Re: [Minios-devel] [UNIKRAFT] Xen PVH platform

[Wei Liu <wei.liu2@xxxxxxxxxx>]

On Tue, Mar 12, 2019 at 05:03:15PM +0100, Marek Marczykowski-Górecki wrote:
> On Tue, Mar 12, 2019 at 08:52:11AM +0000, Simon Kuenzer wrote:
> > Hey Marek,
> > 
> > yes, you are right. We are supporting only PV on x86 for now. The pieces of 
> > PVH/HVM that we have left are left-overs from taking some of the code from 
> > Mini-OS. In general, we would be happy to have also PVH support.
> > So far, our focus was on increasing functionality with libraries and 
> > drivers in order to make the project more useful for most people. However, 
> > if you have time, we are happy to receive patches to enable PVH ;-) . Let 
> > us know if you are interested.
> 
> Yes! Actually, I already have something that boots on PVH. It's quite
> specific, as it's plugged into MirageOS, which use unikraft as just one
> of its packages right now. It's very much work in progress state.
> 
> > The most natural way for Unikraft would be to build two Xen binaries: One 
> > for PV and another one for PVH. The idea is that you get the most optimized 
> > image for your execution environment. This way you would avoid impacts 
> > because of the two implementations. You also would not require a detection 
> > at runtime.
> 
> I see, that makes sense. On the other hand, passing CONFIG_PARAVIRT
> through multiple layers may be problematic, so I think it may be worth
> having some universal binary. But I'll leave it for some undefined
> future.
> 
> Anyway, even without having PV+PVH binary, I have one important question:
> how start_info_t and HYPERVISOR_start_info should looks like? Right now
> I've made it an union (with "pv" under CONFIG_PARAVIRT and "hvm" under
> CONFIG_XEN_HVMLITE). This require all the places using this symbol to be
> changed. Some alternative would be to have a separate symbol like
> HYPERVISOR_start_info_hvm for the other start info structure and keep
> HYPERVISOR_start_info unchanged (or under CONFIG_PARAVIRT). While
> changing everything using HYPERVISOR_start_info is some pain, IMO it's
> better than forgetting something and erroneously using (uninitialized)
> PV version on PVH...

Off topic: can I suggest you s/HVMLITE/PVH/ ?

There has been enough confusion on what means what. :-)

Wei.

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