Re: [PATCH 00/20] perf vendors events arm64: Multiple Arm CPUs

[Nick Forrington <nick.forrington@arm.com>]

On 19/05/2022 08:59, John Garry wrote:
> On 18/05/2022 15:14, Robin Murphy wrote:
>>> Sure, we should have these 32b cores supported for ARCH=arm if they 
>>> are supported for ARCH=arm64. But then does it even make sense to 
>>> have A7 support in arch/arm64?
>>
>> That's what I'm getting at. If it is tied to the build target as 
>> you've said above, then there is no point in an AArch64 perf tool 
>> including data for CPUs on which that tool cannot possibly run; it's 
>> simply a waste of space.
>>
>> If there is interest in plumbing in support on AArch32 builds as 
>> well, then I'd still be inclined to have a single arch/arm events 
>> directory, and either do some build-time path munging or just symlink 
>> an arch/arm64 sibling back to it. Yes, technically there are 
>> AArch64-only CPUs whose data would then be redundant when building 
>> for AArch32, 
>
> If size is an issue then we have ways to cut this down, like doing the 
> arch standard events fixup dynamically when running perf tool, or even 
> not describing those events in the JSONs and rely on reading the CPU 
> PMU events folder to learn which of those events are supported.
>
> > but those are
> > such a minority that it seems like an entirely reasonable compromise.
>
> @Nick, Can you drop the 32b core support for arm64? Or, if you really 
> want them, look into ARCH=arm pmu-events support?

No problem - I'll resubmit without the 32b-only CPUs.

Thanks,
Nick