Re: [PATCH V2 1/8] perf/x86/uncore: Save the unit control address of all units

[Peter Zijlstra]

On Fri, Jun 14, 2024 at 06:46:24AM -0700, kan.liang@xxxxxxxxxxxxxxx wrote:
> From: Kan Liang <kan.liang@xxxxxxxxxxxxxxx>
> 
> The unit control address of some CXL units may be wrongly calculated
> under some configuration on a EMR machine.
> 
> The current implementation only saves the unit control address of the
> units from the first die, and the first unit of the rest of dies. Perf
> assumed that the units from the other dies have the same offset as the
> first die. So the unit control address of the rest of the units can be
> calculated. However, the assumption is wrong, especially for the CXL
> units.

Oh gawd, that's terrible. Was this actually specified, or are we hacking
around a firmware fail?