Re: [Qemu-devel] [qom/qom-cpu PATCH] i386: invtsc migration blocker is redudant

[Marcelo Tosatti]

On Wed, May 28, 2014 at 01:25:38PM -0300, Eduardo Habkost wrote:
> On Wed, May 28, 2014 at 11:14:14AM +0200, Juan Quintela wrote:
> > Eduardo Habkost <address@hidden> wrote:
> > > On Tue, May 27, 2014 at 11:39:20AM -0300, Marcelo Tosatti wrote:
> > >> 
> > >> Migration blocker is redudant: blocking savevm is sufficient.
> > >> 
> > >
> > > Removing the redundancy looks welcome, but at the same time the
> > > migrate_add_blocker() call ensured we had a clearer error message (I
> > > mean: if we did mention invtsc in the error message, which we still
> > > don't, but should).
> > >
> > > I am not familiar with how we deal with savevm/migration errors, so I
> > > don't know what's best here. Juan, do you have any suggestions?
> > 
> > 
> > CHange unmigratable to Error * and add the message there?  First one
> > wins (or a way to combine them?).
> > 
> > Really I don't have a better idea.
> 
> My first question is: why migrate_add_blocker() doesn't affect savevm?
> On which cases does it make sense to block migration only, and on which
> cases does it make sense to block migration and savevm?

Can't see any case in which blocking only migration makes sense.

1) savevm on source
2) loadvm on destination

Is similar to migration regarding the state thats available on
destination. 

Thinko?