linux-kernel - Re: [PATCH 0/2] Noinstr fixes for K[CA]SAN with GCOV

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Message-ID: <aUP5j7W8S7koM13M@gate>
Date: Thu, 18 Dec 2025 06:54:39 -0600
From: Segher Boessenkool <segher@...nel.crashing.org>
To: Peter Zijlstra <peterz@...radead.org>
Cc: Marco Elver <elver@...gle.com>, Ard Biesheuvel <ardb@...nel.org>,
        Kees Cook <kees@...nel.org>, Brendan Jackman <jackmanb@...gle.com>,
        Andrey Ryabinin <ryabinin.a.a@...il.com>,
        Alexander Potapenko <glider@...gle.com>,
        Andrey Konovalov <andreyknvl@...il.com>,
        Dmitry Vyukov <dvyukov@...gle.com>,
        Vincenzo Frascino <vincenzo.frascino@....com>,
        kasan-dev@...glegroups.com, linux-kernel@...r.kernel.org,
        linux-toolchains@...r.kernel.org
Subject: Re: [PATCH 0/2] Noinstr fixes for K[CA]SAN with GCOV

Hi!

On Thu, Dec 18, 2025 at 01:18:13PM +0100, Peter Zijlstra wrote:
> On Thu, Dec 18, 2025 at 05:58:44AM -0600, Segher Boessenkool wrote:
> 
> > You might have more success getting the stuff backported to some
> > distro(s) you care about?  Or get people to use newer compilers more
> > quickly of course, "five years" before people have it is pretty
> > ridiculous, two years is at the tail end of things already.
> 
> There is a difference between having and requiring it :/ Our current
> minimum compiler version is gcc-8 or clang-15 (IIRC).

Very much so.  If you have good reasons for requiring it, make sure you
voice that with your backport request!

Nothing we (again, GCC) do is *only* motivated by procedures.  We can do
unusual things in unusual situations.  But you need extraordinary
evidence for why extraordinary things would be needed, of course.  Does
that apply here, you think?

> On the bright side, I think we can be more aggressively with compiler
> versions for debug builds vs regular builds. Not being able to build a
> KASAN/UBSAN/whateverSAN kernel isn't too big of a problem (IMO).

Absolutely.  Just document the feature as needing a recent compiler!


Segher