How to use /dev/fb0 as a console from userspace, or output text to it

Question

So I have a Palm Pre (original P100EWW) model that I enabled developer mode on, and installed a Debian Squeeze chroot. Works great. I have plans to use this for ANYTHING (bittorrent peer, web server) but a phone.

I noticed if I do a cat /dev/urandom > /dev/fb0 it actually writes random pixels to the screen until a No space left on device error is generated. Awesome, now I can use the display.

So what kind of utilites are there that will either A) let me use /dev/fb0 as a console I can output text to or B) render text on /dev/fb0 from the command line.

I don't know about recompiling the kernel for this yet (I'd love to eventually strip WebOS off entirely and turn this into a minimal ARM server) so userspace tools if they exist is what I'm asking about. Also would prefer to render directly to /dev/fb0 and not use X.

Answer 1

To use the framebuffer as console you need the fbdev module. You may have to recompile your kernel.

You may also be interested in the DirectFB project, which is a library that makes using the framebuffer easier. There are also applications and GUI environments written for it already.

Answer 2

For the console side, you can echo stuff to /dev/console or you can use syslog, and depending on various other settings, it may show up on the console.

For images, I just tried catting a bmp file to fb0 and it actually worked! (sortof - multiple copies, smaller size)

I found a bmp-to-framebuffer program here. That should be a perfect example of the format the fb0 is expecting. There is also fbi, a program for writing directly to the frame buffer.