arch/x86/Makefile REALMODE_CFLAGS needs -std=gnu11 with recent GCC versions

arch/x86/Makefile REALMODE_CFLAGS needs -std=gnu11 with recent GCC versions

[Dennis Clarke]

Code fix for due to https://bugzilla.kernel.org/show_bug.cgi?id=220294

The summary is that recent GCC versions ( 15.1.0 today ) will assume C23
spec compliance and get upset with ye old A20 address line code bits.

This problem exists previous to the 6.12.35 release tarballs and is
fixed with commit b3bee1e7c3f2b1b77182302c7b2131c804175870 applied.

The newer GCC revisions will be quite popular soon enough and this may
bite people when that happens.

-- 
--
Dennis Clarke
RISC-V/SPARC/PPC/ARM/CISC
UNIX and Linux spoken
Beard and Suspenders installed

Re: arch/x86/Makefile REALMODE_CFLAGS needs -std=gnu11 with recent GCC versions

[Borislav Petkov]

+ stable folks.

On Sun, Jun 29, 2025 at 11:15:13AM -0400, Dennis Clarke wrote:
> 
> Code fix for due to https://bugzilla.kernel.org/show_bug.cgi?id=220294
> 
> The summary is that recent GCC versions ( 15.1.0 today ) will assume C23
> spec compliance and get upset with ye old A20 address line code bits.
> 
> This problem exists previous to the 6.12.35 release tarballs and is
> fixed with commit b3bee1e7c3f2b1b77182302c7b2131c804175870 applied.
> 
> The newer GCC revisions will be quite popular soon enough and this may
> bite people when that happens.

I don't know what the rules are for building 6.1-stable with gcc-15 but if
they do that, then 6.1 will need to pick up the abovementioned commit:

  b3bee1e7c3f2 ("x86/boot: Compile boot code with -std=gnu11 too")

Thx.

-- 
Regards/Gruss,
    Boris.

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