linux-kernel - Re: [PATCH v2 01/10] kbuild: don't enable CC_CAN_LINK if the dummy program generates warnings

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Message-ID: <20251114143845-ff0d3849-4495-469c-b9c1-bebf2e8808db@linutronix.de>
Date: Fri, 14 Nov 2025 14:43:24 +0100
From: Thomas Weißschuh <thomas.weissschuh@...utronix.de>
To: Nathan Chancellor <nathan@...nel.org>
Cc: Nicolas Schier <nicolas.schier@...ux.dev>, 
	Nicolas Schier <nsc@...nel.org>, Paul Walmsley <pjw@...nel.org>, 
	Palmer Dabbelt <palmer@...belt.com>, Albert Ou <aou@...s.berkeley.edu>, 
	Alexandre Ghiti <alex@...ti.fr>, Heiko Carstens <hca@...ux.ibm.com>, 
	Vasily Gorbik <gor@...ux.ibm.com>, Alexander Gordeev <agordeev@...ux.ibm.com>, 
	Christian Borntraeger <borntraeger@...ux.ibm.com>, Sven Schnelle <svens@...ux.ibm.com>, 
	Madhavan Srinivasan <maddy@...ux.ibm.com>, Michael Ellerman <mpe@...erman.id.au>, 
	Nicholas Piggin <npiggin@...il.com>, Christophe Leroy <christophe.leroy@...roup.eu>, 
	Thomas Bogendoerfer <tsbogend@...ha.franken.de>, Thomas Gleixner <tglx@...utronix.de>, 
	Ingo Molnar <mingo@...hat.com>, Borislav Petkov <bp@...en8.de>, 
	Dave Hansen <dave.hansen@...ux.intel.com>, x86@...nel.org, "H. Peter Anvin" <hpa@...or.com>, 
	"David S. Miller" <davem@...emloft.net>, Andreas Larsson <andreas@...sler.com>, 
	linux-kbuild@...r.kernel.org, linux-kernel@...r.kernel.org, 
	Masahiro Yamada <masahiroy@...nel.org>, linux-riscv@...ts.infradead.org, linux-s390@...r.kernel.org, 
	linuxppc-dev@...ts.ozlabs.org, linux-mips@...r.kernel.org, sparclinux@...r.kernel.org
Subject: Re: [PATCH v2 01/10] kbuild: don't enable CC_CAN_LINK if the dummy
 program generates warnings

On Thu, Nov 13, 2025 at 09:27:41PM -0700, Nathan Chancellor wrote:
> On Tue, Oct 14, 2025 at 03:05:16PM +0200, Thomas Weißschuh wrote:
> > It is possible that the kernel toolchain generates warnings when used
> > together with the system toolchain. This happens for example when the
> > older kernel toolchain does not handle new versions of sframe debug
> > information. While these warnings where ignored during the evaluation
> > of CC_CAN_LINK, together with CONFIG_WERROR the actual userprog build
> > will later fail.
> > 
> > Example warning:
> > 
> > .../x86_64-linux/13.2.0/../../../../x86_64-linux/bin/ld:
> > error in /lib/../lib64/crt1.o(.sframe); no .sframe will be created
> > collect2: error: ld returned 1 exit status
> > 
> > Make sure that the very simple example program does not generate
> > warnings already to avoid breaking the userprog compilations.
> > 
> > Fixes: ec4a3992bc0b ("kbuild: respect CONFIG_WERROR for linker and assembler")
> > Fixes: 3f0ff4cc6ffb ("kbuild: respect CONFIG_WERROR for userprogs")
> > Signed-off-by: Thomas Weißschuh <thomas.weissschuh@...utronix.de>
> 
> Reviewed-by: Nathan Chancellor <nathan@...nel.org>

Thanks!

> While this makes sense as a way to immediately fix the problem and align
> cc-can-link.sh with the other test functions like cc-option and like, it
> is rather unfortunate that this particular warning causes an error since
> the rest of the userprogs infrastructure does not care about SFrame...
> I wonder if there is a way to avoid it since I think this warning does
> not point to a fundamental problem.

I did not find any way to avoid this specific warning, unfortunately.
This patch should make sense in any case. If we find a way to avoid the
sframe warning then that should go on top.

(...)


Thomas