XMir hangs in xf86OpenConsole() WAS: Re: Fwd: [Bug 1256116] Re: Documentation instructs to install the package unity-system-compositor, but this is not sufficient for having Mir

[Thomas Hellstrom]

Hi!

Please see below.

On 04/09/2014 10:11 AM, Christopher James Halse Rogers wrote:
> On Wed, Apr 9, 2014 at 5:44 PM, Thomas Hellstrom
> <thellstrom at vmware.com> wrote:
>> Hi!
>>
>> Thanks for the reply.
>> I've done a bit of debugging, and this happens because the unity-greeter
>> tries to create up a pixmap of size (0,0). X  doesn't allow that and
>> sends an error to unity-greeter that shuts down. Lightdm then shuts down
>> Mir and XMir and tries to start a new non-XMir X server and that's the
>> one that hangs. So the hang seems to be a symptom of a bug /
>> inconsistency in the lightdm error path.
>>
>> So why does unity-greeter (actually gtk::screen) think the screen is of
>> size (0,0)? I tried to dump the gtk <-> Xserver communication and it
>> appears like gtk queries the crtcs / outputs and gets (0,0) answers,
>> although X replies the root window is of size 800x600, so I need to
>> somehow make XMir respond with the correct modes on crtcs / outputs.
>> Reading the XMir code it appears like nothing really performs an initial
>> modeset, although an initial mode configuration is performed.
>>
>> Is the XMir-enabled DDX driver responsible for calling
>> xf86SetDesiredModes(), and in that case, where is a suitable place for
>> the driver to do that?
>
> Yeah, we currently expect XMir-enabled DDXen to call
> xf86SetDesiredModes themselves, at the same point as they'd normally
> call call it (and after xmir_mode_pre_init()).
>
> We could do it in the XMir module itself, but I was leary of side
> effects the DDXen weren't expecting

OK. That made XMir work again.

Is this a new requirement or was that present also with Ubuntu 13.10?

In any case, while window movement and 3D looks as snappy as in 13.10
there is a 0.5 second or so latency when I type text in
terminal windows. Very annoying. Is that a known problem? I'll try to
find out whether this delay happens in XMir or in Mir.

Thanks,
Thomas