OFW loads Linux from CaFe NAND FLASH / JFFS2

[Mitch Bradley]

I got the CaFe NAND FLASH driver and jffs2 reader integrated into Open 
Firmware.

OFW mounted the jffs2 filesystem (the build 91 image, with summary 
nodes) and loaded /boot/vmlinuz in just under 6 seconds.

That's using DMA access to the CaFe NAND controller.  Programmed I/O 
takes about twice as long.

OFW doesn't have support for writing individual files to jffs2, but it 
can copy verbatim filesystem images onto the NAND FLASH..  That's how I 
got jffs2 onto the FLASH; I copied the distribution image to an ordinary 
file on a USB key (right out of the box, with the factory FAT 
filesystem), and told OFW to splat that file onto the NAND FLASH.  The 
NAND copy methods knows about the factory bad block list and skip around 
the bad ones.

The JFFS2 file system reader code adds approximate 3400 bytes to OFW's 
ROM footprint.  It supports node processing  both with and without 
summaries, file reading with zlib decompression as necessary, path 
processing, symlinks, and directory listing.

The zlib decompressor size is not included in that footprint size, 
because it is already present in OFW for other reasons.

The CaFe NAND driver's ROM footprint is 1800 bytes.