From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from smtp.kernel.org (aws-us-west-2-korg-mail-1.web.codeaurora.org [10.30.226.201]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by smtp.subspace.kernel.org (Postfix) with ESMTPS id 12BD32F21 for ; Tue, 8 Feb 2022 16:04:20 +0000 (UTC) Received: by smtp.kernel.org (Postfix) with ESMTPSA id 3931FC004E1; Tue, 8 Feb 2022 16:04:19 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=k20201202; t=1644336260; bh=fkcM/cj5TPbLIL53k1xCwKgNr/uerJzMAH9JtGLwnIY=; h=Date:From:To:Cc:Subject:References:In-Reply-To:From; b=W2ObtUKMEXvRy3dBC56Fc90mt+dAL+rivWu2owCuXVq8ZkTywujYcg7GOXvqjaWWp k1pRIEVq8nEywWeHrVSZZCzZ9wVomBrnw5TiJO8JAPHGaQs0/XpWJ+ZhMQgghtnEBQ zt5+pTF0G8ydZtXrTlgEAMNpnskaa3TOQRqYoTqbb82TLr88AyZNd0B5+TlKhp+HFu 284mtD2ZKWuxgUlOrQUub9s0VTX9HFVkNtvDeFVONHQTtrxa5k4W0g3Ts8j+0fwE0O PEYwLJnJvqSXkdHI2rljnF9jkSuDrQr8mz9byg6MSbhL6JBxS1RdPOBWzerws73Ax6 NPl8wJWcYhfVQ== Date: Tue, 8 Feb 2022 09:04:16 -0700 From: Nathan Chancellor To: Masahiro Yamada Cc: Nick Desaulniers , Arnd Bergmann , Linux Kbuild mailing list , Linux Kernel Mailing List , llvm@lists.linux.dev, stable Subject: Re: [PATCH v2] Makefile.extrawarn: Move -Wunaligned-access to W=1 Message-ID: References: <20220202230515.2931333-1-nathan@kernel.org> Precedence: bulk X-Mailing-List: llvm@lists.linux.dev List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: On Tue, Feb 08, 2022 at 01:23:32PM +0900, Masahiro Yamada wrote: > On Thu, Feb 3, 2022 at 8:12 AM Nick Desaulniers wrote: > > > > On Wed, Feb 2, 2022 at 3:07 PM Nathan Chancellor wrote: > > > > > > -Wunaligned-access is a new warning in clang that is default enabled for > > > arm and arm64 under certain circumstances within the clang frontend (see > > > LLVM commit below). On v5.17-rc2, an ARCH=arm allmodconfig build shows > > > 1284 total/70 unique instances of this warning (most of the instances > > > are in header files), which is quite noisy. > > > > > > To keep a normal build green through CONFIG_WERROR, only show this > > > warning with W=1, which will allow automated build systems to catch new > > > instances of the warning so that the total number can be driven down to > > > zero eventually since catching unaligned accesses at compile time would > > > be generally useful. > > > > > > Cc: stable@vger.kernel.org > > > Link: https://github.com/llvm/llvm-project/commit/35737df4dcd28534bd3090157c224c19b501278a > > > Link: https://github.com/ClangBuiltLinux/linux/issues/1569 > > > Link: https://github.com/ClangBuiltLinux/linux/issues/1576 > > > Signed-off-by: Nathan Chancellor > > > > Thanks to you and Arnd for working out whether this is important to > > pursue. Sounds like it is. > > Reviewed-by: Nick Desaulniers > > > > > --- > > > I assume this should be considered as a bug fix > to avoid the error for the combination of CONFIG_WERROR=y > and the latest Clang. > > Applied to linux-kbuild/fixes. > Thanks. Yes, this is what I was hoping for! Thank you, I'll try to make that more clear in the future. Cheers, Nathan > > > > > > v1 -> v2: https://lore.kernel.org/r/20220201232229.2992968-1-nathan@kernel.org/ > > > > > > * Move to W=1 instead of W=2 so that new instances are caught (Arnd). > > > * Add links to the ClangBuiltLinux issue tracker. > > > > > > scripts/Makefile.extrawarn | 1 + > > > 1 file changed, 1 insertion(+) > > > > > > diff --git a/scripts/Makefile.extrawarn b/scripts/Makefile.extrawarn > > > index d53825503874..8be892887d71 100644 > > > --- a/scripts/Makefile.extrawarn > > > +++ b/scripts/Makefile.extrawarn > > > @@ -51,6 +51,7 @@ KBUILD_CFLAGS += -Wno-sign-compare > > > KBUILD_CFLAGS += -Wno-format-zero-length > > > KBUILD_CFLAGS += $(call cc-disable-warning, pointer-to-enum-cast) > > > KBUILD_CFLAGS += -Wno-tautological-constant-out-of-range-compare > > > +KBUILD_CFLAGS += $(call cc-disable-warning, unaligned-access) > > > endif > > > > > > endif > > > > > > base-commit: 26291c54e111ff6ba87a164d85d4a4e134b7315c > > > -- > > > 2.35.1 > > > > > > > > > -- > > Thanks, > > ~Nick Desaulniers > > > > -- > Best Regards > Masahiro Yamada