Re: [PATCH] perf/x86/intel: fix ICL/SPR INST_RETIRED.PREC_DIST encodings

[Peter Zijlstra]

On Wed, Oct 13, 2021 at 05:12:14PM -0700, Stephane Eranian wrote:
> This patch fixes the encoding for INST_RETIRED.PREC_DIST as published by Intel
> (download.01.org/perfmon/) for Icelake. The official encoding
> is event code 0x00 umask 0x1, a change from Skylake where it was code 0xc0
> umask 0x1.
> 
> With this patch applied it is possible to run:
> $ perf record -a -e cpu/event=0x00,umask=0x1/pp .....
> 
> Whereas before this would fail.
> 
> To avoid problems with tools which may use the old code, we maintain the old
> encoding for Icelake.

Uuuuhhhhh.. but we 'stole' event=0x00 for the fake events. There must
not be actual hardware events there or we're in trouble. I thought Intel
knew that, I'm sure I told them that.