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From: Linus Torvalds <torvalds@linux-foundation.org>
Date: Sat, 23 Mar 2024 10:06:30 -0700
Message-ID: <CAHk-=wg0cMa6B6OeTtXjx4R-kqxWVHSJ=6y=stRuzk8WduJTsQ@mail.gmail.com>
Subject: Re: [PATCH v4 00/16] x86-64: Stack protector and percpu improvements
To: Brian Gerst <brgerst@gmail.com>, Arnd Bergmann <arnd@arndb.de>
Cc: Uros Bizjak <ubizjak@gmail.com>, linux-kernel@vger.kernel.org, x86@kernel.org, 
	Ingo Molnar <mingo@kernel.org>, Thomas Gleixner <tglx@linutronix.de>, Borislav Petkov <bp@alien8.de>, 
	"H . Peter Anvin" <hpa@zytor.com>, David.Laight@aculab.com
Content-Type: text/plain; charset="UTF-8"

On Sat, 23 Mar 2024 at 09:16, Linus Torvalds
<torvalds@linux-foundation.org> wrote:
>
> And we might as well also do the semi-yearly compiler version review.
> We raised the minimum to 4.9 almost four years ago, and then the jump
> to 5.1 was first for arm64 due to a serious gcc code generation bug
> and then globally in Sept 2021.

Looking at RHEL, I find a page that claims

  RHEL9 : gcc 11.x in app stream
  RHEL8 : gcc 8.x or gcc 9.x in app stream.
  RHEL7 : gcc 4.8.x

so RHEL7 is already immaterial from a kernel compiler standpoint, and
so it looks like at least as far as RHEL is concerned, we could just
jump to gcc 8.1 as a minimum.

RHEL also has a "Developer Toolset" that allows you to pick a compiler
upgrade, so it's not *quite* as black-and-white as that, but it does
seem like we could at some point just pick gcc-8 as a new minimum with
very little pain on that front.

The SLES situation seems somewhat similar, with SLES12 being 4.8.x and
SLES15 being 7.3. But again with a "Development Tools Module" setup.
So that *might* argue for 7.3.

I can't make sense of Debian releases. There's "stable" (bookworm)
that comes with gcc-12.2, but there's oldstable, oldoldstable, and
various "archived" releases still under LTS. I can't even begin to
guess what may be relevant.

I don't think we care that deeply on the kernel side, other than a
"maybe we should be a bit more proactive about raising gcc version
requirements". I don't think we have any huge issues right now with
old gcc versions.

               Linus