Now that I've booted my very first XO-1.75 kernel (still buggy, very early days), I can answer this question: it is because you use "initrd.arm.2" as the filename. OLPC's OpenFirmware doesn't support vfat due to patent reasons, it only support FAT (with 8.3 filename convention). If you rename "initrd.arm.2" to "initrd.2" (or anything that meets 8.3 filename convention, and fix the olpc.fth accordingly), it will work with vfat (at least, in my case it allows me to complete the boot process to console).mavrothal wrote: (will not work with vfat formatted media) and boot your XO-4 or XO-1.75.
cheers!