Re: [Qemu-devel] [PATCH v3 2/2] i386/kvm: lower requirements for Hyper-V frequency MSRs exposure

[Eduardo Habkost <ehabkost@redhat.com>]

On Wed, Mar 21, 2018 at 08:17:55PM +0300, Roman Kagan wrote:
> On Wed, Mar 21, 2018 at 05:17:38PM +0100, Vitaly Kuznetsov wrote:
> > (What I'm worried about with all our hv_* knobs is that more of them we
> > have easier it is to assemble some frankenstien which won't look like
> > any existing Hyper-V version; we're probably not doing a very good job
> > tesing all possible hv_* combinations as people probably use 'all or
> > nothing'. In case we end up finding a bug in Windows with some weird
> > hv_* combination it's unlikely Microsoft will bother fixing at as it
> > doesn't reproduce on any existent Hyper-V version.
> 
> I agree that this is getting cumbersome, but, given that features get
> added incrementally and we need to be able to maintain backwards
> compatibility, I'm afraid this is unavoidable.
> 
> > That said, it would be great to eventually have something like
> > 'hv_ws2012r2' property making us look exactly the same real WS2012R2
> > looks like. Unfortunatelly, I'm unsure about a path to get there).
> 
> I'm tempted to delegate this -- combining features into user-friendly
> sets -- to the upper layers: libvirt or even something on top of it.

Sounds simpler to me, otherwise we would need a mechanism to tell
the upper layers which of those named are usable on the current
host.

-- 
Eduardo