Re: [libvirt] [Qemu-devel] [QEMU PATCH 0/3] versioned CPU models / per-machine-type aliases

On Wed, Jul 25, 2012 at 06:43:25PM -0500, Anthony Liguori wrote: > Eduardo Habkost <ehabkost(a)redhat.com&gt; writes: > >> Hi, >> >> This is the first try at a simple system to make the CPU model definitions >> versioned (to allow them to get bug fixes while allowing migration from older >> versions and keeping command-line compatibility), and per- machine-type aliases >> for compatibility. >> >> The lack of CPU model versioning is blocking multiple bug fixes that are >> necessary on CPU model definitions, but can't be included today because they >> would break migration. >> >> Later, after this gets in (or at least gets some feedback), I plan to send a >> proposal for a machine-friendly CPU feature / CPU model probing interface that >> libvirt could use. > > This isn't the right approach. The CPU properties should be exposed as > QOM properties which then allows the machine type globals to be used to > control stuff like this. I would like to use global properties for this, but the obstacles I have found were: - As far as I can see in the code, global properties are usable only by qdev objects, and CPUs were not qdevfied yet

- The per-machine-type properties I need to set are for CPU models, not CPUs. - For example: if we fix the Nehalem CPU model by changing the "level" field, we need to make the pc-1.1 and lower machine-types to keep the old "level" value, but only on the Nehalem CPU model