Re: [PATCH] perf: arm_spe: Support heterogeneous ACPI systems

[Johnny Fan <johnny.fan@cixtech.com>]

On Thu, Oct 15, 2026 at 10:58:10AM -0500, Jeremy Linton wrote:
> I don't think the GICC is sufficient, you have to consider actual
> heterogeneous machines that have differing SPE implementations with the
> same PMSVer, which mean you have to keep the PPTT hetid check, and set
> the mask based on both it and the GSIV. Then, like DT create multiple
> platform devices. Which is true with the current patch as well, the
> hetid still needs to be there even if you have differing PPI's because
> it could have more than two differing implementations.

Following that direction, the question on ACPI is how each registered
SPE device gets its supported_cpus: the platform devices are created
without an fwnode, so platform_get_irq_affinity() falls back to
cpu_possible_mask today, regardless of which CPUs actually implement
SPE. That's the plumbing question I asked Marc about -- would be good
to know if you have a preference here too.

Thanks,

Johnny
>