Public bug reported:
I have a bog-standard loginctl multiseat setup, using lightdm because of
#2033323. Except for the lack of session locking, it worked beautifully,
across multiple reboots. Until it didn't.
Box woke from suspend, and to be fair was acting strangely even then
(Steam suddenly tried to launch using the iGPU), so suspend may well be
broken on this box, but if so, that's a separate issue. Anyway, I
rebooted, no lightdm greeter to be seen, the screen on seat1 was black.
I did not have easy access to seat0 at the time.
The journal has, looping:
systemd[1]: Failed to start Detect the available GPUs and deal with any system
changes.
systemd[1]: lightdm.service: Start request repeated too quickly.
token systemd[1]: lightdm.service: Failed with result 'exit-code'.
token systemd[1]: Failed to start Light Display Manager.
The first line is from gpu-manager.service, whose log contains
Vendor/Device Id: 1002:164e
BusID "PCI:110@0:0:0"
Is boot vga? no
Error: can't access /sys/bus/pci/devices/0000:6e:00.0/driver
The device is not bound to any driver.
Vendor/Device Id: 1002:73ff
BusID "PCI:3@0:0:0"
Is boot vga? yes
Error : Failed to open /dev/dri
Error : Failed to open /dev/dri
Error : Failed to open /dev/dri
Error : Failed to open /dev/dri
x-0 log has
vesa: Ignoring device with a bound kernel driver
vesa: Ignoring device with a bound kernel driver
(EE)
Fatal server error:
(EE) no screens found(EE)
Scary.
Thing is, both the iGPU and the dGPU are claimed by amdgpu, their
"driver" symlink is accessible just fine. Switch back to gdm via dpkg-
reconfigure, it boots up fine again. It's just lightdm that's hosed.
I tried purging lightdm and lightdm-gtk-greeter, along with and
/var/lib/lightdm, and reinstalling the packages, but no dice. What does
work is starting lightdm.service manually over ssh: It takes about 1-4
tries for both gpu-manager and lightdm to successfully launch and bring
up both greeters. Reboot, and it fails again.
Some kind of race condition due to too lax timing and/or dependencies in
the lightdm service file? Something unrelated changed the order and or
speed at which systemd executes the service files, i.e. it worked by
accident before and now it doesn't?
ProblemType: Bug
DistroRelease: Ubuntu 22.04
Package: lightdm 1.30.0-0ubuntu5
Uname: Linux 6.4.12-060412-generic x86_64
ApportVersion: 2.20.11-0ubuntu82.5
Architecture: amd64
CasperMD5CheckResult: pass
Date: Thu Aug 31 03:16:56 2023
InstallationDate: Installed on 2023-08-25 (5 days ago)
InstallationMedia: Ubuntu 22.04.3 LTS "Jammy Jellyfish" - Release amd64
(20230807.2)
SourcePackage: lightdm
UpgradeStatus: No upgrade log present (probably fresh install)
** Affects: lightdm (Ubuntu)
Importance: Undecided
Status: New
** Tags: amd64 apport-bug jammy third-party-packages
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https://bugs.launchpad.net/bugs/2033569
Title:
suddenly choked on multiseat config in a way that survives reboots and
even purging it
Status in lightdm package in Ubuntu:
New
Bug description:
I have a bog-standard loginctl multiseat setup, using lightdm because
of #2033323. Except for the lack of session locking, it worked
beautifully, across multiple reboots. Until it didn't.
Box woke from suspend, and to be fair was acting strangely even then
(Steam suddenly tried to launch using the iGPU), so suspend may well
be broken on this box, but if so, that's a separate issue. Anyway, I
rebooted, no lightdm greeter to be seen, the screen on seat1 was
black. I did not have easy access to seat0 at the time.
The journal has, looping:
systemd[1]: Failed to start Detect the available GPUs and deal with any
system changes.
systemd[1]: lightdm.service: Start request repeated too quickly.
token systemd[1]: lightdm.service: Failed with result 'exit-code'.
token systemd[1]: Failed to start Light Display Manager.
The first line is from gpu-manager.service, whose log contains
Vendor/Device Id: 1002:164e
BusID "PCI:110@0:0:0"
Is boot vga? no
Error: can't access /sys/bus/pci/devices/0000:6e:00.0/driver
The device is not bound to any driver.
Vendor/Device Id: 1002:73ff
BusID "PCI:3@0:0:0"
Is boot vga? yes
Error : Failed to open /dev/dri
Error : Failed to open /dev/dri
Error : Failed to open /dev/dri
Error : Failed to open /dev/dri
x-0 log has
vesa: Ignoring device with a bound kernel driver
vesa: Ignoring device with a bound kernel driver
(EE)
Fatal server error:
(EE) no screens found(EE)
Scary.
Thing is, both the iGPU and the dGPU are claimed by amdgpu, their
"driver" symlink is accessible just fine. Switch back to gdm via dpkg-
reconfigure, it boots up fine again. It's just lightdm that's hosed.
I tried purging lightdm and lightdm-gtk-greeter, along with and
/var/lib/lightdm, and reinstalling the packages, but no dice. What
does work is starting lightdm.service manually over ssh: It takes
about 1-4 tries for both gpu-manager and lightdm to successfully
launch and bring up both greeters. Reboot, and it fails again.
Some kind of race condition due to too lax timing and/or dependencies
in the lightdm service file? Something unrelated changed the order and
or speed at which systemd executes the service files, i.e. it worked
by accident before and now it doesn't?
ProblemType: Bug
DistroRelease: Ubuntu 22.04
Package: lightdm 1.30.0-0ubuntu5
Uname: Linux 6.4.12-060412-generic x86_64
ApportVersion: 2.20.11-0ubuntu82.5
Architecture: amd64
CasperMD5CheckResult: pass
Date: Thu Aug 31 03:16:56 2023
InstallationDate: Installed on 2023-08-25 (5 days ago)
InstallationMedia: Ubuntu 22.04.3 LTS "Jammy Jellyfish" - Release amd64
(20230807.2)
SourcePackage: lightdm
UpgradeStatus: No upgrade log present (probably fresh install)
To manage notifications about this bug go to:
https://bugs.launchpad.net/ubuntu/+source/lightdm/+bug/2033569/+subscriptions
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