linux-kernel - Re: [PATCH -v3 0/15] x86: Remove support for TSC-less and CX8-less CPUs

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Message-ID: <CAHk-=wiNkxDCQHvB4L2TyFZp7yBnDiuWW3WNhFLB08u-Y-nEhQ@mail.gmail.com>
Date: Mon, 15 Dec 2025 15:19:58 +1200
From: Linus Torvalds <torvalds@...ux-foundation.org>
To: Brian Gerst <brgerst@...il.com>
Cc: Ingo Molnar <mingo@...nel.org>, linux-kernel@...r.kernel.org, 
	"Ahmed S . Darwish" <darwi@...utronix.de>, Andrew Cooper <andrew.cooper3@...rix.com>, 
	Ard Biesheuvel <ardb@...nel.org>, Arnd Bergmann <arnd@...nel.org>, Borislav Petkov <bp@...en8.de>, 
	Dave Hansen <dave.hansen@...ux.intel.com>, "H . Peter Anvin" <hpa@...or.com>, 
	John Ogness <john.ogness@...utronix.de>, Peter Zijlstra <peterz@...radead.org>, 
	Thomas Gleixner <tglx@...utronix.de>
Subject: Re: [PATCH -v3 0/15] x86: Remove support for TSC-less and CX8-less CPUs

On Mon, 15 Dec 2025 at 14:39, Brian Gerst <brgerst@...il.com> wrote:
>
> Does this also eliminate all processors that do not support CPUID?

I do think it does, as it's also the only way to enumerate both TSC
and CX8, afaik, so the whole "require CX8" effectively also requires
cpuid.

So it probably means we can get rid of all the X86_EFLAGS_ID checks too.

            Linus