Re: [libvirt] Is seems necessary to pass "migratable=no/yes" to qemu.

On 09/25/2014 04:31 AM, zhang bo wrote: > On 2014/9/24 19:49, Ján Tomko wrote: >> I think the simplest fix for host-passthrough would be to apply the same >> filter host-model has. >> >> But since using invtsc with host-passthrough requires both +invtsc and >> migratable=no, so we'd need to either add a 'migratable' option to >> host-passthrough (this would skip the filter and add migratable=on), or allow >> fine-tuning the features for host-passthrough too. >> >> Jan >> > > Additional to the 2 suggestions, will that be OK to remove the codes in qemuProcessVerifyGuestCPU that checks whether the vm->def has > invtsc flag while qemu doesn't? > > - if (STREQ(feature->name, "invtsc") && > - !cpuHasFeature(guestcpu, feature->name)) { > - virReportError(VIR_ERR_CONFIG_UNSUPPORTED, "%s", > - _("host doesn't support invariant TSC")); > - goto cleanup; > - } Without this check, the feature would be quietly discarded by QEMU if the host kernel or host CPU does not support this feature. I think it's better to leave "invtsc" out when we're generating the cpu definition for host-passthrough, as we do for host-model. Jan > > Removing these codes, plus with the solution that "add 'migratable' option to host-passthrough", it seems the problem would > be gone, and invtsc would not be so 'distinctive' in libvirt any more. >