On Fri, Jun 17, 2016 at 05:28:03PM +0200, Paolo Bonzini wrote: > On 17/06/2016 17:19, Eduardo Habkost wrote: > > > > So, what happens if the guest play tricks in bits 40-45 when QEMU > > > > sets the limit to 40 but we are running in a 46-bit host? Is it > > > > really a problem? I assumed it would be safe. > > > > > > The guest expects a "reserved bit set" page fault, but doesn't get one. > > > > Wait, are you talking about migration only, or are you really > > talking about running current QEMU (hardcoded to 40) on a 46-bit > > host? I'm not talking about migration, above. > > I'm talking about both. :( > > > We really can't emulate a 40-bit machine in a 46-bit host? I > > didn't expect that. > > Unfortunately that's the case. :(
OK, so please ignore all my suggestions about choosing reasonable defaults based on VM size, etc. Now all options look bad, and we need to choose the least harmful as the default... I need to re-read this thread to be able to give an opinion. -- Eduardo
