On Wed, Mar 10, 2021 at 08:37:37AM -0800, kan.li...@linux.intel.com wrote:
> From: Ricardo Neri <ricardo.neri-calde...@linux.intel.com>
>
> Add feature enumeration to identify a processor with Intel Hybrid
> Technology: one in which CPUs of more than one type are the same package.
> On a hybrid processor, all CPUs support the same homogeneous (i.e.,
> symmetric) instruction set. All CPUs enumerate the same features in CPUID.
> Thus, software (user space and kernel) can run and migrate to any CPU in
> the system as well as utilize any of the enumerated features without any
> change or special provisions. The main difference among CPUs in a hybrid
> processor are power and performance properties.
>
> Cc: Andi Kleen <a...@linux.intel.com>
> Cc: Kan Liang <kan.li...@linux.intel.com>
> Cc: "Peter Zijlstra (Intel)" <pet...@infradead.org>
> Cc: "Rafael J. Wysocki" <rafael.j.wyso...@intel.com>
> Cc: "Ravi V. Shankar" <ravi.v.shan...@intel.com>
> Cc: Srinivas Pandruvada <srinivas.pandruv...@linux.intel.com>
> Cc: linux-kernel@vger.kernel.org
> Reviewed-by: Len Brown <len.br...@intel.com>
> Reviewed-by: Tony Luck <tony.l...@intel.com>
> Signed-off-by: Ricardo Neri <ricardo.neri-calde...@linux.intel.com>
> ---
> Changes since v1 (as part of patchset for perf change for Alderlake)
> * None
>
> Changes since v1 (in a separate posting):
> * Reworded commit message to clearly state what is Intel Hybrid
> Technology. Stress that all CPUs can run the same instruction
> set and support the same features.
> ---
> arch/x86/include/asm/cpufeatures.h | 1 +
> 1 file changed, 1 insertion(+)
>
> diff --git a/arch/x86/include/asm/cpufeatures.h
> b/arch/x86/include/asm/cpufeatures.h
> index cc96e26d69f7..e7cfc9eedf8d 100644
> --- a/arch/x86/include/asm/cpufeatures.h
> +++ b/arch/x86/include/asm/cpufeatures.h
> @@ -374,6 +374,7 @@
> #define X86_FEATURE_MD_CLEAR (18*32+10) /* VERW clears CPU buffers */
> #define X86_FEATURE_TSX_FORCE_ABORT (18*32+13) /* "" TSX_FORCE_ABORT */
> #define X86_FEATURE_SERIALIZE (18*32+14) /* SERIALIZE
> instruction */
> +#define X86_FEATURE_HYBRID_CPU (18*32+15) /* This part has
> CPUs of more than one type */
/* "" This ...
unless you have a valid use case for "hybrid_cpu" being present there.
Thx.
--
Regards/Gruss,
Boris.
https://people.kernel.org/tglx/notes-about-netiquette
