Re: [PATCH v6 00/90] x86: Introduce a centralized CPUID data model
Borislav Petkov <[email protected]> Wed, 6 May 2026 16:58:14 +0200
| Newsgroups | dev.linux.lists.x86-cpuid,org.kernel.vger.linux-kernel |
|---|---|
| Message-ID | <20260506145814.GBaftXBsPNE4wgyGB6@fat_crate.local> |
On Wed, May 06, 2026 at 06:59:12AM -0700, H. Peter Anvin wrote: > Sadly, not true; modutila at least does use these numbers due to the brain > damaged way that cpu feature modprobe strings was done. That damn thing! --- Author: Borislav Petkov (AMD) <[email protected]> Date: Wed May 6 16:43:12 2026 +0200 x86/cpufeatures: Document that feature numbers can potentially be an ABI Way too late to change that so document it so that it is written down somewhere and not getting forgotten from time to time and the evil awakening during development of fancy new things can be spared. Reported-by: "H. Peter Anvin" <[email protected]> Signed-off-by: Borislav Petkov (AMD) <[email protected]> diff --git a/arch/x86/include/asm/cpufeatures.h b/arch/x86/include/asm/cpufeatures.h index 1d506e5d6f46..5937e2a30da1 100644 --- a/arch/x86/include/asm/cpufeatures.h +++ b/arch/x86/include/asm/cpufeatures.h @@ -15,6 +15,10 @@ * * When adding new features here that depend on other features, * please update the table in kernel/cpu/cpuid-deps.c as well. + * + * Note that modutils at least does use these numbers due to the brain-damaged + * way that CPU feature modprobe strings was done so the safe assumption is to + * think of those as ABI. For that look at do_x86cpu_entry() in file2alias.c. */ /* Intel-defined CPU features, CPUID level 0x00000001 (EDX), word 0 */ -- Regards/Gruss, Boris. https://people.kernel.org/tglx/notes-about-netiquette