linux-kernel - Re: [RFC PATCH 02/28] Documentation: Bump minimum GCC version to 8.1

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Message-Id: <c4868f63-b688-4489-a112-05bf04280bde@app.fastmail.com>
Date: Wed, 25 Sep 2024 15:58:38 +0000
From: "Arnd Bergmann" <arnd@...db.de>
To: "Ard Biesheuvel" <ardb+git@...gle.com>, linux-kernel@...r.kernel.org
Cc: "Ard Biesheuvel" <ardb@...nel.org>, x86@...nel.org,
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Subject: Re: [RFC PATCH 02/28] Documentation: Bump minimum GCC version to 8.1

On Wed, Sep 25, 2024, at 15:01, Ard Biesheuvel wrote:
> From: Ard Biesheuvel <ardb@...nel.org>
>
> Bump the minimum GCC version to 8.1 to gain unconditional support for
> referring to the per-task stack cookie using a symbol rather than
> relying on the fixed offset of 40 bytes from %GS, which requires
> elaborate hacks to support.
>
> Signed-off-by: Ard Biesheuvel <ardb@...nel.org>
> ---
>  Documentation/admin-guide/README.rst | 2 +-
>  Documentation/process/changes.rst    | 2 +-
>  2 files changed, 2 insertions(+), 2 deletions(-)

Acked-by: Arnd Bergmann <arnd@...db.de>

As we discussed during plumbers, I think this is reasonable,
both the gcc-8.1 version and the timing after the 6.12-LTS
kernel.

We obviously need to go through all the other version checks
to see what else can be cleaned up. I would suggest we also
raise the binutils version to 2.30+, which is what RHEL8
shipped alongside gcc-8. I have not found other distros that
use older binutils in combination with gcc-8 or higher,
Debian 10 uses binutils-2.31.
I don't think we want to combine the additional cleanup with
your series, but if we can agree on the version, we can do that
in parallel.

FWIW, here are links to the last few times we discussed this,
and there are already has a few other things that would
benefit from more modern compilers:

https://lore.kernel.org/lkml/dca5b082-90d1-40ab-954f-8b3b6f51138c@app.fastmail.com/
https://lore.kernel.org/lkml/CAFULd4biN8FPRtU54Q0QywfBFvvWV-s1M3kWF9YOmozyAX9+ZQ@mail.gmail.com/
https://lore.kernel.org/lkml/CAK8P3a1Vt17Yry_gTQ0dwr7_tEoFhuec+mQzzKzFvZGD5Hrnow@mail.gmail.com/

     Arnd