** Also affects: ubuntu-drivers-common (Ubuntu)
Importance: Undecided
Status: New
** Changed in: ubuntu-drivers-common (Ubuntu)
Assignee: (unassigned) => jeremyszu (os369510)
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https://bugs.launchpad.net/bugs/1958488
Title:
[nvidia][xorg] display hangs on boot LOGO
Status in OEM Priority Project:
Confirmed
Status in gdm3 package in Ubuntu:
New
Status in ubuntu-drivers-common package in Ubuntu:
New
Bug description:
[Impact]
* In Ubuntu 20.04 (which using Xorg with proprietary nvidia driver), in some
cases, the nvidia driver will probe later than launching gdm.
* If above race condition happens in iGPU + nvidia cases and monitor
connects to dGPU, which will cause gdm starts with wayland as opposed to Xorg.
Which may lead the monitor stuck in black-screen or boot LOGO.
[Test Plan]
* The environment:
1. A desktop or workstation which containing an iGPU.
2. Plug a nvidia graphic card to the system and installing proprietary
nvidia driver (470 in my case)
3. Attach a monitor to dGPU and leave iGPU connect to nothing.
(in my test environment, there is the other ethernet card and TBT4 cards)
* Setup a cronjob,
e.g. @reboot /home/u/test.sh
* Have a test script in something like /home/u/test.sh as
#!/bin/bash
sleep 20
count="$(cat /home/ubuntu/count)"
count=$((count+1))
echo $count | tee /home/ubuntu/count
journalctl -b | grep -q -i wayland || sudo reboot
* the system will probably stuck in black-screen or boot LOGO.
* Before applying the fix, the fail rate is 6/24 (fail 6 time in 24 runs).
* After applying the fix, it got pass within 90 reboot cycles.
[Where problems could occur]
* The patch checkes device/boot_vga with tag "master-of-seat". If a system
without any GPU as boot_vga then it will wait 10 seconds in the loop.
* I tried to detach all monitors from the system and the boot_vga still
exist (default to use iGPU, the first device found during initialization)
* I don't think they will a case which boot_vga doesn't exist in this moment
because:
In drivers/gpu/vga/vgaarb.c (linux package)
vga_arb_select_default_device() has a fallback function to determine the
boot_vga device to prevent firmware doesn't pass correct efifb to linux-kernel.
---
Test environment/steps:
1. A desktop or workstation which containing an iGPU.
2. Plug a nvidia graphic card to the system and installing proprietary nvidia
driver (470 in my case)
3. Attach a monitor to dGPU and leave iGPU connect to nothing.
(in my test environment, there is the other ethernet card and TBT4 cards)
4. Reboot system.
Based on:
$ cat /lib/udev/rules.d/61-gdm.rules
# disable Wayland on Hi1710 chipsets
ATTR{vendor}=="0x19e5", ATTR{device}=="0x1711",
RUN+="/usr/lib/gdm3/gdm-disable-wayland"
# disable Wayland when using the proprietary nvidia driver
DRIVER=="nvidia", RUN+="/usr/lib/gdm3/gdm-disable-wayland"
It will disable wayland by default if proprietary nvidia driver load.
But in some race condition cases, the nvidia probe is later than gnome
launches. (The fail rate is 6/24.)
Thus, ubuntu-gdm has a fix for Bug#1794280 to add
"ExecStartPre=@libexecdir@/gdm-wait-for-drm".
The gdm-wait-for-drm is intend to make sure all drm udev devices
enumerated before launching gdm.
It rely on at least one "master-of-seat" graphic card for gdm but it's not
rigorous enough.
Since most of graphic cards are own "master-of-seat"[1].
In my case, it detects the iGPU is probed but dGPU.
However, the display is attached to dGPU.
We need to make sure the targeted gpu (connecting to monitor) is probe
before launching gdm.
debian bug: https://bugs.debian.org/cgi-bin/bugreport.cgi?bug=1004131
upstream bug: https://gitlab.gnome.org/GNOME/gdm/-/issues/763
[1] https://www.freedesktop.org/wiki/Software/systemd/multiseat/
/lib/udev/rules.d/71-seat.rules
/lib/udev/rules.d/71-nvidia.rules
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