Re: [Xen-devel] hypercall_xlat_continuation()

[Ian Campbell <Ian.Campbell@xxxxxxxxxx>]

On Sat, 2009-05-23 at 06:17 -0400, Keir Fraser wrote:
> On 22/05/2009 22:58, "Mukesh Rathor" <mukesh.rathor@xxxxxxxxxx> wrote:
> 
> > Ok. Even if I can't make it clearer, at least I'll add few lines of comments
> > explaining what's going on, after (and if) I figure it out.
> > 
> > Jan,
> > 
> > It seems assumption is made that a 64bit dom0 will not have a 32bit app 
> > making
> > hypercall?
> > 
> > BUG_ON(*reg != (unsigned int)*reg);  <====
> 
> You know that all the 'xlat' stuff in Xen is for 32-bit guests running on
> 64-bit hypervisor, right? 64-bit dom0 would never execute this logic.

It's worth noting though that I don't believe a 32 bit dom0 toolstack on
a 64 bit kernel on a 64 bit hypervisor will work. In particular the
privcmd "make a hypercall" ioctl doesn't do any compat translation so 32
bit xend and friends can't make hypercalls that way and I think the
MMAPBATCH privcmd doesn't work either.

I'm sure there are other cases too (blktap user<->kernel ring layout
maybe?).

Ian.



_______________________________________________
Xen-devel mailing list
Xen-devel@xxxxxxxxxxxxxxxxxxx
http://lists.xensource.com/xen-devel