Re: [Xen-devel] Xen PVH support in grub2

[Roger Pau Monné]

On Fri, Sep 29, 2017 at 05:02:48PM +0000, Boris Ostrovsky wrote:
> On 09/29/2017 11:51 AM, Roger Pau Monné wrote:
> > On Fri, Sep 29, 2017 at 03:33:58PM +0000, Juergen Gross wrote:
> >> On 29/09/17 17:24, Roger Pau Monné wrote:
> >>> On Fri, Sep 29, 2017 at 02:46:53PM +0000, Juergen Gross wrote:
> >>> Then, I also wonder whether it would make sense for this grub to load
> >>> the kernel using the PVH entry point or the native entry point. Would
> >>> it be possible to boot a Linux kernel up to the point where cpuid can
> >>> be used inside of a PVH container?
> >> I don't think today's Linux allows that. This has been discussed
> >> very thoroughly at the time Boris added PVH V2 support to the kernel.
> > OK, I'm not going to insist on that, but my plans for FreeBSD is to
> > make the native entry point capable of booting inside of a PVH
> > container up to the point where cpuid (or whatever method) can be used
> > to detect the environment.
> >
> > Do you recall what's preventing the native entry point from booting
> > inside of a PVH container? If certain emulated devices not present are
> > needed at early boot we could look into either replacing them with
> > other options available inside of a PVH container, or as a last resort
> > making them available on a PVH container.
> 
> Very much IIRC one of the reasons was the fact that zeropage
> (bootparams) needed to be properly formatted. And the hypercall page
> needs to be set up.

But in this case bootparams is going to be setup by grub, so it should
be fine (just like it's done on bare metal).

Couldn't the hypercall page be setup at some point during early boot?
Not sure if setting it up at the same point HVM does would be fine for
PVH?

Roger.