I've got a 4K laptop screen connected to a Dell 5K monitor. The Dell uses two Display Ports, and presents as 2 monitors; one with resolution up to 4K, and another with resolutions of 848x480 and 2560x2880. They way to get 5K on the external monitor seems to be to run both of its ports at the 2560 resolution. However, if I try to use xrandr to set those values, it tells me that the required resolution is greater than the max. The output from xrandr is given below. Is there a way I can raise the maximum from 8192 to something larger?
Screen 0: minimum 320 x 200, current 7680 x 2160, maximum 8192 x 8192
eDP-1 connected primary 3840x2160+3840+0 (normal left inverted right x axis y axis) 346mm x 194mm
3840x2160 60.00*+
2048x1536 60.00
1920x1440 60.00
1856x1392 60.01
1792x1344 60.01
1920x1200 59.95
1920x1080 59.93
1600x1200 60.00
1680x1050 59.95 59.88
1600x1024 60.17
1400x1050 59.98
1280x1024 60.02
1440x900 59.89
1280x960 60.00
1360x768 59.80 59.96
1152x864 60.00
1024x768 60.04 60.00
960x720 60.00
928x696 60.05
896x672 60.01
960x600 60.00
960x540 59.99
800x600 60.00 60.32 56.25
840x525 60.01 59.88
800x512 60.17
700x525 59.98
640x512 60.02
720x450 59.89
640x480 60.00 59.94
680x384 59.80 59.96
576x432 60.06
512x384 60.00
400x300 60.32 56.34
320x240 60.05
DP-1 connected 3840x2160+0+0 (normal left inverted right x axis y axis) 597mm x 336mm
3840x2160 60.00*+ 60.00
2560x1440 59.95 +
2560x2880 59.98 29.99
1920x1200 59.88
1920x1080 60.00
1600x1200 60.00
1680x1050 59.95
1280x1024 60.02
1280x800 59.81
1024x768 60.00
800x600 60.32
640x480 60.00 59.94
HDMI-1 disconnected (normal left inverted right x axis y axis)
DP-2 connected (normal left inverted right x axis y axis)
848x480 59.74 +
2560x2880 59.98 29.99
HDMI-2 disconnected (normal left inverted right x axis y axis)
--fb
flag for that, likexrandr --fb 16384x16384
but thats as the name says the framebuffer not the real resolution which you would need to set seperatly.