Re: Vanilla Linux 64-bit paravirt guest support

[Mark McLoughlin <markmc@redhat.com>]

On Thu, 2008-04-10 at 10:32 -0400, Michael Abd-El-Malek wrote:
> On Apr 10, 2008, at 10:11 AM, Mark McLoughlin wrote:
> > On Thu, 2008-04-10 at 09:01 -0500, Jeremy Fitzhardinge wrote:
> >> Michael Abd-El-Malek wrote:
> >>> Is 64-bit domU support available anywhere at the moment?  For  
> >>> example,
> >>> what is the status of the git://git.et.redhat.com/xen-pvops-64.git
> >>> tree?  I pulled that tree and tried building 64-bit Xen domU support
> >>> (since this tree allows you to configure the kernel with that
> >>> capability, unlike the vanilla Linux tree).  But compilation  
> >>> failed in
> >>> enlighten.c because xen_smp_ops isn't defined in x86_64.
> >
> > Try building without CONFIG_SMP, it doesn't support that yet.
> 
> Other than SMP support, does the tree represent a fully functional 64- 
> bit PV domU support? 

No, it's a work-in-progress - ia32 emulation is also missing and we're
tracking down a nasty pagetable pinning bug atm.

Even then it would only be on par with 32-bit pv_ops DomU, which itself
doesn't yet have all the Xen features of 2.6.18 tree.

> Does it also allow all hypercalls?  Put another  
> way: is a 64-bit PV domU from that tree less capable than a 64-bit PV  
> domU from Xen's linux-2.6.18.8 tree?

It depends on how you define "less capable" - e.g. some might think a
tree based on a 1.5 year old kernel  is less capable even if it does
have more xen features ... :-)

> >> Redhat have some patches which they're shipping in Fedora 9.  Once  
> >> F9 is
> >> out the door, I'm hoping they'll polish them into an upstreamable  
> >> form.
> >> I don't know whether that git tree represents what's in F9, or if  
> >> that's
> >> somewhere else; at the very least I'd expect you'd be able to pull  
> >> the
> >> patches out of the srpm.
> >
> > Yep, this tree:
> >
> >  http://git.et.redhat.com/?p=xen-pvops-64.git
> >
> > is the work-in-progress x86_64 tree.
> >
> > This tree:
> >
> >  http://git.et.redhat.com/?p=linux-2.6-fedora-pvops.git
> >
> > is what we're actually shipping for F-9. It includes the x86_64 work,
> > but some other paravirt_ops patches too, most of which are queued up
> > upstream.
> 
> Which tree do you recommend I use?

I'd use the xen-pvops-64 tree unless you are specifically wanting to
help with Fedora's kernel-xen packages.

Cheers,
Mark.