Re: AMU extension v1 support for cortex A76, A77, A78 CPUs

[Vladimir Murzin]

On 11/20/20 8:56 AM, Marc Zyngier wrote:
> On 2020-11-20 04:30, Neeraj Upadhyay wrote:
>> Hi,
>>
>> For ARM cortex A76, A77, A78 cores (which as per TRM, support AMU)
>> AA64PFR0[47:44] field is not set, and AMU does not get enabled for
>> them.
>> Can you please provide support for these CPUs in cpufeature.c?
> 
> If that was the case, that'd be an erratum, and it would need to be
> documented as such. It could also be that this is an optional feature
> for these cores (though the TRM doesn't suggest that).
> 
> Can someone at ARM confirm what is the expected behaviour of these CPUs?

Not a confirmation, but IIRC, these are imp def features, while our cpufeatures
catches architected one.

Cheers
Vladimir

> 
>         M.