Re: [Qemu-arm] [Qemu-devel] [PATCH v6 12/14] target/arm: PMU: Set PMCR.N to 4

[Aaron Lindsay]

On Oct 16 17:09, Richard Henderson wrote:
> On 10/10/18 1:37 PM, Aaron Lindsay wrote:
> > This both advertises that we support four counters and enables them
> > because the pmu_num_counters() reads this value from PMCR.
> > 
> > Signed-off-by: Aaron Lindsay <address@hidden>
> > ---
> >  target/arm/helper.c | 8 ++++----
> >  1 file changed, 4 insertions(+), 4 deletions(-)
> 
> It looks like this should have been folded into patch 10,
> or patch 10 split to include the code changes that go with
> these comment changes.

By setting PMCR.N to 4, this commit is what causes all the previous
implementation of non-PMCCNTR counters to become usable by the guest -
both because the OS can now detect their presence in PMCR, and because
the system registers used to setup/access the counters are gated on
pmu_num_counters(), which uses PMCR.N to determine if a counter is
implemented.

That said, I'm not against merging the two patches if you feel that is
cleaner.

-Aaron