This patch fixes the RPX boot which was generating a bad boot image (it was an ELF) and will do the 'cp' command line correctly, too.
This patch also adds a boot image that will burn itself (and an initrd if present) to the flash on the RPX. It's large so I put it here: http://www2.fsmlabs.com/~cort/rpx.patch.gz ** Sent via the linuxppc-embedded mail list. See http://lists.linuxppc.org/