On 09.09.2013, at 11:38, Benjamin Herrenschmidt wrote: > On Mon, 2013-09-09 at 11:32 +0200, Alexander Graf wrote: >> On 09.09.2013, at 11:29, Benjamin Herrenschmidt wrote: >> >>> On Mon, 2013-09-09 at 08:06 +0200, Alexander Graf wrote: >>>> I think it's ok to restrict live migration to machines with the same >>>> tb frequency when kvm is enabled. Whether you implement it through a >>>> hardcoded 512Mhz or through a timebase value that gets live migrated >>>> and then compared is up to you - both ways work for me :). >>> >>> The latter might be handy if we want to support migration on 970, though >>> we don't have the TBU40 stuff there so adjusting the TB in the host >>> kernel would be ... problematic. >> >> Well, we could save/restore TB when we enter/exit the guest, no? > > Hard to do without introducing drift...
We could probably quantify the drift through DEC. But I'm personally not too eager to worry about live migration on 970 :). Alex