* Jaswinder Singh Rajput <jaswinder@xxxxxxxxxx> wrote: > > #define X86_FEATURE_ARCH_PERFMON (3*32+11) /* Intel Architectural PerfMon */ > > should be replaced by > > #define X86_FEATURE_ARCH_PERFMON (3*32+11) /* Performace Monitor */ > > > > All x86 cpus which support performance monitor should set this feature. > > > > Currently X86_FEATURE_ARCH_PERFMON is enabled for >= Intel Core2 > > But Performance monitor is almost supported by all Intel > processors. I am adding few MSRs list for reference to see > complete list please check arch/x86/kernel/cpu/cpu_debug.c I think you are confusing two things: - The 'architectural perfmon' CPU flag, enumerated in CPUID. (this is a relatively new CPUID flag that only Intel CPUs at around Core2 and later will report.) - The concept of 'performance monitoring' - which has been present in various x86 CPUs starting at the original Pentium (P5) 15 years ago or so. The X86_FEATURE_ARCH_PERFMON flag is for the architectural perfmon CPUID feature. If you execute CPUID you'll get that from the CPU - on Core2 and later Intel CPUs. You wont get it on AMD CPUs. You wont get it on earlier Intel CPUs. And since 'Architectural Performance Monitoring' is an Intel only thing, it would not be correct to do as if AMD had the same thing. AMD has something _similar_, but not quite the same. So, the patch from Robert cleans up that area. ( The patch might still be buggy in other ways, but you need to understand its intent and mechanism before being able to argue about other bugs. ) And you need to understand the difference between 'hardware' CPU feature flags, provided by the CPUID instruction, and 'software' CPU feature flags defined by Linux (for the reason of abstracting out certain types of functionality). Ingo -- To unsubscribe from this list: send the line "unsubscribe linux-tip-commits" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
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