Posts

Occasionally, I will forget to link something from the mailing list in this post. To see my full mailing list activity (patches, reviews, and reports), you can view it on lore.kernel.org. Linux kernel patches Miscellaneous fixes and improvements: These are fixes and improvements that don’t fit into a particular category but are important to ClangBuiltLinux. scripts/Makefile.extrawarn: Do not disable clang's -Wformat-zero-length (v1) x86/build: Move '-mindirect-branch-cs-prefix' out of GCC-only block (v1) Stable backport requests: It is important to make sure that the stable trees are as free from issues as possible, as those are the trees that devices and users use; for example, Android and Chrome OS regularly merge from stable, so if there is a problem that will impact those trees that we fixed in mainline, it should be backported. ...

Occasionally, I will forget to link something from the mailing list in this post. To see my full mailing list activity (patches, reviews, and reports), you can view it on lore.kernel.org. Linux kernel patches Build errors: These are patches to fix various build errors that I found through testing different configurations with LLVM or were exposed by our continuous integration setup. The kernel needs to build in order to be run :) ...

Occasionally, I will forget to link something from the mailing list in this post. To see my full mailing list activity (patches, reviews, and reports), you can view it on lore.kernel.org. Linux kernel patches Android changes: Android is one of the largest downstream consumers of our work. Our continuous integeration tests the Android trees with newer versions of LLVM to help catch any issues that will impact Android once they upgrade their version of LLVM, which can lag behind at times. ...

Occasionally, I will forget to link something from the mailing list in this post. To see my full mailing list activity (patches, reviews, and reports), you can view it on lore.kernel.org. Linux kernel patches Build errors: These are patches to fix various build errors that I found through testing different configurations with LLVM or were exposed by our continuous integration setup. The kernel needs to build in order to be run :) ...

Recently, I started exploring setting up a self-hosted GitHub Actions runner for the work-in-progress LLVM builds that ClangBuiltLinux is looking to distribute on kernel.org, as GitHub Actions hosted runners are pretty underwhelming in terms of performance and we want to soup these builds up with Profile Guided Optimization. Additionallly, GitHub Actions does not have a hosted arm64 Linux option, which is becoming increasingly important with chips such as Apple’s M1 getting strong mainline Linux support. ...

Occasionally, I will forget to link something from the mailing list in this post. To see my full mailing list activity (patches, reviews, and reports), you can view it on lore.kernel.org. Linux kernel patches Build failures: These are patches to fix various build errors that I found through testing different configurations with LLVM or were exposed by our continuous integration setup. The kernel needs to build in order to be run :) ...

Occasionally, compiling the Linux kernel with a new compiler flag will result in a boot failure. If you are lucky, there will be some output to the serial console but that may not happen if the issue happens in early boot code before the serial driver has loaded. When this happens, it usually requires building part of the kernel without the compiler flag (or the “negative” version of it) to try and figure out the exact translation unit and function that causes the problem. I’ll go over this process at a high level to help others who might encounter this same issue. ...

As a Linux kernel developer, I will often need to build and boot new kernels to hunt down issues or test new functionality for regressions. While it is possible to manually install these kernels on machines, it is easiest to use the distribution’s package manager, as the kernel does not need to be built on the machine it is being installed on. With .deb and .rpm-based systems, it is easy to build a kernel package within the kernel source itself, using the bindeb-pkg and binrpm-pkg targets respectively. However, for Arch Linux, my distribution of choice, that is not so simple. Furthermore, when doing certain types of development, such as bisecting an issue, it is more convenient to do all the building in an actual source tree, rather than one that is managed by the Arch Build System. The following process might not be the most efficient or optimal way to do this process (the Arch wiki has a whole article about doing a git bisect with a PKGBUILD) but it works for me :) ...

Occasionally, I will forget to link something from the mailing list in this post. To see my full mailing list activity (patches, reviews, and reports), you can view it on lore.kernel.org. Linux kernel patches Boot fixes: These patches fix boot failures that we have seen in testing. In this case, it is a User Mode Linux fix, which we are looking to enable in our continuous integration setup, as it is useful for quick testing. ...

Occasionally, I will forget to link something from the mailing list in this post. To see my full mailing list activity (patches, reviews, and reports), you can view it on lore.kernel.org. Linux kernel patches Miscellaneous improvements: These are series or patches that do not really fit into any of the other categories I typically use with my reports. Allow CONFIG_DEBUG_INFO_DWARF5=y + CONFIG_DEBUG_INFO_BTF=y (v1) tools/resolve_btfids: Do not print any commands when building silently (v1) -Wenum-conversion: This warning occurs when one enumerated type is implicitly converted to another enumerated type, which is typically a bug, although it might not actually be a problem in practice if the used enum has the same value as the intended enum (which is the case here). It is still good to get it corrected, as the enums might not stay in sync. ...