-drive if=virtio,id=sys,file=/path/to/disk.img -cdrom /path/to/install.iso -boot order=[sys],once=d,menu=off
Yes, this looks powerful and clean. One could even still define probe orders like "-boot order=[sys][backup]d".
Well, except that boot orders with two hard drives in there don't work in the PC world ...
- This is just an implementation detail: Do we really need to implement booting from virtio and scsi via an extension rom? Isn't it possible to merge the corresponding support into the main bios?
Well. There are quite a few. bochs pcbios, seabios, coreboot ...
Ok, but that's only an argument to have extboot as a workaround for bioses not yet supporting scsi and virtio natively, isn't it? I'm thinking long-term here, not arguing against a extboot-based short-term solution.
I think it would be useful. Adding a fw_cfg knob to signal 'please boot via extboot protocol instead of ide disk' should be enougth to allow bioses supporting extboot directly. Additional plus is we can probably code it in C not asm then. cheers, Gerd