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Colin Macdonald edited this page Jan 14, 2014 · 12 revisions

/dev/graphics/fbX

I wasted a lot of time wondering why /dev/graphics/fb0 was 1280x33 (and trying to hack modelines, etc). Answer: its the black grab bar at the top of Android's GUI (with the clock, wifi indicator, etc). I had an xterm running in 1280x33 before I clued in!

On my Galaxy Note 8, fb3 is the correct framebuffer. Not sure what fb1 and fb2 are!

Meefik suggests "cat /dev/random > /dev/graphics/fb0". This is useful to see which ones are connected to something but it doesn't tell you what is what. I used trial-and-error.

Freeze Android UI

On my Galaxy Note 8, I have to use "Stop" for framebuffer to work. (TODO: maybe Pause, but "Don't Freeze" definitely doesn't work).

X Options: "Display" setting

In the same page where you can change which fbX to use, there is a setting "Display" (or similar, I don't have my device with me atm). This setting just changes the X11 display server (notably the "0" in /var/log/Xorg.0.log). So fiddling this setting is unlikely to make your framebuffer work!

My debugging workflow

After installing. I use the following workflow for debugging framebuffer. Maybe this will help someone else.

  1. Start LinuxDeploy and then start your distro.
  2. ssh in from my laptop.
  3. "killall X" (or maybe Xorg)
  4. modify /home/android/.xnitrc and /etc/X11/xorg.conf
  5. "xinit"
  6. ctrl-C to kill X, back to step 4, repeat.

All the while, in another ssh session, you can look at /var/log/Xorg.0.log

I also did "sudo -i", "chmod 666 /etc/X11/xorg.conf" so that I could edit that file as user android. The xorg.conf can get overwritten/edited by Linux Deploy (maybe the "Reconfigure" button?). Keep a backup if you edit it.

TODO: Possibly removing the "# linux deploy" comments (e.g., from /dev/graphics/fb0) will prevent it from modifying them?

http://your_computer:3142/XXXX where XXXX is one of armdebian, armubuntu, or armkali

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