Re: [Xen-devel] grant tables and HVM+PV

[John Levon <levon@xxxxxxxxxxxxxxxxx>]

On Fri, Mar 28, 2008 at 05:03:17PM +0000, Keir Fraser wrote:

> > Has broken our HVM PV drivers. Previously we were using:
> > 
> > 520         if ((HYPERVISOR_grant_table_op(GNTTABOP_setup_table, pset, 1) !=
> > 0) ||
> > 521             (pset->status != 0)) {
> > 
> > even on HVM. Now, this isn't actually necessary (stuff works fine with
> > the call nop'd out, presumably due to the auto-sizing), but I wonder why the
> > only grant op allowed is _query_size? IE what's the status of grant
> > table code on HVM/PV? Is it just disabled because no compat audit has
> > been done, or what?
> 
> Most of the mapping calls wouldn't work at all.

OK. I think we were effectively ending up with a call that did nothing
but did it quietly and now we're getting back (the correct) ENOSYS.
Clearly our bug but it wasn't quite obvious what was supposed to work.

> Query_size() could probably be simply given a stub implementation for
> HVM that returns all is good.

It already is, I think?

regards
john

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