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From:   Linus Torvalds <torvalds@linux-foundation.org>
Date:   Thu, 14 Jan 2021 10:43:07 -0800
Message-ID: <CAHk-=wjHTpG+gMx9vqrZgo8Uw0NqA2kNjS87o63Zv3=WG2K3zA@mail.gmail.com>
Subject: Re: [PATCH] compiler.h: Raise minimum version of GCC to 5.1 for arm64
To:     Ard Biesheuvel <ardb@kernel.org>
Cc:     Russell King - ARM Linux admin <linux@armlinux.org.uk>,
        Florian Weimer <fweimer@redhat.com>,
        Arnd Bergmann <arnd@kernel.org>,
        "Cc: Android Kernel" <kernel-team@android.com>,
        "Theodore Ts'o" <tytso@mit.edu>,
        Peter Zijlstra <peterz@infradead.org>,
        Catalin Marinas <catalin.marinas@arm.com>,
        Masahiro Yamada <masahiroy@kernel.org>,
        Nick Desaulniers <ndesaulniers@google.com>,
        Linux Kernel Mailing List <linux-kernel@vger.kernel.org>,
        Will Deacon <will@kernel.org>,
        linux-arm-kernel <linux-arm-kernel@lists.infradead.org>
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On Thu, Jan 14, 2021 at 12:18 AM Ard Biesheuvel <ardb@kernel.org> wrote:
>
> So if the arguments are piling up, what is holding us back, other than
> inertia?

I think we can most certainly just try increasing the minimum version
to 5.1 in the next merge window and see.

> Note that banning 4.9 for arm64 and banning it in general should be
> two different changes in any case, as the former will need to be
> backported to -stable kernels as well.

Yes. The arm64 issue is a clear and known bug, plus I suspect gcc-4.9
is ridiculously old in the arm64 ecosystem anyway.

So the arm64 issue is a bug-fix, the follow-up of just upgrading gcc
requirements in general would be a "keep up with the times, and allow
those variable declarations in loops".

            Linus