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

[Arnaldo Carvalho de Melo <acme@kernel.org>]

On Tue, Jun 04, 2024 at 03:34:36PM +0100, Mark Rutland wrote:
> On Tue, Jun 04, 2024 at 10:53:38AM -0300, Arnaldo Carvalho de Melo wrote:
> > On Tue, Jun 04, 2024 at 10:11:22AM +0100, Mark Rutland wrote:
> > > On Mon, Jun 03, 2024 at 03:33:07PM -0300, Arnaldo Carvalho de Melo wrote:
> > > > The changes in the above patch add MIDR_NEOVERSE_V[23] and
> > > > MIDR_NEOVERSE_V1 is used in arm-spe.c, so probably we need to add those
> > > > and perhaps MIDR_CORTEX_X4 to that array? Or maybe we need to leave this
> > > > for later when this is all tested on those machines?
> > > 
> > > Hmm... looking at where that was added this is somewhat misnamed, this
> > > is really saying that these cores use the same IMPLEMENTATION DEFINED
> > > encoding of the source field. That's not really a property of Neoverse
> > > specifically, and I'm not sure what Arm's policy is here going forwards.
> > > 
> > > We should probably rename that to something like
> > > common_data_source_encoding, with a big comment about exactly what it
> > > implies.
> > > 
> > > I would not touch this for now -- someone would have to go audit the
> > 
> > Ok, you mean not touch tools/perf/util/arm-spe.c, right, can I just go
> > ahead and update the copy of that header so that we have a clean (of
> > build warnings) build?
> 
> Yes: update the header, but leave arm-spe.c unchanged. Sorry for not
> being clear!

np
 
> It'd be nice if we could update the commit message to note that we're
> deliberately leaving that as-is.

There is a link tag to this thread and I'll update the message removing
my questions and adding your recommendation.

> Either way:
> 
> Acked-by: Mark Rutland <mark.rutland@arm.com>

Thanks!

- Arnaldo