Re: [libvirt] [Qemu-devel] [PATCH 0/9] i386: query-cpu-model-expansion test script

Am 19.01.2017 um 18:45 schrieb Daniel P. Berrange: > On Thu, Jan 19, 2017 at 06:21:22PM +0100, David Hildenbrand wrote: >> >>>> Also think about "query-cpu-model-expansion model=host type=static", >>>> which will primarily be used by libvirt on s390x. There is no way to >>>> expand this into a static cpu model. Faking anything will just hide errors. >>> >>> Yes, static expansion of host model must always return an error >>> if it's not possible to expand. >>> >>>> >>>> If "host" can't be expanded, QEMU has to be treated like there is no CPU >>>> model support (as for older QEMU versions). >>> >>> OK. I will propose a patch updating the query-cpu-model-expansion >>> documentation to be more explicit about it. >> >> The only real alternative I see would be disabling the query-cpu-model-* >> interface completely if KVM support is not available. >> >> This would however mean, that the same QEMU binary would have the >> interface when running under TCG, but not when running under KVM on an >> old KVM version. >> >> That also doesn't really feel right, or what do you think? > > Yeah that really isn't good. query-cpu-model-* needs to work on TCG > and *not* have a dependancy on KVM in that case, since you can be > running TCG s390 on a x86_64 host, so the host CPU is totally irrelevant > for TCG > Actually what I meant was: TCG: query-cpu-model-* interface always provided KVM (with cpu model support): query-cpu-model-* interface provided KVM (without cpu model support): no query-cpu-model-* interface provided This would avoid having to report an error when expanding "host" in the third case (KVM without cpu model support) but would lead to one QEMU binary having a different set of supported qmp calls when called from TCG and KVM.