[Shield Tablet Android Development] wertus33333:
Some ideas:

-Which kernel are you using? I posted one with some fixed stuff some posts ago.

-Also, starting from ubuntu 18 gdm is used instead of lightdm by default

-Enable autologin in gdm/gdm3 or/and lightdm, had many problems with gdm login which i could "solve" this way and forget until i was able to propperly set things in ubuntu-settings and copy the conf

-have a look at other logs in /var/log, your log tells you: "(==) Log file: "/var/log/Xorg.0.log", Time: Mon Nov 1 19:17:49 2021". The Xorg.#.log (there are other similar ones, you can delete the logs and restart to generate new ones) files are always giving a lot of information (which actually helped me fix touch in 18.04)

-In 18.04 init.rc scripts do not work propperly/at all so you have to convert them to system.d scripts (otherwise many things are broken). I posted my converted scripts some posts ago, just make sure to alter the paths, username and anything else specific to your device...

EDIT:

If you want the best possible experience for an ubuntu tablet use 16.04 with opengl 4.5 and vulkan drivers. If you cant find some application you need, you'll have to recompile them (preferably on the device) tho.

Already recompiled many retroarch cores, retroarch, dolphin emu, Mupen64... i can share this if you are interested. box86 and wine for simple x86 32bit windows applications is pretty nice too (worms works xD). Although setting it up took some time... Ended up using some raspberry pi tutorial. Also, 2 PS4 controllers (the new ones with the top light bar, old ones lag AF) at the same time work great and i am trying to get this (https://github.com/devmapal/nvidia-shield-controller-driver/) working so we could have the original 2015 shield controller working over wifi (without success, the commits to the kernel are on my git).

Emulation performance seems to be worse than on android (compared to youtube vids as i dont have android on the device anymore) probably due to bad optimization for linux and ubuntu 16:

-Dolphin: 5-12fps (super smash bros)

-mupen64: crashes

Retroarch:

-mupen64: just some color splashes around the screen, the game and sound run at full speed in the background (can even use controllers and "play" games blind)

-gb,gbc,gba: runs great

-nds: hearth gold/soul silver work, sound is a bit glitchy sometimes

-ppsspp: runs great upscaled to 3-4x original resolution depending on game

-dreamcast: works great, also upscaled to slightly less than full hd (power stone, crazy taxy)

Unfortunately the 32bit cpu holds us back a lot bcs (as far as i understand) most dynamic recompilers only exist for 64bit. A waste for the gpu...

Biggest limitation is ofc the locked nvidia flash mode, without the possibility of unrecoverably bricking the device by trying a new bootloader (there are MANY tegra k1 devices mainlined into the linux kernel by now but they all use uboot bootloader) it is very hard to build/develop something. found https://github.com/shchmue/Lockpick_RCM which generates the rcm key for tegra x1 (switch) SOC so i wondered if that could be possible or maybe with an spi flasher? unfortunately i have no idea about such things so help would be great.

If we can use a custom uboot bootloader we can use a modified version of the mainlined jetson kernel with nouveau driver and always update to the latest debian/ubuntu as long as it supports 32bit

If someone can help with any of this, help would be greatly appreciated.