From: Borislav Petkov <bp@alien8.de>
To: Nathan Chancellor <nathan@kernel.org>
Cc: Thomas Gleixner <tglx@linutronix.de>,
Ingo Molnar <mingo@redhat.com>,
x86@kernel.org, Masahiro Yamada <masahiroy@kernel.org>,
"H. Peter Anvin" <hpa@zytor.com>,
Nick Desaulniers <ndesaulniers@google.com>,
linux-kernel@vger.kernel.org, linux-kbuild@vger.kernel.org,
clang-built-linux@googlegroups.com, llvm@lists.linux.dev,
kernel test robot <lkp@intel.com>
Subject: Re: [PATCH 1/2] x86: Do not add -falign flags unconditionally for clang
Date: Thu, 16 Sep 2021 19:18:42 +0200 [thread overview]
Message-ID: <YUN8coiEx3JZQytc@zn.tnic> (raw)
In-Reply-To: <20210824022640.2170859-2-nathan@kernel.org>
On Mon, Aug 23, 2021 at 07:26:39PM -0700, Nathan Chancellor wrote:
A couple of nitpicks:
> Subject: [PATCH 1/2] x86: Do not add -falign flags unconditionally for clang
Make that prefix into "x86/build: "
> clang does not support -falign-jumps and only recently gained support
> for -falign-loops. When one of the configuration options that adds these
> flags is enabled, clang warns and all cc-{disable-warning,option} that
> follow fail because -Werror gets added to test for the presence of this
> warning:
>
> clang-14: warning: optimization flag '-falign-jumps=0' is not supported
> [-Wignored-optimization-argument]
>
> To resolve this, add a couple of cc-option calls when building with
> clang; gcc has supported these options since 3.2 so there is no point in
> testing for their support. -falign-functions was implemented in clang-7,
> -falign-loops was implemented in clang-14, and -falign-jumps has not
> been implemented yet.
>
> Link: https://lore.kernel.org/r/YSQE2f5teuvKLkON@Ryzen-9-3900X.localdomain/
Also, there should be a second Link: tag which points to this mail
thread so that we can find it later, when we dig for the "why we did
that" question :)
I.e.,
Link: 20210824022640.2170859-2-nathan@kernel.org
> Reported-by: kernel test robot <lkp@intel.com>
> Signed-off-by: Nathan Chancellor <nathan@kernel.org>
> ---
> arch/x86/Makefile_32.cpu | 12 +++++++++---
> 1 file changed, 9 insertions(+), 3 deletions(-)
with that:
Acked-by: Borislav Petkov <bp@suse.de>
Thx.
--
Regards/Gruss,
Boris.
https://people.kernel.org/tglx/notes-about-netiquette
next prev parent reply other threads:[~2021-09-16 17:18 UTC|newest]
Thread overview: 11+ messages / expand[flat|nested] mbox.gz Atom feed top
2021-08-24 2:26 [PATCH 0/2] Harden clang against unknown flag options Nathan Chancellor
2021-08-24 2:26 ` [PATCH 1/2] x86: Do not add -falign flags unconditionally for clang Nathan Chancellor
2021-08-24 2:56 ` Fangrui Song
2021-08-24 21:53 ` Nathan Chancellor
2021-08-25 22:32 ` Nick Desaulniers
2021-09-16 17:18 ` Borislav Petkov [this message]
2021-09-16 18:42 ` Nathan Chancellor
2021-09-16 19:05 ` Borislav Petkov
2021-08-24 2:26 ` [PATCH 2/2] kbuild: Add -Werror=ignored-optimization-argument to CLANG_FLAGS Nathan Chancellor
2021-08-25 22:27 ` Nick Desaulniers
2021-09-13 18:08 ` [PATCH 0/2] Harden clang against unknown flag options Nathan Chancellor
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