Re: [Xen-devel] Xen 4.3 development update

[Ian Campbell <Ian.Campbell@xxxxxxxxxx>]

On Mon, 2013-05-13 at 16:39 +0100, Anthony PERARD wrote:
> On 13/05/13 16:15, Ian Campbell wrote:
> > On Mon, 2013-05-13 at 16:08 +0100, George Dunlap wrote:
> >> OK -- so you're saying that qxl actually *does* work, but just in a 
> >> limited fashion: as long as the guest only access the standard vga 
> >> interface, then you can connect over spice; but if the guest uses the 
> >> special qxl interface, then it crashes.
> 
> Of what I can understand of the few tests I've run, and what it said in
> this thread, qxl *does not* work. The standard vga is, IMHO, for
> compatibility with a guest that does not have qxl driver or early at
> boot when a qxl driver can not be started.
> 
> QXL is not require in order to use SPICE. So there is no benefit for now
> of having "vga = qxl" in the guest config file.

So qxl working in "standard vga" mode is basically equivalent to
emulating the VGA, e.g. vga = "stdvga" in the guest config?

> >> We don't really use qxl, so that wasn't clear at first; we thought that 
> >> you were saying it didn't work at all.
> > 
> > yes, it's all much clearer to me now, thanks Fabio.
> > 
> >> If it didn't work at all, then there's no point exposing functionality 
> >> that can't actually work.  But since there is new functionality (albeit 
> >> limited) exposed by the "qxl" option, we should keep it in.
> >>
> >> But we do need to make sure to set people's expectations properly -- our 
> >> release notes will have to advertize "partial qxl support".
> > 
> > Fabio, Is there some mechanism by which we can disable the magic qxl
> > interface and only leave qxl vga enabled, i.e. to workaround the
> > unfortunate crash?
> 
> I believe we would have to remove "vga = qxl" somehow, like adding an
> error "QXL not supported for now", unless we are able to find the issue
> between Xen and QXL.

IMHO if it doesn't work or is not doing anything useful we should just
remove it from the API for 4.3, otherwise we'll just have to have
#define LIBXL_REALLY_HAS_QXL_THIS_TIME when it does work...

Ian.


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