Bug#956121: Blank screen on 2nd display using wayland

[Simon McVittie]

On Tue, 07 Apr 2020 at 17:43:25 +0200, Pierre Cheynier wrote:
> When upgrading mutter from 3.34.3-1 to 3.34.4-1 (testing), my second
> screen (eDP / 3440x1440) is completely white, the second one show
> glitches and freezes during a few tens sec. probably while trying to
> sync the other one before aborting.

Is this reproducible by upgrading/downgrading only libmutter-5-0 and
closely-related packages, without altering anything else?

Are you able to test this with mutter and gnome-shell 3.36.x from
experimental? We're close to uploading those to unstable.

> HW setup: i915
> 
> $ lspci | grep VGA
> 00:02.0 VGA compatible controller: Intel Corporation 3rd Gen Core
> processor Graphics Controller (rev 09)
> 01:00.0 VGA compatible controller: NVIDIA Corporation GK107GLM [Quadro
> K2000M] (rev a1)

You appear to have a dual-GPU system. Is the NVIDIA device completely
disabled, or are they both active via some sort of dual-GPU arrangement
like Bumblebee?

Do you have the proprietary NVIDIA drivers installed? (I'm guessing you
don't, because reportbug would have told us about the non-free module.)

> Anything relevant that would help troubleshooting the issue?

systemd journal entries during GNOME Shell startup and around the time
you reproduce a bug are usually useful, particularly for hardware-related
things like this.

(Or during mutter startup and around the time you reproduce a bug, if
you are genuinely using the standalone mutter executable - which is not
really recommended, but should in principle work.)

Looking at the commits between 3.34.3 and 3.34.4,
"renderer-native: Fix memory leak in secondary GPU update" and
"kms-impl-simple: Handle mode set race conditions gracefully" look
potentially relevant as things that might have caused a regression,
but I'm just guessing really.

    smcv