Re: [Qemu-devel] [RFC 0/2] GET_EMULATED_CPUID support with "allow-emulation" option

[Eduardo Habkost]

On Thu, Jun 05, 2014 at 06:57:57PM +0200, Paolo Bonzini wrote:
> Il 05/06/2014 18:54, Alexander Graf ha scritto:
> >>
> >>What about:
> >>
> >>- letting "-cpu foo,+emulatedfeature" just work
> >>
> >>- adding emulated=yes that blindly enables all emulated features
> >>
> >>- making "-cpu ...,check" prints a warning for emulated features
> >>unless emulated=yes
> >
> >How about we remove the emulated=yes from this list? Then I'm happy :).
> 
> So:
> 
> - "-cpu foo" doesn't enable any emulated feature

What if "foo" already has movbe in the CPU model definition?

> 
> - "-cpu foo,+movbe" does

What if I want movbe enabled if and only if it is _not_ emulated?

The whole point here is to never ever ever enable an emulated feature
unless it was explicitly what the user wanted.

> 
> - "-cpu foo,check" and "-cpu foo,enforce" print a nice and
> descriptive message if the feature is not available but could be
> enabled as emulated

"nice and descriptive message" needs to be better specified. Messages on
stderr are useless for management software.

Maybe a "emulated-features" property in addition to the existing
"filtered-features" would be useful.

But any of the above changes the fact that this series does not change
the semantics of any "-cpu" option combination, except when not using
the "enforce" flag (which everybody who cares about CPUID data stability
should be already using).

-- 
Eduardo