Re: [PATCH 0/2] Remove '-mno-global-merge' from KBUILD_CFLAGS

Masahiro Yamada
2022-04-01T13:05:07Z

On Thu, Mar 31, 2022 at 8:46 AM Nathan Chancellor <nathan@kernel.org> wrote:
>
> As discussed at [1] and [2], this series removes '-mno-global-merge'
> from KBUILD_CFLAGS for clang, as it causes warnings for UML, and it
> no longer appears to be necessary, as I do not see any modpost warnings
> with LLVM 11 through 15 with several different ARCH=arm and ARCH=arm64
> configurations.
>
> [1] is currently in the UML tree, destined for 5.18, but it is buggy, as
> I note in [2]. This series is an alternative to [2], which has not been
> picked up yet, so it is based on the current UML tree. If [2] is picked
> up, I can rework the first patch to remove the '-mno-global-merge'
> filtering from arch/um/Makefile; otherwise, this should be picked up in
> place of [2].
>
> I intentionally kept the first patch vague around what fixed the modpost
> warnings, as I am not too sure. [3] seems somewhat likely, but I don't
> think that will revert cleanly on main to test. I think the testing is
> enough to show that the original issue is resolved but I do note that we
> can add this flag back in the architecture specific Makefiles if needed.
>
> Please review and ack as necessary.

Both applied to linux-kbuild/fixes.

> [1]: https://lore.kernel.org/r/20220303090643.241747-1-davidgow@google.com/
> [2]: https://lore.kernel.org/r/20220322173547.677760-1-nathan@kernel.org/
> [3]: https://github.com/llvm/llvm-project/commit/863bfdbfb446adaef767ff514d1f2ffb5d489562
>
> Nathan Chancellor (2):
> kbuild: Remove '-mno-global-merge'
> Revert "um: clang: Strip out -mno-global-merge from USER_CFLAGS"
>
> Makefile | 4 ----
> arch/um/Makefile | 4 ----
> 2 files changed, 8 deletions(-)
>
>
> base-commit: 82017457957a550d7d00dde419435dd74a890887
> --
> 2.35.1
>

--
Best Regards
Masahiro Yamada