant as full hardware acceleration, but it does
+at least allow us to advertise support for geometry and tessellation shaders to
+applications. This in turn allows us to claim conformance with all modern OpenGL
+versions, allows Vulkan applications to use geometry and tessellation shaders,
+*and* enables the translation of Direct3D for games running under WINE/Proton!
+
+Other mobile GPUs also have this problem. Arm's GPU designs for example do not
+have hardware support for geometry shaders or tessellation either. 
+Enter [`poly`](https://gitlab.freedesktop.org/mesa/mesa/-/merge_requests/37914),
+an effort by Mary Guillemard to convert our geometry and tessellation shader emulation
+into shared code that any Mesa driver can use. This can then be integrated into
+any Mesa GPU driver, enabling geometry and tessellation shader support without
+duplicating the emulation code itself!
+
+Be sure to keep an eye out for geometry shader, tessellation shader, and transform
+feedback support in Panfrost, the open source Arm GPU driver, as well as in KosmicKrisp,
+a conformant Vulkan 1.3 implementation for macOS layered on top of Metal.
+
+## Life, the Universe, and Everything. Plus one.
+Keen eyes may have noticed we've started building Fedora Asahi Remix
+[dailies](https://fedora-asahi-remix.org/builds.html) targeting Fedora Linux 43.
+The new upstream Fedora release is slated to come out later this month, and
+you can expect the Remix to follow shortly.
+
+## At the Akademy
+Neal and Janne attended [KDE Akademy](https://akademy.kde.org/) in Berlin this year.
+As the annual KDE community conference, this was an opportunity to ensure future work
+in KDE aligns well with Fedora Linux and Fedora Asahi Remix. Neal
+[gave a talk](https://youtu.be/CznIsJQQE9U?t=248) about the Fedora KDE Plasma Desktop
+Edition there, and prominently discussed Fedora Asahi Remix as part of it.
+
+Additionally, there was a lot of discussion about the upcoming Plasma Setup application,
+which will provide a better integrated experience for first boot of a Fedora KDE
+install. Lessons learnt from Fedora Asahi Remix user feedback is being directly
+incorporated into Plasma Setup, and Neal is working on integrating this for Fedora
+Linux 44 as [a formal Change](https://fedoraproject.org/wiki/Changes/Unified_KDE_OOBE).
+
+## M3? Kinda...
+Way back in the early days, we predicted that Apple would refrain from making
+sweeping architectural changes to the various functional blocks found in Apple Silicon
+SoCs unless absolutely necessary, and that this would enable the reuse of a
+lot of code and significantly cut down on the amount of reverse engineering required
+between generations. The example we gave was the interrupt controller, which is
+quite unfortunate because that was the first thing Apple ended up changing. Oops.
+
+But the overall principle has held mostly true. So much so in fact that some
+enterprising folks on Reddit have found that with only a trivial amount of
+hacking, you can actually boot Asahi on M3 series devices!
+
+It may be surprising to learn that very basic, low-level support for M3 has
+existed for quite some time now. m1n1 is capable of initialising the CPU cores,
+turning on some critical peripheral devices, and booting the Asahi kernel.
+However, the level of support right now begins and ends with being able to boot
+to a blinking cursor. Naturally, this level of support is not at all useful for
+anything but low-level reverse engineering, but we of course plan on rectifying
+this in due time...
+
+If you're interested in helping us out and have prior experience with reverse
+engineering or low-level embedded software development, we'd love for you to say
+hi on IRC or Matrix! See [this page](https://asahilinux.org/contribute) for more
+information.
+
+## Thanks!
+As always, a warm thanks to our sponsors on [OpenCollective](https://opencollective.com/asahilinux)
+and [GitHub Sponsors](https://github.com/sponsors/asahilinux), without whom we
+would not be able to keep the lights on. You're all truly wonderful!