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 :)

    • Bluetooth: Fix type of len in {l2cap,sco}_sock_getsockopt_old() (v1)
    • powerpc: Fix fatal warnings flag for LLVM's integrated assembler (v1)
    • drm/xe: Add xe_guc_ads.c to uses_generated_oob (v1)
  • Downstream fixes: These are fixes and improvements that occur in a downstream Linux tree, such as Android or ChromeOS, which our continuous integration regularly tests.

  • Miscellaneous fixes and improvements: These are fixes and improvements that don’t fit into a particular category but are important to ClangBuiltLinux.

    • configs/hardening: Some fixes for UBSAN (v1)
    • selftests: Make ksft_exit functions return void instead of int (v1, v2)
    • x86/purgatory: Avoid kexec runtime warning with LLVM 18 (v1)
    • clk: bcm: Move a couple of __counted_by initializations (v1)
  • Warning fixes: These are patches to fix various warnings that appear with LLVM. I used to go into detail about the different warnings and what they mean, but the important takeaway for this section is that the kernel should build warning free, as all developers should be using CONFIG_WERROR, which will turn these all into failures. Maybe these should be in the build failures section…

    • MIPS: Add prototypes for plat_post_relocation() and relocate_kernel() (v1)
    • kselftest: Mark functions that unconditionally call exit() as __noreturn (v1)
    • bcachefs: Fix format specifier in validate_bset_keys() (v1)
    • drivers/s390: Fix instances of -Wcast-function-type-strict (v1)
    • ALSA: scarlett2: Zero initialize ret in scarlett2_ag_target_ctl_get() (v1)
    • bcachefs: Fix type of flags parameter for some ->trigger() implementations (v1)
    • bcachefs: Fix format specifiers in bch2_btree_key_cache_to_text() (v1)
    • drm/amd/display: Avoid -Wenum-float-conversion in add_margin_and_round_to_dfs_grainularity() (v1)
    • drm/amd/display: Use frame_warn_flag consistently in dml2 Makefile (v1)

LLVM patches

Patch review and input

For the next sections, I link directly to my first response in the thread when possible but there are times where the link is to the main post. My responses can be seen inline by going to the bottom of the thread and clicking on my name.

Reviewing patches that are submitted is incredibly important, as it helps ensure good code quality due to catching mistakes before the patches get accepted and it can help get patches accepted faster, as some maintainers will blindly pick up patches that have been reviewed by someone that they trust.

Issue triage, input, and reporting

The unfortunate thing about working at the intersection of two projects is we will often find bugs that are not strictly related to the project, which require some triage and reporting back to the original author of the breakage so that they can be fixed and not impact our own testing. Some of these bugs fall into that category while others are issues strictly related to this project.

Tooling improvements

These are changes to various tools that we use, such as our continuous integration setup, booting utilities, toolchain building scripts, or other closely related projects such as AOSP’s distribution of LLVM and TuxMake.

Behind the scenes

  • Every day that there is a new linux-next release, I rebase and build a few different kernel trees then boot and runtime test them on several different machines, including a Raspberry Pi 4, a Raspberry Pi 3, a SolidRun Honeycomb LX2, an Ampere Altra Developer Platform, an Intel-based desktop, an AMD-based desktop, and an Intel-based laptop. This is not always visible because I do not report anything unless there is something broken but it can take up to a few hours each day, depending on the amount of churn and issues uncovered.

  • I ran the April 3rd and April 17th ClangBuiltLinux meetings.

  • I continue to upload prebuilt, fast versions of LLVM for kernel developers and our continuous integration to use.

Special thanks

Special thanks to Google and the Linux Foundation for sponsoring my work.