Severe graphical slowdown and tearing after switching VTs

[strugee]

Qubes OS version

R4.0

Affected component(s) or functionality

dom0 Xorg

Brief summary

When I switch to either a different TTY or to LightDM running on a different VT (I have this situation because of light-locker), then switch back, Xorg is all messed up and doesn't draw stuff right.

To Reproduce

1. Switch to a VT with e.g. Ctrl-Alt-F4
2. Switch back to the original VT with Ctrl-Alt-F1(? I think my Xorg's running on VT1 but I don't want to check because then I'd trigger this bug and have to reboot which would be annoying)

Expected behavior

I switch back and everything reacts normally.

Actual behavior

Xorg dom0 drawing is super slow. For example, it takes 3+ seconds for the window switcher to show up when I hit Alt-Tab.

Screenshots

I can confirm that this screenshot accurately depicts what actually ended up on my monitor. Notice that I have both a top and bottom bar (the latter of which isn't being drawn at all), and that both windows do not have their borders driven. Mousing over the window list in the bottom bar, or over the qubes icon in the upper-left, or generally forcing anything to change such that it would need redrawing does make (only) that particular element show up.

Additional context

% cat /etc/modprobe.d/disable-nvidia.conf
blacklist nouveau
blacklist nvidia
blacklist nvidia-drm
blacklist nvidia-modeset
alias nouveau off
alias nvidia off
alias nvidia-drm off
alias nvidia-modeset off

% cat /proc/cmdline
root=/dev/mapper/qubes_dom0-root rd.luks.uuid=luks-86339b49-c303-4652-8393-90f75f4f1055 rd.lvm.lv=qubes_dom0/root rd.lvm.lv=qubes_dom0/swap i915.alpha_support=1 nouveau.modeset=0 rd.driver.blacklist=nouveau video=vesa:off rhgb quiet rd.qubes.hide_all_usb plymouth.ignore-serial-consoles systemd.log_level=debug systemd.log_target=kmsg log_buf_len=1M printk.devkmsg=on enforcing=0

My laptop (a System76 Oryx Pro, oryp4) has dual Intel/Nvidia graphics cards. I had to disable Nvidia in order to get the Qubes ISO to boot and have kept that setting ever since. I haven't tried enabling Nvidia again since enabling things like kernel-latest.

Logs:
hypervisor.log
Xorg.0.log
dmesg (sorry for the systemd spam... I think it might be left over from some debugging and if it's a big problem I can look into it)

Solutions you've tried

None. I will probably try booting kernel instead of kernel-latest when I get a chance, just in case that's related.

Relevant documentation you've consulted

https://www.qubes-os.org/doc/gui-configuration/, https://www.qubes-os.org/doc/intel-igfx-troubleshooting/ (this sounds similar and I do have the referenced Xorg log line, but it only happens when I switch to/from VTs), https://www.qubes-os.org/doc/nvidia-troubleshooting/

I also searched the mailing list.

Related, non-duplicate issues

https://github.com/QubesOS/qubes-issues/issues?utf8=%E2%9C%93&q=is%3Aissue+tty+flickering+is%3Aclosed+, https://github.com/QubesOS/qubes-issues/issues?q=is%3Aissue+switching+to+tty+is%3Aclosed

[na--]

@strugee, did you manage to fix or work around this issue?

[strugee]

No. I haven't poked at it since I filed this report though. Generally I just don't switch VTs.

[strugee]

This appears to have possibly gone away for me. I need to do some more testing, though.

[iamahuman]

Is this #5460? Then, does xorg-x11-drv-intel-v2.99.917-49.20210126 (QubesOS/updates-status#2328) solve it?

[github-actions]

This issue is being closed because:

• This issue is on the "Release 4.0 updates" milestone.
• Qubes OS 4.0 reached EOL (end-of-life) over one year ago.
• There has not been any activity on this issue in over one year.

If anyone believes that this issue should be reopened and reassigned to an active milestone, please leave a brief comment.
(For example, if a bug still affects Qubes OS 4.1, then the comment "Affects 4.1" will suffice.)