Arch Linux

rochus

Member

Registered: 2007-02-14

Posts: 96

[SOLVED] resolution for 5.11, kernel mode setting, xf86-video-intel

Hi all,

I updated my arch installation on a Thinkpad T450s yesterday, which brought along kernel 5.11. After a reboot, the resolution during boot was smaller than before, I guess either 640x480 or 800x600 (don't really remember, sorry). Moreover, Xorg also started with that lower resolution. Interestingly, xrandr still listed all possible resolution for the screen, and manually invoking `xrandr --output eDP1 --auto` switched to the full resolution of 1920x1080. The system was running with xf86-video-intel, because the T450s is equipped with an additional Nvidia GPU, and the closed-source driver was the only supported one for GPU offloading some while back. However, there was no update to the intel driver. If needed, I can give you a list of each package which was updated. Removing the closed source driver solved at least the problem of Xorg starting with the wrong resolution - however, the resolution during boot is still not back to the full resolution of the display and remains at the 640x480 one.

Now I wonder...
1) ...why kernel mode setting doesn't use the full resolution, as it used to, under kernel 5.11. Am I simply missing some argument to the kernel? If yes, why did it work without it before?
2) ...if there's a problem with xf86-video-intel and the 5.11 kernel which leads to the wrong resolution? Or maybe is this an "inherited" problem due to the wrong resolution during boot?
3) ...if the closed source intel driver is actually still required for GPU offloading, as it was some long time ago, and which was the reason why I used it in the first place.

Would be happy if anyone could answer one or the other question above. In the past, the closed source driver gave me less issues than the open source driver, but I'm willing to use the open source driver as long as performance and energy consumption are comparable. I honestly didn't recently follow up on the development of the modesetting and closed source drivers anymore, and don't know about the drawbacks or benefits of either.

Cheers

PS: I probably added this post to the wrong board section. Feel free to move it to the Kernel section...

Last edited by rochus (2021-03-04 06:53:23)

V1del

Forum Moderator

Registered: 2012-10-16

Posts: 25,230

Re: [SOLVED] resolution for 5.11, kernel mode setting, xf86-video-intel

1. on some setups mode setting can be late to start and will initialize "after" xorg has already started which can lead to issues like you're describing in which case you will want to setup https://wiki.archlinux.org/index.php/Ke … _KMS_start (... potentially for both i915 and nvidia and nvidia_drm)

2. xf86-video-intel is in general in maintenance limbo and it doesn't really see any meaningful updates, it has often ran into issues in the past and is generally only recommended for iGPUs older than can do OGL2 (~2007 and earlier), modesetting is more actively maintained in comparison, and if it's any reference Ubuntu and Fedora do not ship xf86-video-intel on their installers for newer GPUs

3. That was never the case, offloading has always been supported by the modesetting driver (it's the other way around, support with xf86-video-intel was just added recently) the intel driver is also not closed source, but a different way of telling the system how to setup screen dimensions and draw xorg primitives.

But instead of throwing random guesses around maybe post a xorg.log and a

sudo journalctl -b

so we have some hard data on what's going on.

Mod note: Moving to Kernel & Hardware

rochus

Member

Registered: 2007-02-14

Posts: 96

Re: [SOLVED] resolution for 5.11, kernel mode setting, xf86-video-intel

Thanks for the clarification about the drivers! It appears I had some wrong knowledge and/or memory on what's what about them.

In any case, you can find the logs on ix.io: journalctl -b, Xorg log for xf86-video-intel, Xorg log for modesetting driver.

I'll give the early KMS start a try to fix the wrong resolution during boot as soon as I have time, and report back about success or failure. In any case, I'll stick to the modesetting driver for now.

Last edited by rochus (2021-03-03 08:38:02)

rochus

Member

Registered: 2007-02-14

Posts: 96

Re: [SOLVED] resolution for 5.11, kernel mode setting, xf86-video-intel

Thanks again, V1del. The Early KMS Start solved the issue with the wrong resolution during boot. Still interesting that this wasn't required pre-5.11. Anyway, I'll mark this thread as solved.