linux-kernel - Re: [RFC] Don't create sframes during build

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Message-ID: <20260129222357.GA493990@ax162>
Date: Thu, 29 Jan 2026 15:23:57 -0700
From: Nathan Chancellor <nathan@...nel.org>
To: Jens Remus <jremus@...ux.ibm.com>
Cc: Matthias Klose <doko@...ian.org>,
	Sebastian Andrzej Siewior <bigeasy@...utronix.de>,
	linux-arch@...r.kernel.org, linux-kernel@...r.kernel.org,
	linux-kbuild@...r.kernel.org, Arnd Bergmann <arnd@...db.de>,
	Josh Poimboeuf <jpoimboe@...nel.org>,
	Peter Zijlstra <peterz@...radead.org>,
	Nicolas Schier <nicolas.schier@...ux.dev>,
	Binutils <binutils@...rceware.org>,
	Heiko Carstens <hca@...ux.ibm.com>,
	Vasily Gorbik <gor@...ux.ibm.com>,
	Indu Bhagat <indu.bhagat@...cle.com>
Subject: Re: [RFC] Don't create sframes during build

On Thu, Jan 29, 2026 at 10:13:03AM +0100, Jens Remus wrote:
> Instead of dropping .sframe for kernel during final link it would be
> better not to generate it to save some CPU cycles and disk space.
...
> What about:
> 
> diff --git a/Makefile b/Makefile
> --- a/Makefile
> +++ b/Makefile
> @@ -906,6 +906,11 @@ KBUILD_CFLAGS	+= $(call cc-option,--param=allow-store-data-races=0)
>  KBUILD_CFLAGS	+= $(call cc-option,-fno-allow-store-data-races)
>  endif
> 
> +# No .sframe generation for kernel if enabled in assembler by default
> +CC_FLAGS_SFRAME	:= $(call as-option,-Wa$(comma)--gsframe=no)
> +KBUILD_CFLAGS	+= $(CC_FLAGS_SFRAME)
> +KBUILD_AFLAGS	+= $(CC_FLAGS_SFRAME)
> +
>  ifdef CONFIG_READABLE_ASM
>  # Disable optimizations that make assembler listings hard to read.
>  # reorder blocks reorders the control in the function

This seems like a good start for the main kernel build. I still have an
issue with bleeding edge binutils with mismatched .sframe input
sections, which does not appear to disappear with -Wa,--gsframe=no.

  $ cat test.c
  void atexit();
  void main() { atexit(); }

  $ gcc --version | head -1
  gcc (GCC) 15.2.1 20260103

  $ ld --version | head -1
  GNU ld (GNU Binutils) 2.45.50.20260128

  $ gcc -o /dev/null test.c
  .../binutils/2.45.50-2026-01-27_18-02-52-e8108cc5e6fe1748dc6033a297dd2c1c6234de78/bin/ld: input SFrame sections with different format versions prevent .sframe generation
  .../binutils/2.45.50-2026-01-27_18-02-52-e8108cc5e6fe1748dc6033a297dd2c1c6234de78/bin/ld: final link failed
  collect2: error: ld returned 1 exit status

  $ gcc -o /dev/null -Wa,--gsframe=no test.c
  .../binutils/2.45.50-2026-01-27_18-02-52-e8108cc5e6fe1748dc6033a297dd2c1c6234de78/bin/ld: input SFrame sections with different format versions prevent .sframe generation
  .../binutils/2.45.50-2026-01-27_18-02-52-e8108cc5e6fe1748dc6033a297dd2c1c6234de78/bin/ld: final link failed
  collect2: error: ld returned 1 exit status

  $ gcc -o /dev/null -Wl,--discard-sframe test.c

This was extracted from an error I see while building libiberty in
binutils due to the atexit() configure test failing then the fallback to
on_exit() resulting in an error but I also notice it when building
tools/objtool, which is a host tool:

  $ make -skj"$(nproc)" ARCH=x86_64 mrproper defconfig prepare
  .../binutils/2.45.50-2026-01-27_18-02-52-e8108cc5e6fe1748dc6033a297dd2c1c6234de78/bin/ld: input SFrame sections with different format versions prevent .sframe generation
  .../binutils/2.45.50-2026-01-27_18-02-52-e8108cc5e6fe1748dc6033a297dd2c1c6234de78/bin/ld: final link failed
  collect2: error: ld returned 1 exit status
  make[5]: *** [Makefile:127: tools/objtool/objtool] Error 1
  ...

It looks like several distribution ELF objects and libraries on my
system (Arch Linux) have .sframe sections in them, so maybe we still
need -Wl,--discard-sframe? They all appear to be SFrame v2 objects so if
no objects in the build have SFrame v3 sections from -Wa,--gsframe=no,
it seems odd that there is an error but maybe there is something else
going on?

Cheers,
Nathan