# Re: \[PATCH v2 3/8\] irqchip/apple-aic: Add cpumasks for E and P cores

- From: Hector Martin \<hidden\>
- Date: 2021-12-12 07:22:09 
- List: linux-arm-kernel
- Page: https://ratatoskr.run/linux-arm-kernel/2021/12/1605153
- Thread: https://ratatoskr.run/linux-arm-kernel/2021/12/1592875/t.md

```text
On 04/12/2021 01.32, Marc Zyngier wrote:
> On Wed, 01 Dec 2021 16:08:13 +0000,
> Mark Rutland [ref] wrote:
>>
>> On Wed, Dec 01, 2021 at 01:49:04PM +0000, Marc Zyngier wrote:
>>> In order to be able to tell the core IRQ code about the affinity
>>> of the PMU interrupt in later patches, compute the cpumasks of the
>>> P and E cores at boot time.
>>>
>>> This relies on the affinity scheme used by the vendor, which seems
>>> to work for the couple of SoCs that are out in the wild.
>>
>> ... but may change at any arbitrary point in future?
>
> Crystal balls are in short supply, sorry! ;-)

Considering Apple seem to rely on this all over the place, I think they probably won't be changing the meaning of Aff2 at least until they decide to come up with SoCs that have 3 types of cores, or something like that :)

But yeah, ultimately this is a guess.

-- 
Hector Martin (marcan@marcan.st)
Public Key: https://mrcn.st/pub

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