Re: [Xen-devel] [PATCH v2 25/24] xl: Document VGA problems arising from lack of physmap dmop

[Ross Lagerwall <ross.lagerwall@xxxxxxxxxx>]

On 10/06/2017 03:51 PM, Wei Liu wrote:
> On Fri, Oct 06, 2017 at 03:33:52PM +0100, Ian Jackson wrote:
> > [ extra patch, following test report from Ross ]
> >
> > Ross reports that stdvga guests do not work, and cirrus guests are
> > slow, because qemu tries to do xc_domain_add_to_physmap.  We will need
> > another dmop to fix this properly.
> >
> > For now, document the problem.
> >
> > Signed-off-by: Ian Jackson <Ian.Jackson@xxxxxxxxxxxxx>
> > Reported-by: Ross Lagerwall <ross.lagerwall@xxxxxxxxxx>
> > CC: Ross Lagerwall <ross.lagerwall@xxxxxxxxxx>
> > CC: Wei Liu <wei.liu2@xxxxxxxxxx>
> > CC: Paul Durrant <Paul.Durrant@xxxxxxxxxx>
> > ---
> >   docs/man/xl.cfg.pod.5.in | 6 ++++++
> >   1 file changed, 6 insertions(+)
> >
> > diff --git a/docs/man/xl.cfg.pod.5.in b/docs/man/xl.cfg.pod.5.in
> > index 8446d43..46b5ae6 100644
> > --- a/docs/man/xl.cfg.pod.5.in
> > +++ b/docs/man/xl.cfg.pod.5.in
> > @@ -2239,6 +2239,12 @@ For example, cdrom insert will fail.
> >   
> >   =item
> >   
> > +Domains with stdvga graphics cards to not work.
> > +Domains with cirrus vga do work,
> > +but there are performance problems with the vga console.
> > +
> I don't follow. Do you imply cirrus doesn't need add_to_physmap to
> function?
For both stdvga and cirrus, the function gets called and fails (although 
QEMU doesn't log an error by default). With stdvga the VM wedged. With 
cirrus, the VM worked but the display performance seemed worse than normal.
--
Ross Lagerwall

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