On Wed, Dec 29, 2021 at 01:55:34PM -0800, Nick Desaulniers wrote:

Dear Stable Kernel Maintainers, Please consider applying the attached mbox file to v5.10.y.

For Android's T release in 2022, I'd like to verify whether clang's integrated assembler was used. For the compiler and linker, they both embed a string in object file that can be read via:

$ llvm-readelf -p .comment <object file> String dump of section '.comment': [ 0] Linker: LLD 14.0.0 [ 13] clang version 14.0.0 (git@github.com:llvm/llvm-project.git 2ff26d0e794ab7300d94051f91be7da274cc348e)

Unfortunately, the assembler version is not also embedded. Instead, I'd like to check for the presence of AS_IS_LLVM in .config. This series helps move some toolchain version checking from build time to configure time, though that's only a modest improvement and I don't _have_ to check this config.

The mbox contains the following 7 commits:

1. commit 052c805a1851 ("kbuild: LD_VERSION redenomination")
2. commit aec6c60a01d3 ("kbuild: check the minimum compiler version in Kconfig")
3. commit 02aff8592204 ("kbuild: check the minimum linker version in Kconfig")
4. commit 1f09af062556 ("kbuild: Fix ld-version.sh script if LLD was

built with LLD_VENDOR") 5. commit bcbcf50f5218 ("kbuild: fix ld-version.sh to not be affected by locale") 6. commit e24b3ffcf421 ("kbuild: collect minimum tool versions into scripts/min-tool-version.sh") 7. commit ba64beb17493 ("kbuild: check the minimum assembler version in Kconfig")

They landed respectively upstream in:

1. v5.12-rc1
2. v5.12-rc1
3. v5.12-rc1
4. v5.12-rc3
5. v5.12-rc3
6. v5.13-rc1
7. v5.13-rc1

I needed to manually resolve conflicts in the respective patches:

1. N/A
2. N/A
3. scripts/lld-version.sh due to df58fb431aa3

("scripts/lld-version.sh: Rewrite based on upstream ld-version.sh") being 5.10 only. This file is removed regardless of what it looks like. 4. N/A 5. N/A 6. N/A 7. arch/Kconfig due to missing dc5723b02e523 ("kbuild: add support for Clang LTO") which landed in v5.12-rc1.

While I can appreciate your quest to make your Android kernel trees smaller, this really looks like a "new feature". What bug/issue is this fixing that is currently present in 5.10 that people are hitting today?

thanks,

greg k-h