Xbox vesa-like framebuffer

[Robert Millan <rmh@aybabtu.com>]

It seems the Xbox (hacked) firmware, Cromwell, sets up a vesa-like framebuffer
with predefined 640x480x32 RGBX settings at addr *(0xfd600800) [1]

I just gave a quick look at vbe.c to see how hard would it be to adapt it to
use default settings rather than BIOS calls.  Can someone provide a bit of
advice on what those settings would be?  In particular, I wonder about:

  `mode' (as returned by grub_vbe_get_video_mode_info())
  `active_mode_info.memory_model' (and in case of GRUB_VBE_MEMORY_MODEL_PACKED_PIXEL,
  do we have to setup vga palette?)
  `framebuffer.bytes_per_scan_line'
  `framebuffer.bytes_per_pixel'  --> 4, right?

Anything else I could have missed ?  Also, is there an easy way to get debugging
output printed somewhere (before we have to care about font stuff) in the form
of raw pixels ?  This thing doesn't seem to have a serial port or any other
simple debugging interface.

[1] from http://www.xbox-linux.org/wiki/Porting_an_Operating_System_to_the_Xbox_HOWTO#Video_Driver

-- 
Robert Millan

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<DRM> What use is a phone call, if you are unable to speak?
(as seen on /.)