On Mon, 2016-08-01 at 14:32 +0100, Peter Maydell wrote: > > Wouldn't that mean that you'd be unable to use > > > > -cpu foo,pmu=off > > > > if CPU model 'foo' doesn't support a PMU? I'd expect that > > to work. > > The current precedent (has_el3) doesn't work like that: if > foo isn't a CPU which can support EL3 then the property doesn't > exist, and it's an error to try to set it.
Doesn't look like the pmu option works like that on x86, though, unless I'm missing something. I have a guest running with -cpu pentium,pmu=on and I can't see hardware perf events from inside the guest, eg. dmesg reports Performance Events: no PMU driver, software events only. and perf tells me <not supported> instructions <not supported> branches ... I'm not sure whether that's because the PMU is being emulated but the kernel doesn't have a driver for it, or whether it's not being emulated at all. Any way to find out? -- Andrea Bolognani / Red Hat / Virtualization
