On 02/26/10 12:24, Ingo Molnar wrote:
There is a way to query the CPU for 'architectural perfmon' though, via CPUID alone - that is how we set the X86_FEATURE_ARCH_PERFMON shortcut. The logic is:if (c->cpuid_level> 9) { unsigned eax = cpuid_eax(10); /* Check for version and the number of counters */ if ((eax& 0xff)&& (((eax>>8)& 0xff)> 1)) set_cpu_cap(c, X86_FEATURE_ARCH_PERFMON); } But emulating that doesnt solve the problem: as OSs generally dont key their PMU drivers off the relatively new 'architectural perfmon' CPUID detail, but based on much higher level CPUID attributes. (like Intel/AMD)
Right, there is far more to it than just the arch-perfmon feature. They still need to query cpuid 0x0a for counter size, number of counters and stuff like that. Cheers, Jes -- To unsubscribe from this list: send the line "unsubscribe kvm" in the body of a message to majord...@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html
