Re: [PATCH 3/7] x86: make CX8 usage unconditional

[Arnd Bergmann]

On Sun, Nov 8, 2026, at 21:30, David Laight wrote:
> On Thu,  5 Nov 2026 17:34:34 +0100
> Arnd Bergmann <arnd@xxxxxxxxxx> wrote:
>
>> From: Arnd Bergmann <arnd@xxxxxxxx>
>> 
>> All supported CPUs now provide the cmpxchg8b instruction, so remove
>> all compile-time and runtime checks for its presence and the fallback
>> implementation, to assume it just works.
>
> Is it worth doing a run-time check early on any (trying) to output
> a message and fail to boot?

I think the existing checks in arch/x86/boot/cpucheck.c should be
enough here, as they cover all known pre-586 CPUs and anyone running
some other CPU that we can't detect is already on their own.

      Arnd