Amit Shah wrote:
/*
* Check whether the Architectural PerfMon supports
* Unhalted Core Cycles Event or not.
* NOTE: Corresponding bit = 0 in ebx indicates event present.
*/
cpuid(10, &(eax.full), &ebx, &unused, &unused);
if ((eax.split.mask_length <
(ARCH_PERFMON_UNHALTED_CORE_CYCLES_INDEX+1)) ||
(ebx & ARCH_PERFMON_UNHALTED_CORE_CYCLES_PRESENT))
return 0;
So I think it can be done.
Only if the guest kernel (or module accessing those registers) look at
the cpuid output, right? I checked this for the Kaspersky AV on Windows,
the crash bug I was solving and that program doesn't seem to check
cpuid.
The only way to solve all possible cases is to implement the performance
counters MSRs. That's not going to happen in a hurry, we're looking at
making the known cases work.
RHEL 5.3 is based on 2.6.18 and this patch appears to have entered in
2.6.21. I saw this on 5.3 as well.
The snippet I quoted came from RHEL 5.3. It checks cpuid so we should
be able to make it fail gracefully.
--
error compiling committee.c: too many arguments to function
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