Re: [RFC/PATCH 1/1] tools headers arm64: Sync arm64's cputype.h with the kernel sources

[Leo Yan]

On 6/4/24 19:55, Mark Rutland wrote:

[...]

> > Now more and more Arm CPUs support the data source in SPE and share the same
> > data source format. It's not scalable for us to adding every CPU variant
> > into the file util/arm-spe.c.
> >
> > I would like to expose the PMSIDR_EL1.LDS bit (Data source indicator for
> > sampled load instructions) via the 'cap' folder, and then we can save this
> > info into the perf meta data during record phase.
>
> I'd be happy to expose fields from PMSIDR_EL1.
>
> > In the perf report, we can parse the meta data and if the
> > PMSIDR_EL1.LDS bit is set, the tool will parse the data source packet
> > based on the common format.
>
> I don't believe that's right.
>
> PMSIDR_EL1.LDS indicates that the loaded data source field is
> implemented, but even when it is implemented, the format is
> IMPLEMENTATION DEFINED.

Thanks for correction. PMSIDR_EL1.LDS bit is necessary but not 
sufficient for using the common data source format.

> Today, Arm Ltd implementations happen to share a format, but that isn't
> implied by PMSIDR_EL1.LDS, and there's no guarantee that future CPUs
> will all use the same format.
>
> For the moment we'll have to keep adding to this list.

I would like to use an opposite way - we can only maintain CPU variants 
with special data source format, otherwise, all other CPUs use the 
common format.

Thanks,
Leo