Re: [Qemu-devel] [PATCH V7 0/2] Add option to configure guest vPMU

[Peter Maydell]

On 25 October 2016 at 16:26, Peter Maydell <address@hidden> wrote:
> On 25 October 2016 at 08:33, Andrew Jones <address@hidden> wrote:
>> Yes, I prefer it to not being able to easily switch a command line from
>> KVM to TCG. Granted, right now we mostly need to run with -cpu host for
>> KVM, which also needs to be switched for TCG. However that will hopefully
>> change with Shannon's work.
>
> If the TCG default is different from the KVM default then you
> will have problems with switching it anyway, because it will
> silently change behaviour underfoot. I think we should avoid that...

So here's my suggestion: we should just not worry about printing
a warning for not actually honouring the "please give me a PMU"
flag under TCG. At some point we'll actually implement it,
at which point the problem goes away. In the meantime (a) not
providing a PMU and not bothering to say so is what we were
doing before, and (b) there's lots of bits of the CPU that we
don't actually yet implement in TCG but which will appear as
we fix bugs in the emulation.

thanks
-- PMM