Re: [libvirt] [PATCH] cpu: Add support for CPU vendor

On Mon, Jul 19, 2010 at 02:40:40PM +0200, Jiri Denemark wrote: > > > By specifying <vendor> element in CPU requirements a guest can be > > > restricted to run only on CPUs by a given vendor. Host CPU vendor is > > > also specified in capabilities XML. > > > > > > The vendor is checked when migrating a guest but it's not forced, i.e., > > > a guest configured without <vendor> element can be freely migrated. > ... > > > src/cpu/cpu_map.xml | 6 + > > > > Why did you add <vendor> tags to several of the models there? Does qemu > > (-no-kvm) have any problem emulating athlon on an Intel host? > > Honestly, I don't know if qemu has any problems emulating them but it doesn't > really matter. The <vendor> emelement in cpu_map.xml is used when libvirt > decides what model should be used for describing host CPU. > > > And how about adding policy='disable' attribute, so that I can ask > > virConnectCompareCPU to ignore this particular incompatibility, as I do > > with <feature> items? > > Just don't use <vendor> tag in your XML. > > In other words, if you specify <vendor> in domain XML (or it's cpu fragment > used by virConnectCompareCPU) and your host CPU is made by different vendor, > the CPUs won't match. If you don't specify <vendor>, you don't care about the > vendor and neither does libvirt. > > I hope it's more clear now. I wanted to (ab)use virConnectCompareCPU to roughly tell a certain cpu model (say athlon) can be emulated on my host. I now see that this is not going to happen, and I'll have to do my own feature set comparison.