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 :)

    • clk: qcom: gpucc-sm8350: Fix "initializer element is not constant" error (v1, v2)
    • bpf, arm64: Mark dummy_tramp as global (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…

    • x86/speculation: Use DECLARE_PER_CPU for x86_spec_ctrl_current (v1, v2)
    • ASoC: Intel: avs: Mark avs_path_module_type_create() as noinline (v1)
    • btrfs: Fix unused variable in load_free_space_cache() (v1)
    • ASoC: amd: acp: Fix initialization of ext_intr_stat1 in i2s_irq_handler() (v1)
    • ion: Make user_ion_handle_put_nolock() a void function (v1)

  • Other fixes: These are fixes that don’t fit into a particular category but are important to ClangBuiltLinux. In this particular case, there was a Control Flow Integrity (CFI) violation in the simpledrm driver, which can cause kernels compiled with CFI to panic when booting.

    • drm/simpledrm: Fix return type of simpledrm_simple_display_pipe_mode_valid() (v1)

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 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 Windows Subsystem for Linux instance, a Raspberry Pi 3 and 4, 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.

Special thanks to: