Re: [PATCH v4 0/4] tools/build: Allow versioning of all LLVM tools

Hello BPF folks,

On Wed, Jul 15, 2026 at 03:53:47PM +0100, James Clark wrote:
> I ran into the build issue mentioned in the first commit, because using
> an option like LLVM=-15 is a documented way to build [1], but only
> some of the LLVM tools defined in tools/ support this.
> 
> After fixing that, a lot of other tidyups fell out. I didn't go too far,
> for example some selftests include tools/testing/selftests/lib.mk which
> reimplements some of the LLVM_SUFFIX stuff, but other selftests include
> tools/scripts/Makefile.include and I stopped before touching the former.
> Some other non build scripts hard code toolchains and I didn't touch
> those either, this change is only focused on things that already
> include Makefile.include.
> 
> [1]: Documentation/kbuild/llvm.rst
> 
> Signed-off-by: James Clark <[email protected]>
> ---
> Changes in v4:
> - Drop "tools/build: selftests: Allow versioning LLVM lld", clang
>   already picks the correct sibling lld version. (Sashiko)
> - Link to v3: https://lore.kernel.org/r/[email protected]
> 
> Changes in v3:
> - Add warning for empty $USE_LD
> - Use $HOSTREADELF in bpf Makefile
> - Rebase on v7.2-rc3
> - Link to v2: https://lore.kernel.org/r/[email protected]
> 
> Changes in v2:
> - Fix selftests/bpf build. LLD needs to take the full path to be used
>   with -fuse-ld=
> - Link to v1: https://lore.kernel.org/r/[email protected]
> 
> ---
> James Clark (4):
>       tools/build: Allow versioning of all LLVM tools defined in Makefile.include
>       tools/build: Indent if else blocks
>       tools/build: Allow versioning LLVM readelf
>       tools/build: selftests: Remove some duplicate toolchain definitions
> 
>  tools/bpf/resolve_btfids/Makefile    |  3 --
>  tools/lib/api/Makefile               |  4 --
>  tools/lib/bpf/Makefile               |  8 ++--
>  tools/lib/subcmd/Makefile            |  4 --
>  tools/lib/symbol/Makefile            |  4 --
>  tools/perf/Makefile.perf             |  7 ----
>  tools/scripts/Makefile.include       | 77 ++++++++++++++++++++----------------
>  tools/testing/selftests/bpf/Makefile |  1 -
>  8 files changed, 46 insertions(+), 62 deletions(-)

Are you ok with this change and going through perf tree?

Thanks,
Namhyung

> ---
> base-commit: a13c140cc289c0b7b3770bce5b3ad42ab35074aa
> change-id: 20260511-james-perf-llvm-version-43ab1cb5bc7d
> 
> Best regards,
> -- 
> James Clark <[email protected]>
>