From: Michael Ellerman <mpe@ellerman.id.au>
To: Christoph Hellwig <hch@lst.de>, torvalds@linux-foundation.org
Cc: kvm@vger.kernel.org, pbonzini@redhat.com, linux-kernel@vger.kernel.org
Subject: Re: [PATCH] Revert "KVM: x86: enable -Werror"
Date: Thu, 27 Feb 2020 14:33:30 +1100 [thread overview]
Message-ID: <87v9ns1z79.fsf@mpe.ellerman.id.au> (raw)
In-Reply-To: <20200226153929.786743-1-hch@lst.de>
Christoph Hellwig <hch@lst.de> writes:
> This reverts commit ead68df94d248c80fdbae220ae5425eb5af2e753.
>
> Using the brain dead Werror flag fixes the build for me due to mostly
> harmless KASAN or similar warnings:
>
> arch/x86/kvm/x86.c: In function ‘kvm_timer_init’:
> arch/x86/kvm/x86.c:7209:1: error: the frame size of 1112 bytes is larger than 1024 bytes [-Werror=frame-larger-than=]
> 7209 | }
>
> Feel free to add a CONFIG_WERROR if you care strong enough, but don't break
> peoples builds for absolutely no good reason.
>
> Signed-off-by: Christoph Hellwig <hch@lst.de>
> ---
> arch/x86/kvm/Makefile | 1 -
> 1 file changed, 1 deletion(-)
>
> diff --git a/arch/x86/kvm/Makefile b/arch/x86/kvm/Makefile
> index 4654e97a05cc..b19ef421084d 100644
> --- a/arch/x86/kvm/Makefile
> +++ b/arch/x86/kvm/Makefile
> @@ -1,7 +1,6 @@
> # SPDX-License-Identifier: GPL-2.0
>
> ccflags-y += -Iarch/x86/kvm
> -ccflags-y += -Werror
>
> KVM := ../../../virt/kvm
We've had -Werror enabled by default on powerpc for over 10 years, and
haven't had many complaints. Possibly that's just because no one builds
powerpc kernels ...
The key thing is that it's configurable, so if it does break the build
for someone they can just turn it off. It's also off by default for
allyes/allmod builds because the user-selectable option disables
-Werror, eg:
config PPC_DISABLE_WERROR
bool "Don't build arch/powerpc code with -Werror"
help
This option tells the compiler NOT to build the code under
arch/powerpc with the -Werror flag (which means warnings
are treated as errors).
Only enable this if you are hitting a build failure in the
arch/powerpc code caused by a warning, and you don't feel
inclined to fix it.
config PPC_WERROR
bool
depends on !PPC_DISABLE_WERROR
default y
In fact these days with shell support in Kconfig we could make it even
smarter, eg:
diff --git a/arch/powerpc/Kconfig.debug b/arch/powerpc/Kconfig.debug
index 0b063830eea8..e7564f7cabc6 100644
--- a/arch/powerpc/Kconfig.debug
+++ b/arch/powerpc/Kconfig.debug
@@ -2,6 +2,7 @@
config PPC_DISABLE_WERROR
bool "Don't build arch/powerpc code with -Werror"
+ default $(success,whoami | grep hch)
help
This option tells the compiler NOT to build the code under
arch/powerpc with the -Werror flag (which means warnings
cheers
next prev parent reply other threads:[~2020-02-27 3:33 UTC|newest]
Thread overview: 3+ messages / expand[flat|nested] mbox.gz Atom feed top
2020-02-26 15:39 [PATCH] Revert "KVM: x86: enable -Werror" Christoph Hellwig
2020-02-27 3:33 ` Michael Ellerman [this message]
2020-02-27 6:41 ` Paolo Bonzini
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