Re: [Ltib] LTIB for Raspberry Pi

[Mike Goins]

> Someone asked about the Pi's bootloader situation.   My understanding is that 
> the GPU runs first when the board is powered up.  It looks for an executable 
> to load & run on the first (VFAT) partition on the SD card, and that this 
> executable is closed-source, provided by the Pi foundation (and/or Broadcom), 
> and does traditional boot-loader-y things, like set up memory (which is 
> shared between the GPU and the ARM CPU, I believe), and load a kernel.  I 
> suppose there's no reason we couldn't then run uBoot instead of a linux 
> kernel, but there seems little point.  There is no ROM part, so the device 
> must boot from the SD card.


We do something similar with a Freescale chip.  We a wrote a little
microcode program that is flashed into the eeprom on the processor.
It's just enough the get the processor to read the bootloader (in this
case u-boot) from the first partition of a microSD card.   The 2nd
partition contains the rootfs and kernel.  A modified u-boot (or
modified u-boot parameters tucked in the same partition) allows us to
use a tftp/nfs dev enviroment since pulling a card to image just takes
to long.  Production units get a hard-coded u-boot to do sdcard boot
sequence.

Seems there has been some work to get u-bbot working on RPi:
http://kernelnomicon.org/?p=127
https://github.com/gonzoua/u-boot-pi/tree/rpi

Apologies for wandering off-topic.  I've ordered an RPi this morning
and should have it in a few days.