Re: [Qemu-devel] [patch 2/2] target-i386: block migration and savevm if invariant tsc is exposed

[Eduardo Habkost]

On Tue, Apr 22, 2014 at 06:27:59PM -0300, Marcelo Tosatti wrote:
> On Tue, Apr 22, 2014 at 05:38:07PM -0300, Eduardo Habkost wrote:
> > On Tue, Apr 22, 2014 at 04:10:44PM -0300, Marcelo Tosatti wrote:
> > > Invariant TSC documentation mentions that "invariant TSC will run at a
> > > constant rate in all ACPI P-, C-. and T-states".
> > > 
> > > This is not the case if migration to a host with different TSC frequency 
> > > is allowed, or if savevm is performed. So block migration/savevm.
> > > 
> > > Also do not expose invariant tsc flag by default.
> > 
> > What do you mean "do not expose invtsc by default", exactly? It is
> > already not exposed by default because the default CPU model is qemu64
> > and qemu64 doesn't have it enabled.
> 
> Should be "do not expose invtsc by default with -cpu host".
> 
> Since it blocks migration, i considered it a special flag that should 
> be set when user is aware that migration is going to be blocked.
> 
> Makes sense?

Not for "-cpu host". If somebody needs migration to work, they shouldn't
be using "-cpu host" anyway (I don't know if you have seen the other
comments in my message?).

-- 
Eduardo