Re: [PATCH v3 00/17] Introducing Linux root partition support for Microsoft Hypervisor

Wei Liu
2020-12-15T16:44:11Z

On Tue, Dec 15, 2020 at 04:25:03PM +0100, Enrico Weigelt, metux IT consult wrote:
> On 03.12.20 00:22, Wei Liu wrote:
>
> Hi,
>
> > I don't follow. Do you mean reusing /dev/kvm but with a different set of
> > APIs underneath? I don't think that will work.
>
> My idea was using the same uapi for both hypervisors, so that we can use
> the same userlands for both.
>
> Are the semantis so different that we can't provide the same API ?

We can provide some similar APIs for ease of porting, but can't provide
1:1 mappings. By definition KVM and MSHV are two different things. There
is no goal to make one ABI / API compatible with the other.

>
> > In any case, the first version of /dev/mshv was posted a few days ago
> > [0]. While we've chosen to follow closely KVM's model, Microsoft
> > Hypervisor has its own APIs.
>
> I have to admit, I don't know much about hyperv - what are the main
> differences (from userland perspective) between hyperv and kvm ?
>

They have different architecture and hence different ways to deal with
things. The difference will inevitably make its way to userland.

Without going into all the details, you can have a look how Xen and KVM
differ architecturally. That will give you a pretty good idea on the
differences.

Wei.

>
> --mtx
>
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> Enrico Weigelt, metux IT consult
> Free software and Linux embedded engineering
> info@metux.net -- +49-151-27565287