[libvirt] [PATCH 04/22] virsh: Enhance documentation of cpu-models command

[Jiri Denemark]

On Thu, May 24, 2018 at 11:05:08 +0200, Kashyap Chamarthy wrote:
> On Wed, May 23, 2018 at 09:09:28PM +0200, Jiri Denemark wrote:
> > On Wed, May 23, 2018 at 16:53:37 +0200, Kashyap Chamarthy wrote:
> > > On Wed, May 23, 2018 at 02:43:23PM +0200, Jiri Denemark wrote:
> > > > On Wed, May 23, 2018 at 13:08:51 +0200, Kashyap Chamarthy wrote:
> > > > > On Wed, May 16, 2018 at 10:39:23AM +0200, Jiri Denemark wrote:
> > > > > > Signed-off-by: Jiri Denemark <jdenemar at redhat.com>
> > > > > > ---
> > > > > >  tools/virsh.pod | 8 +++++++-
> > > > > >  1 file changed, 7 insertions(+), 1 deletion(-)
> > > 
> > > [...]
> > > 
> > > > > > +Moreover, for some architectures libvirt does not know any CPU models and
> > > > > > +the usable CPU models are only limited by the hypervisor. 
> > > > > 
> > > > > Wonder if it is worth adding a small example for the above.
> > > > 
> > > > An example for what exactly?
> > > 
> > > I meant an example of a usable CPU model that libvirt doesn't know for
> > > the said architecture(s).  Maybe it's not worth it; not quite sure.
> > 
> > The usable models are all models accepted by hypervisor for that
> > architecture. So, e.g., libvirt won't list any CPU model for aarch64
> > when you call "virsh cpu-models aarch64", it will just print "all CPU
> > models are accepted" and "virsh domcapabilities --arch aarch64" will
> > show a very long list of CPU models libvirt would actually accept.
> > Similarly for s390x.
> 
> Ah, that is clearer; thank you.  So if you think it is worth it, maybe
> adjust your doc patch to a variant of the following:
> 
>     Moreover, for some architectures libvirt does not know any CPU
>     models and the usable CPU models are only limited by the hypervisor
>     (e.g. to enumerate a list of acceptable CPU models for AArch64, use
>     `virsh domcapabilities --arch aarch64`; likewise for 's390x').

So how about

    Print the list of CPU models known by libvirt for the specified
    architecture. Whether a specific hypervisor is able to create a
    domain which uses any of the printed CPU models is a separate
    question which can be answered by looking at the domain capabilities
    XML returned by B<domcapabilities> command. Moreover, for some
    architectures libvirt does not know any CPU models and the usable
    CPU models are only limited by the hypervisor. This command will
    print that all CPU models are accepted for these architectures and
    the actual list of supported CPU models can be checked in the domain
    capabilities XML.

Jirka