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SubjectRe: [PATCH 3/4] perf, x86: check ucode before disabling PEBS on SandyBridge v3
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On Wed, 2012-06-13 at 13:20 -0700, Andi Kleen wrote:

> +static int check_pebs_quirks(void)
> +{
> + int model = cpu_data(smp_processor_id()).x86_model;
> +
> + /* do not have PEBS to begin with */
> + if (!x86_pmu.pebs)
> + return 0;
> +
> + /*
> + * check ucode version for SNB, SNB-EP
> + */
> + if ((model == 42 && boot_cpu_data.microcode < 0x28) ||
> + (model == 45 && boot_cpu_data.microcode < 0x618)) {

Stephane actually wrote:

"Ok, so to close on this, I tried the 6/6/2012 ucode update on a few
SNB-EP systems.

I got two answers depending on the stepping:
C1 (stepping 6) -> 0x618
C2 (stepping 7) -> 0x70c

So we need to check x86_mask for stepping and adjust the value of
snb_ucode_rev accordingly for model 45."



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