Messages in this thread | | | Date | Fri, 5 May 2023 09:42:36 -0700 | Subject | Re: [tip: perf/core] x86/cpu: Add helper function to get the type of the current hybrid CPU | From | Dave Hansen <> |
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On 4/20/21 03:46, tip-bot2 for Ricardo Neri wrote: > +#define X86_HYBRID_CPU_TYPE_ID_SHIFT 24 > + > +/** > + * get_this_hybrid_cpu_type() - Get the type of this hybrid CPU > + * > + * Returns the CPU type [31:24] (i.e., Atom or Core) of a CPU in > + * a hybrid processor. If the processor is not hybrid, returns 0. > + */ > +u8 get_this_hybrid_cpu_type(void) > +{ > + if (!cpu_feature_enabled(X86_FEATURE_HYBRID_CPU)) > + return 0; > + > + return cpuid_eax(0x0000001a) >> X86_HYBRID_CPU_TYPE_ID_SHIFT; > +}
Hi Folks,
Sorry to dredge up an old thread. But, where does this information about "If the processor is not hybrid, returns 0." come from?
What is there to keep cpuid_eax(0x0000001a) from having 0x0 in those bits? Seems to me like 0 is theoretically a valid hybrid CPU type. Right?
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