[libvirt] Re: [PATCH 0/2] port over extboot from kvm
Jan Kiszka
jan.kiszka at siemens.com
Tue Sep 8 16:15:27 UTC 2009
Gerd Hoffmann wrote:
>>> -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 ...
That depends on your bios. I've seen many that allow disk boot ordering,
though they may not support "[sys]d[backup]".
However, I see no technical reason for artificially restricting qemu
bios capabilities.
>
>>>> - 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.
I'm still not convinced we need extboot for all bioses on the long term.
And I think we should define new interfaces in a way that finally makes
it obsolete, at least for our "home bios" (whatever it will be).
Jan
--
Siemens AG, Corporate Technology, CT SE 2
Corporate Competence Center Embedded Linux
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