* Michael S. Tsirkin <m...@redhat.com> wrote:
> On Sandy bridge CPUs with old microcode, PEBs
> fails and suggests a microcode update.
> Print out the required and the actual revision to
> make it easier to figure out what's wrong.
>
> Signed-off-by: Michael S. Tsirkin <m...@redhat.com>
> ---
> arch/x86/kernel/cpu/perf_event_intel.c | 2 ++
> 1 file changed, 2 insertions(+)
>
> diff --git a/arch/x86/kernel/cpu/perf_event_intel.c
> b/arch/x86/kernel/cpu/perf_event_intel.c
> index f31a165..81f2789 100644
> --- a/arch/x86/kernel/cpu/perf_event_intel.c
> +++ b/arch/x86/kernel/cpu/perf_event_intel.c
> @@ -2105,6 +2105,8 @@ static int intel_snb_pebs_broken(int cpu)
> }
> }
>
> + pr_info("PEBS checking: microcode 0x%x min legal 0x%x\n",
> + cpu_data(cpu).microcode, rev);
That's not a very informative message though.
Something like:
"x86/perf/intel: PEBS turned off due to too old microcode version 0x%x\n"
"x86/perf/intel: Minimum required microcode version for PEBS: 0x%x\n"
would work better I think.
Also, only output this once, and only output it if the check
_fails_.
> return (cpu_data(cpu).microcode < rev);
Btw., please also fix the return statement, it doesn't need
parentheses.
Thanks,
Ingo
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