Asahi not resizing to screen resolution

[datajournalist12]

I am brand new to Linux, and just installed Asahi Linux (which is based on Arch) on my M1 Mac Mini. My screen (an LG 49WL95C-WE) is an ultra-wide 5120x1440 (aspect ratio 32:9). I've run pacman -Syu to ensure everything is up to date.

My problem is that the system is treating my screen like a 1920x1080 display. When I go into Display Configuration under System Settings it indicates that this "is the only resolution supported by this display."

After some research, I tried setting a custom resolution:

$ cvt 5120 1440 60
# 5120x1440 59.96 Hz (CVT) hsync: 89.52 kHz; pclk: 624.50 MHz
Modeline "5120x1440_60.00"  624.50  5120 5496 6048 6976  1440 1443 1453 1493 -hsync +vsync

$ sudo xrandr --newmode "5120x1440_60.00"  624.50  5120 5496 6048 6976  1440 1443 1453 1493 -hsync +vsync

$ xrandr | grep -e " connected [^(]" | sed -e "s/\([A-Z0-9]\+\) connected.*/\1/"
None-1

$ sudo xrandr --addmode None-1 5120x1440_60.00

When I do this, the resolution now shows up as an option in Display Configuration. However, when I select it, the following vague error message appears: "Outputs could not be saved due to error."

I also tried the above steps with a 3840x1080 resolution. With this setting there is no error message. The screen flashes once, but there is no change in the aspect ratio.

Any help would be much appreciated as my system is unusable at the the current resolution.

[jannau]

There is no display processor driver (part of what on a PC would be called GPU) for linux yet. There is a single framebuffer which gets initialized at boot time. The interface to the display processor available at boot time offers not enough information which resolution the the display supports. The bootloader uses thus a heuristic which is biased to 1920x1080 displays. See AsahiLinux/m1n1#159 for a way around that.

5120x1440 will require further changes (same problemm as 4k mentioned in ticket) but 3840x1080 could work.

[datajournalist12]

@jannau I am happy to report that the solution suggested in the linked thread by @marcan (installation of boot_display-test.bin) worked at 3840x1080. I may not be getting the maximum possible resolution, but it still looks really good on my screen.

As thanks for y'all's hard work, I've signed up as a monthly contributor to the project.