[libvirt] [PATCH v4 2/5] libxl: add support for PVH

[Marek Marczykowski-Górecki]

On Fri, Oct 19, 2018 at 04:19:21PM +0100, Daniel P. Berrangé wrote:
> On Fri, Oct 19, 2018 at 05:10:30PM +0200, Marek Marczykowski-Górecki wrote:
> > On Fri, Oct 19, 2018 at 03:59:03PM +0100, Daniel P. Berrangé wrote:
> > > On Fri, Oct 19, 2018 at 08:53:15AM -0600, Jim Fehlig wrote:
> > > > own head) for either of the two modeling approaches
> > > > 
> > > > https://www.redhat.com/archives/libvir-list/2018-October/msg00214.html
> > > > https://www.redhat.com/archives/libvir-list/2018-October/msg00891.html
> > > 
> > > It has a bad name, but essentially you should consider "ostype" to
> > > refer to the   Hypervisor <-> Guest hardware ABI.
> > 
> > Oh, if that's the case, then indeed separate ostype makes sense. Maybe
> > it worth expanding ostype description somewhere in documentation?

Also, such definition of os type, make "linux" os type for Xen PV even weirder...

> > > Based on what I read, and your 2 links here, PV is clearly a different
> > > hardware ABI from PVH. Guest kernels needs different modifications for
> > > PV vs PVH.
> > > 
> > > Sorry I didn't spot this sooner, and let this go off down the blind
> > > alley of switching based on machine type, when we should have used
> > > the ostype :-(
> > 
> > What machine type should it use then? Still xenpvh, but make all the
> > decisions based on ostype?
> 
> If Xen/QEMU calls the machine type 'xenpvh' then yeah we can still
> use it. 

There is no qemu in the picture, and Xen (libxl) have just one thing:
type, not separate os type and machine type. So, it's only libvirt
specific bit here and we can choose it arbitrarily. As you wrote
below, libvirt can fill it based on os type, so I'll make it "xenpvh".

> By having a distinct ostype, when the XML says "xenpvh" for
> OS type, the XML parser can automatically find the correct machine
> type name from the capabilities data. So mgmt apps using libvirt
> won't need to set the machine type themselves, can just rely on the
> default, after they've set the ostype.

-- 
Best Regards,
Marek Marczykowski-Górecki
Invisible Things Lab
A: Because it messes up the order in which people normally read text.
Q: Why is top-posting such a bad thing?
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