Re: [Qemu-devel] [PATCH V7 1/2] arm: Add an option to turn on/off vPMU support

[Peter Maydell]

On 21 October 2016 at 22:53, Wei Huang <address@hidden> wrote:
> This patch adds a pmu=[on/off] option to enable/disable vPMU support
> in guest vCPU. This option is only available for cortex-a57/cortex-53/
> host under both KVM mode, but unavailable on ARMv7 and other
> processors. It allows virt tools, such as libvirt, to determine the
> exsitence of vPMU and configure it.

So what actually are we defining as "the PMU exists" here?
The PMU exists in ARMv7 and we actually implement at least some
of it in TCG including for v8 cores (though it is a minimal
architecturally-valid implementation which implements no events,
only the cycle counter).

Should the PMU registers in TCG which we currently provide on
any v7-and-better CPU be hung off ARM_FEATURE_PMU instead ?

thanks
-- PMM