Some early bootloader information from Raspberry Pi foundation...

Setting up the boot partition

partition 1 -- FAT32, bootable flag, type 'c'
partition 2 -- os, whatever

The boot partition must contain the following files,
get them from one of the official images:

* bootcode.bin : 2nd stage bootloader, starts with SDRAM disabled
* loader.bin : 3rd stage bootloader, starts with SDRAM enabled
* start.elf: The GPU binary firmware image, provided by the foundation.
* kernel.img: The OS kernel to load on the ARM processor.
  Normally this is Linux - see instructions for compiling a kernel.
* cmdline.txt: Parameters passed to the kernel on boot.

Optional files:
* config.txt: A configuration file read by the GPU.
  Use this to override set the video mode, alter system clock speeds,
  voltages, etc.
* vlls directory: Additional GPU code, e.g. extra codecs.
  Not present in the initial release.

Additional GPU firmware images, rename over start.elf to use them:
* arm128_start.elf : 128M ARM, 128M GPU split
  - use this for heavy 3D work, possibly also required for some video decoding)
* arm192_start.elf : 192M ARM, 64M GPU split
  - this is the default
* arm224_start.elf : 224M ARM, 32M GPU split
  - (use this for Linux only with no 3D or video processing.
    Its enough for the 1080p framebuffer, but not much else)