I have a bootable debian CD in hand (from debian-cd.com), and an old rev A iMac that refuses to boot it. The CD boots up on my G4 without fail, but with this iMac it cannot boot. (open firmware says that it has trouble reading block 0). The iMac won't even mount the CD on the desktop in MacOS, and offers to format it for me. :-/
This machine has never had trouble reading/mounting any other CDs in its history, and this same disk works fine in every machine I've tried -- so I'm at a loss. Plan B: do a tftp-style net boot from open firmware. I've heard rumorsr that some OF implementations can do this, but I can't find any documentation on what the incantation might be at the OF prompt. Has anybody accomplished something liket this? I'd love some pointers.