Am 27.08.2014 17:42, schrieb Eduardo Habkost: > On Wed, Aug 27, 2014 at 04:33:54PM +0200, Paolo Bonzini wrote: >> Il 27/08/2014 16:05, Eduardo Habkost ha scritto: >>> On Wed, Aug 27, 2014 at 03:36:51PM +0200, Paolo Bonzini wrote: >>>> Il 26/08/2014 20:01, Eduardo Habkost ha scritto: >>>>> So maybe that's good news, as things can be simpler if we make both TCG >>>>> and KVM have similar behavior: >>>>> >>>>> * qemu64: a conservative default that should work out of the box on >>>>> most systems, for both TCG and KVM. That's already the current status, >>>>> we just need to document it. >>>>> >>>>> * -cpu host: for people who want every possible feature to be enabled >>>>> (but without cross-version live-migration support). We can easily add >>>>> support for "-cpu host" to TCG, too. >>>> >>>> This means that "-cpu host" has different meanings in KVM and TCG. Is >>>> that an advantage or a disadvantage? >>> >>> It is the same meaning to me: "enable everything that's possible, >>> considering what's provided by the underlying accelerator". The "host" >>> name is misleading, though, because on KVM it is close to the host CPU, >>> but on TCG it depends solely on TCG's capabilities. >> >> True. It's not very intuitive, but it is the same concept for processor >> capabilities. >> >> Though for some leaves that do not correspond to processor capabilities, >> "-cpu host" does set them to the host values. This is not just the >> cache model, but also the family/model/stepping/vendor. >> >> For the TCG case, when running on a Nehalem it would be weird to see a >> Nehalem guest with SMAP or ADOX support... I'm not sure it would even >> work to have SVM with an Intel vendor. :) > > In that case, the best family/model/stepping/vendor choice depends on > TCG capabilities (defined at compile time), not on the host CPU. > > ...and that proves your point: if we aren't even using the host CPU > family/model/stepping, calling it "-cpu host" doesn't make much sense. > If it is so different from the host model, we can call it "qemu64" (and > do as you suggests below). Might that be an opportunity to reconsider a -cpu best or so, independent of its implementation, to avoid "host"? Regards, Andreas -- SUSE LINUX Products GmbH, Maxfeldstr. 5, 90409 Nürnberg, Germany GF: Jeff Hawn, Jennifer Guild, Felix Imendörffer; HRB 16746 AG Nürnberg -- 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
