Bug#909770: gdm3: Does not show the list of users and fails to start any session

[Sergio Villar Senin]

O Ven, 28-09-2018 ás 12:47 +0100, Simon McVittie escribiu:
> On Fri, 28 Sep 2018 at 11:01:09 +0200, Sergio Villar Senin wrote:
> > O Xov, 27-09-2018 ás 22:39 +0100, Simon McVittie escribiu:
> > > On Thu, 27 Sep 2018 at 23:16:05 +0200, Sergio Villar Senin wrote:
> > > >    The background of the plyumouth theme is shown but the list
> > > > of
> > > >    users is not there as expected.
> 
> How many screens are you using, and how are they connected?  From
> your
> log it looks as though the answer might be one laptop internal panel,
> connected via eDP, and no external screens. Is that correct?

That's correct

> If you are using a plymouth theme that resembles the background you
> would
> expect for the gdm greeter (user list), please retry with a different
> plymouth theme such as softwave or lines and tell me what you see?
> (What
> I'm trying to determine here is whether the most recent pixels on
> your
> screen came from plymouth or gdm.)

I basically started without plyumouth enabled and the screen becomes
black with the cursor in the top left corner of the screen. At that
point I tried to attach an external screen, and guess what? then I
could see the VTs in F2,F3... and in F1 there was the gray background
(nothing else just that) from gdm.

> > I don't see anything specially wrong there except these lines:
> > 
> > laptop kernel: [drm:intel_dp_start_link_train [i915]] *ERROR*
> > [CONNECTOR:71:eDP-1] Link Training failed at link rate = 270000,
> > lane
> > count = 2
> 
> I agree. This looks more like a kernel bug than anything else - I'm
> not
> sure that this is anything that gdm3 can fix - but I'll try to get a
> bit more information about what does and doesn't work before
> reassigning.
> 
> If you follow the workaround that you described (involving
> suspend/resume),
> do you get a similar warning about link training after resuming?

After resuming everything seems to work fine and I haven't seen any
error in the journal.

> You said that lightdm works OK. Do you get similar warnings about
> link
> training when using lightdm?

Not a single one. The last warning appears just after the
"/usr/lib/gdm3/gdm-x-session[3172]: (II) modeset(0)" lines.

> If you edit /etc/gdm3/daemon.conf and edit it to have
> 
>     [daemon]
>     WaylandEnable=false
> 
> then go back to gdm, does that make it work?

No luck, same result.

BR