Re: Xen 4.18 pvshim console issue (with patch)

[Manuel Bouyer <bouyer@xxxxxxxxxxxxxxx>]

On Wed, Oct 18, 2023 at 04:18:26PM +0200, Michal Orzel wrote:
> Hi,
> 
> On 18/10/2023 15:29, Jan Beulich wrote:
> > 
> > 
> > On 18.10.2023 12:38, Manuel Bouyer wrote:
> >> Hello,
> >> With Xen 4.18, a PV domain running under pvshim doesn't get console input.
> >> This is because the domain id in pvshim isn't 0 (and on x86 max_init_domid 
> >> is
> >> hardwired to 0), so console_input_domain() will never select that domain
> >> as input.
> >>
> >> The attached patch fixes it by translating 0 to the real domain id for
> >> pvshim, but there may be a better way to do this.
> > 
> > My primary observation with the patch is that it presumably won't build for
> > other than x86. There are also indentation and other style issues, no S-o-b,
> > and no description. But I wonder whether a different approach doesn't want
> > taking: Wouldn't it help if max_init_domid was 1 in the shim case, with no
> > need for any other changes?
> > 
> > Also Cc-ing Michal as the author of the (possibly) offending patch.
> What if we set max_init_domid in pvshim case to the value returned by 
> get_initial_domain_id()
> in create_dom0()? The drawback is that we would waste some time in a loop if 
> the value is large.

I considered this too, but max_init_domid is a constant on x86; it looked
like a more intrusive change.

-- 
Manuel Bouyer <bouyer@xxxxxxxxxxxxxxx>
     NetBSD: 26 ans d'experience feront toujours la difference
--