On Wed, Aug 10, 2011 at 09:59:41AM +0200, Alexander Graf wrote: > > Am 10.08.2011 um 06:42 schrieb Paul Mackerras <paulus@xxxxxxxxx>: > > > On Tue, Aug 09, 2011 at 06:31:48PM +0200, Alexander Graf wrote: > > > >> Now that Book3S PV mode can also run PAPR guests, we can add a PAPR cap and > >> enable it for all Book3S targets. Enabling that CAP switches KVM into PAPR > >> mode. > > > > Don't we want to enable it only for 64-bit hosts? Trying to run a > > PAPR guest on a 32-bit Book 3S host won't work very well, unless I am > > missing something... > > I agree that it doesn't make sense, but if anything we should > restrict it to 64-bit _guests_. you can also run 32-bit guests on > 64-bit hosts. I had a look in PAPR and I didn't find anything that says the processor has to be 64-bit, so I guess a 32-bit PAPR guest is possible in theory. However, I don't think there are currently any 32-bit PAPR operating systems that would use hcalls. > And so far, we don't have a single interface setting PVR and PAPR > mode at the same time, so you could still enable PAPR with a 64-bit > guest CPU and then switch to a 32-bit CPU. > > It'd be a nightmare to check all configurations on every setter function. > > Unless... > > We could introduce a sanity check function that gets executed every > time we change PVR or enable PAPR. That could set a variable in the > vcpu struct to indicate that the config is ok. We could then check > that on vcpu_run. It's probably not worth worrying about it. The rest of the series looks very nice. Regards, Paul. -- To unsubscribe from this list: send the line "unsubscribe kvm" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
