Bug#1025213: gnome-shell: Flickering and mangled screens on wayland if dri driver not available

[Fabio Pedretti]

This was fixed in mutter 43.8 and 44.4 as per mutter report
https://gitlab.gnome.org/GNOME/mutter/-/issues/2602

Bug#1025213: Mutter issue upstream 2602

[Gert van de Kraats]

Sorry, previous message has wrong link.

Mutter issue upstream opened 
athttps://gitlab.gnome.org/GNOME/mutter/-/issues/2602 .

Bug#1025213: Issue upstream

[Gert van de Kraats]

https://bugs.debian.org/cgi-bin/bugreport.cgi?bug=1025213
<https://bugs.debian.org/cgi-bin/bugreport.cgi?bug=1025213>

Bug#1025213: Mutter mr 2241

[Gert van de Kraats]

Problem is caused by mutter merge-request 2241:
https://gitlab.gnome.org/GNOME/mutter/-/merge_requests/2241 .

Shadow buffer is only used at software rendering.
Damage history is needed at copy from shadow buffer to onscreen,
to synchronize buffers.
I will open an issue upstream.
"

Bug#1025213: Extra info

[Gert van de Kraats]

I also tried mutter 43.2-4 without the Debian patches,
specially the Support-Dynamic-triple-double-buffering.patch .
This did not solve the problem,
The only difference is that during blinking of the cursor
there is switching between 2 different (old) backgrounds i.s.o. 3.

Bug#1025213: mutter

[Gert van de Kraats]

Thank you for adding gallium i915 to mesa 22.3.2-1. Now at least the
default Debian testing release is usable at my laptop.

But the  problem stills persists, if the i915-driver is removed and
kms_swrast is used.

In fact it is a mutter-problem (43.2-4) with shadow buffering.
Problem can be best viewed by opening a Terminal-window at main
Gnome-Shell window.
After some fast flickering the screen is updated every second which is
driven by the blinking of the cursor at the terminal.
Clearly can be seen the current terminal-line is correctly updated with
blinking cursor, but with 3 different old backgrounds.
If the next minute is started the time at the top is switching between 
previous and current time.


With environment variables MUTTER_DEBUG=kms and COGL_DEBUG=clipping this
can be monitored.

The syslog shows messages
gnome-shell[6588]: Device '/dev/dri/card0' prefers shadow buffer
gnome-shell[6588]: Initialized single buffered shadow fb for VGA-1
gnome-shell[6588]: Initialized single buffered shadow fb for LVDS-1

Shadow buffering is only used at software rendering!
The problem disappears if shadow buffering is disabled at
src/backends/native/meta-kms-impl-device.c at
function should_force_shadow_fb:
return FALSE;

Function drmGetCap is called by mutter to check if the device
prefers shadow buffering.

Bug#1025213: gnome-shell: Flickering and mangled screens on wayland if dri driver not available

[Fabio Pedretti]

Hi Gert and others,

mesa Debian package 22.3.0-3 added again i915 gallium driver.

Can you try again with mesa 22.3.1-1, which is in testing now, and report back?

Thanks.

Bug#1025213: Extra info

[Gert van de Kraats]

I installed  all mesa-packages of previous installed version 22.2.0-1.
I also installed previous installed kernel 5.19.11-1.
With these versions the problem still existed.

Bug#1025213: gnome-shell: Flickering and mangled screens on wayland if dri driver not available

[Simon McVittie]

Control: reassign -1 src:mesa 22.2.4-1
Control: severity -1 normal

>From what you've said about the various different drivers in use in
different modes, this looks like a Mesa issue more than a gnome-shell
issue, so I'm reassigning this. It also seems to be hardware-specific
and has a straightforward workaround (using gnome-shell in Xorg mode),
so I'm setting the severity accordingly (Mesa maintainers: this is a
guess, please increase or decrease as you wish).

This is certainly not a Debian Policy section 3.8 violation, because
Policy §3.8 refers to a specific technical feature, the "Essential: yes"
field, and gnome-shell is not an "Essential: yes" package.

On Thu, 01 Dec 2022 at 15:46:07 +0100, Gert van de Kraats wrote:
> my 32-bit Dell-laptop

There are many 32-bit Dell laptops in the world. Which model is this
and which CPU and GPU does it have? Please try running

reportbug --template libgl1-mesa-dri

and send the result to the bug address 1025...@bugs.debian.org so that
the Mesa maintainers have the necessary context.

smcv

Bug#1025213: DRM platform with kms_swrast

[Simon McVittie]

On Fri, 16 Dec 2022 at 22:40:28 +0100, Gert van de Kraats wrote:
> If the i915 dri driver is present gnome-shell is using the DRM platform
> (not the Wayland platform?) with this driver.

This is expected. gnome-shell acts as the Wayland compositor (the X11
equivalent would be Xorg, window manager and compositing manager all
in one process), so it can't use Wayland itself, for the same reasons
that Xorg can't output via X11. It has to use something lower-level
to talk directly to the kernel, and the DRM platform is exactly that
lower-level thing.

Ordinary applications running under GNOME (when it's in Wayland mode)
will use the Wayland platform as you'd expect, it's only gnome-shell
itself that can't.

Similarly, if there is no suitable hardware-specific DRI driver available
for your hardware, it's normal and expected that gnome-shell will use
the DRM platform with some sort of software-rendering driver.

smcv

Bug#1025213: DRM platform with kms_swrast

[Gert van de Kraats]

If the i915 dri driver is present gnome-shell is using the DRM platform
(not the Wayland platform?) with this driver.
If i915 is not present gnome-shell uses the DRM platform with the
kms_swrast-driver!
I did not see this with the lsof-command, because the name of the 
"zink"-driver was
shown which is hard-linked to the other dri-drivers and was opened and 
checked

unsuccessfully before the "kms_swrast" driver.

I tried an old version 22.0.5-1 of kms_swrast driver, but that did not help.
I will open an issue upstream.

Bug#1025213: i915g

[Gert van de Kraats]

The Gallium dri driver i915 22.3.0 also at my laptop is working and
stops the flickering problem.
Unfortunately it still is not supported and also has issues.
Specially with shaders it is not compatible with classic i915.
Less shaders are compiled without errors and also there is no fallback
(which works at classic i915 but can be very slow).
See https://gitlab.freedesktop.org/mesa/mesa/-/issues/5417.

Bug#1025213:

[wh]

I was able to build a copy of the libgl1-mesa-dri with the Gallium i915
driver enabled, and that fixed the flickering problem on my netbook from
that era.

Here's a copy if anyone would like to try
https://github.com/wh0/debian-mesa-i915g/releases/tag/22.3.0-1-1

I saw that Fedora had enabled it too:
https://bugzilla.redhat.com/show_bug.cgi?id=2100212

Bug#1025213: Extra info

[Gert van de Kraats]

I tried to install gnome-shell-common gnome-shell and
gnome-shell-extension-prefs 43.0.2.
This did not succeed because of failing login  (protocol)?

Then I compiled source gnome-shell 43.0.2 and installed at /usr/local...
I verified the version with gnome-shell --version.

This downgrade did not change anything. So gnome-shell itself is not the 
problem.


Subframes seem to be rendered OK, but old, already deleted subframes are 
repeatedly shown.

Do not know how to investigate further.
Upstream??

Bug#1025213: gnome-shell: Flickering and mangled screens on wayland if dri driver not available

[Gert van de Kraats]

Hello Simon,

Unfortunately my 32-bit Dell-laptop does not crash and I think the 
software-boys should not stop delivery of


software for older hardware, forcing to waste good working hardware.

Therefore I will use Debian testing as long as it supports 32-bit, so at 
least some one is testing something at 32-bit.


My previous upgrade was 2022-11-06, the next failing upgrade was 2022-11-27.

It contains 921 packages; also upgrade libgl1-mesa-dri:i386 22.2.0-1 
22.2.4-1 .


I am not sure problem is at gnome-shell itself.

I am almost sure it is not at mesa/swrast. I ran lsof for gnome-shell to 
check the open files.


If the i915 driver is present at X and wayland the i915 shared library 
is shown.


If the driver is not present at X the swrast library is shown, but not 
at wayland.


Perhaps gtk/pango is used for software-rendering at wayland.

I will try to downgrade gnome-shell and dependent packages.

Bug#1025213: gnome-shell: Flickering and mangled screens on wayland if dri driver not available

[Simon McVittie]

On Thu, 01 Dec 2022 at 01:11:15 +0100, Gert van de Kraats wrote:
> Recently a general upgrade was executed with gnome-shell
> upgrading from version 43.0-2 to 43.1-2.

Are you sure that the root cause was this gnome-shell upgrade, and not
an upgrade of the mesa packages that may have happened at the same time?

Does downgrading gnome-shell (and the mutter library that it depends on)
back to 43.0 resolve this? If not, then it is likely that there is no
gnome-shell change that will fix it.

Alternatively, does downgrading the Mesa packages (libgl1-mesa-dri and
related packages) to the version from Debian 11 (20.3.5-1) resolve this?

> Some user-friendly person has decided to stop support for the i915 dri
> driver.
> As a "service" the mesa-upgrade at Debian also automatically deletes this
> driver.

The old i915 driver was removed from the main mesa packaging and is now
in a separate driver collection, mesa-amber, consisting of drivers for
older hardware that are no longer actively maintained. The Mesa team
packaged mesa-amber () and it was in
the NEW queue for a while, but it seems to have disappeared. I'm not
sure what its status was, perhaps the archive administrators rejected it?

What CPU and GPU are you running this on? I see you're using an i686
kernel: is it a 32-bit system?

i686 (32-bit PC) systems are increasingly difficult to support or
test on, so it is looking as though Debian 12 is likely to be the last
version that can be installed on i686 hardware. It might be safer to
stick to Debian 11 on hardware this old, or upgrade to newer hardware
(second-hand 64-bit PCs are widely available, and any good-quality laptop
from the last 10 years would probably improve both performance and power
consumption compared with a 32-bit system, especially if it is a desktop).

If your GPU is old enough to be unsupported by the crocus and iris drivers
(which are the replacement for i915 for newer Intel GPUs), then your CPU
is probably also rather old, which can cause problems for the llvmpipe
(swrast) driver: that driver does some basic rendering on the CPU, but
to do that at an acceptable speed, it tries to make use of non-baseline
CPU extensions.

> Also if "Gnome on Xorg" is started there is no flickering problem.
> In that case swrast is used for software rendering.

If your GPU is too old for the drivers available in mesa, and the mesa-amber
drivers are not installed, then the intended fallback is llvmpipe
(swrast_dri.so). I would have expected that it would be used for both Xorg
and Wayland. However, GNOME in Wayland mode might have higher requirements
for the quality of the drivers than GNOME in Xorg mode, or just different
behaviour, resulting in flickering in Wayland mode but not in Xorg mode.

> I do not know which method gnome with wayland is using, but it is not
> swrast.

Do you have evidence that it is not using swrast? If yes, what?

smcv

Bug#1025213: gnome-shell: Flickering and mangled screens on wayland if dri driver not available

[Gert van de Kraats]

Package: gnome-shell
Version: 43.1-2
Severity: serious
Justification: Policy 3.8

Dear Maintainer,

Recently a general upgrade was executed with gnome-shell
upgrading from version 43.0-2 to 43.1-2.

After this upgrade the gnome-shell wayland screen is flickering
and mangled at any action. Flickering stops after short time,
but screen often is mangled.
During flickering different old or background screens are shown.
Also the logon-screen is flickering and mangled.

Some user-friendly person has decided to stop support for the i915 dri 
driver.

As a "service" the mesa-upgrade at Debian also automatically deletes this
driver.

If an old i915-dri driver is moved to the original location,
the flickering problem is gone.
Also if "Gnome on Xorg" is started there is no flickering problem.
In that case swrast is used for software rendering.
I do not know which method gnome with wayland is using, but it is not 
swrast.



-- System Information:
Debian Release: bookworm/sid
  APT prefers testing
  APT policy: (500, 'testing')
Architecture: i386 (i686)

Kernel: Linux 6.0.0-4-686-pae (SMP w/2 CPU threads; PREEMPT)
Locale: LANG=en_US.UTF-8, LC_CTYPE=en_US.UTF-8 (charmap=UTF-8), 
LANGUAGE=en_US:en

Shell: /bin/sh linked to /usr/bin/dash
Init: systemd (via /run/systemd/system)
LSM: AppArmor: enabled

Versions of packages gnome-shell depends on:
ii  dconf-gsettings-backend [gsettings-backend]  0.40.0-3
ii  gir1.2-accountsservice-1.0   22.08.8-1+b1
ii  gir1.2-adw-1 1.2.0-1
ii  gir1.2-atk-1.0   2.46.0-4
ii  gir1.2-atspi-2.0 2.46.0-4
ii  gir1.2-freedesktop   1.74.0-2
ii  gir1.2-gcr-3 3.41.1-1+b1
ii  gir1.2-gdesktopenums-3.0 43.0-1
ii  gir1.2-gdkpixbuf-2.0 2.42.10+dfsg-1
ii  gir1.2-gdm-1.0   43.0-1
ii  gir1.2-geoclue-2.0   2.6.0-2
ii  gir1.2-glib-2.0  1.74.0-2
ii  gir1.2-gnomebluetooth-3.0    42.4-1
ii  gir1.2-gnomedesktop-3.0  43-2
ii  gir1.2-graphene-1.0  1.10.8-1
ii  gir1.2-gstreamer-1.0 1.20.4-1
ii  gir1.2-gtk-3.0   3.24.35-1
ii  gir1.2-gtk-4.0   4.8.2+ds-3
ii  gir1.2-gweather-4.0  4.2.0-1
ii  gir1.2-ibus-1.0  1.5.27-4
ii  gir1.2-mutter-11 43.0-2
ii  gir1.2-nm-1.0    1.40.4-1
ii  gir1.2-nma-1.0   1.10.4-2
ii  gir1.2-pango-1.0 1.50.10+ds-1
ii  gir1.2-polkit-1.0    122-1
ii  gir1.2-rsvg-2.0  2.54.5+dfsg-1
ii  gir1.2-soup-3.0  3.2.1-2
ii  gir1.2-upowerglib-1.0    0.99.20-1+b1
ii  gir1.2-webkit2-4.1   2.38.2-1+b1
ii  gnome-backgrounds    43-1
ii  gnome-settings-daemon    43.0-3
ii  gnome-shell-common   43.1-2
ii  gsettings-desktop-schemas    43.0-1
ii  gstreamer1.0-pipewire    0.3.61-1
ii  libatk-bridge2.0-0   2.46.0-4
ii  libatk1.0-0  2.46.0-4
ii  libc6    2.36-5
ii  libcairo2    1.16.0-6
ii  libecal-2.0-2    3.46.1-1+b2
ii  libedataserver-1.2-27    3.46.1-1+b2
ii  libgcr-base-3-1  3.41.1-1+b1
ii  libgdk-pixbuf-2.0-0  2.42.10+dfsg-1
ii  libgirepository-1.0-1    1.74.0-2
ii  libgjs0g 1.74.1-1
ii  libgles2 1.5.0-1
ii  libglib2.0-0 2.74.1-2
ii  libglib2.0-bin   2.74.1-2
ii  libgnome-autoar-0-0  0.4.3-1
ii  libgnome-desktop-3-20    43-2
ii  libgraphene-1.0-0    1.10.8-1
ii  libgtk-3-0   3.24.35-1
ii  libgtk-4-1   4.8.2+ds-3
ii  libical3 3.0.16-1+b1
ii  libjson-glib-1.0-0   1.6.6-1
ii  libmutter-11-0   43.0-2
ii  libnm0   1.40.4-1
ii  libpango-1.0-0   1.50.10+ds-1
ii  libpangocairo-1.0-0  1.50.10+ds-1
ii  libpolkit-agent-1-0  122-1
ii  libpolkit-gobject-1-0    122-1
ii  libpulse-mainloop-glib0  16.1+dfsg1-2+b1
ii  libpulse0    16.1+dfsg1-2+b1
ii  libsecret-1-0