Re: [Qemu-devel] [libvirt] [PATCH 4/7] qemu: Add monitor APIs to fetch CPUID data from QEMU

[Daniel P. Berrange]

On Thu, Jul 25, 2013 at 04:09:18PM +0200, Andreas Färber wrote:
> Am 25.07.2013 16:00, schrieb Eduardo Habkost:
> > libvirt
> > needs a way to find out how exactly "-machine foo-1.0 -cpu bar" looks
> > different from "-machine foo-1.1 -cpu bar",
> 
> Why? (What's the actual use case?)

It already takes a long time to just probe each QEMU binary, without
expanding that to probe each binary once for each machine type they
include. The idea of 'qemu -M none' was that we'd have a machine type
which did not do any hardware set, to query any aspect of the QEMU
binary capabilities.  If we have to also invoke qemu again with every
other machine type that is a failed design IMHO. It should not be beyond
the realm of possibility to make 'qemu -M none' provide information
about the CPU features for machines/cpus without needing to actually
creating instances of those machines.


Daniel
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