linux-kernel - Re: [PATCH] ARM: drop cc-option fallbacks for architecture selection

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Date:   Mon, 18 Oct 2021 21:10:58 +0200
From:   Sebastian Andrzej Siewior <sebastian@...akpoint.cc>
To:     Arnd Bergmann <arnd@...nel.org>
Cc:     Russell King <linux@...linux.org.uk>,
        Arnd Bergmann <arnd@...db.de>,
        Antonio Terceiro <antonio.terceiro@...aro.org>,
        Naresh Kamboju <naresh.kamboju@...aro.org>,
        Matthias Klose <doko@...ian.org>, stable@...r.kernel.org,
        Masahiro Yamada <masahiroy@...nel.org>,
        Nathan Chancellor <nathan@...nel.org>,
        Nick Desaulniers <ndesaulniers@...gle.com>,
        linux-arm-kernel@...ts.infradead.org, linux-kernel@...r.kernel.org
Subject: Re: [PATCH] ARM: drop cc-option fallbacks for architecture selection

On 2021-10-18 16:07:12 [+0200], Arnd Bergmann wrote:
…
> Passing e.g. -march=armv6k+fp in place of -march=armv6k would avoid this
> issue, but the fallback logic is already broken because all supported
> compilers (gcc-5 and higher) are much more recent than these options,
> and building with -march=armv5t as a fallback no longer works.
> 
> The best way forward that I see is to just remove all the checks, which
> also has the nice side-effect of slightly improving the startup time for
> 'make'.
> 
…
> This should be safe to apply on all stable kernels, and will be required
> in order to keep building them with gcc-11 and higher.

Yes, please.

> Reported-by: Antonio Terceiro <antonio.terceiro@...aro.org>
> Reported-by: Naresh Kamboju <naresh.kamboju@...aro.org>
> Reported-by: Sebastian Andrzej Siewior <sebastian@...akpoint.cc>
> Link: https://bugs.debian.org/cgi-bin/bugreport.cgi?bug=996419
> Cc: Matthias Klose <doko@...ian.org>
> Cc: stable@...r.kernel.org
> Signed-off-by: Arnd Bergmann <arnd@...db.de>

Reviewed-by: Sebastian Andrzej Siewior <sebastian@...akpoint.cc>

Just booted Debian 9/ Stretch which ships
   gcc version 6.3.0 20170516 (Debian 6.3.0-18) 

to confirm that it fails to compile with the armv5t fallback.

Sebastian