[Qemu-devel] Re: [PATCH 0/2] port over extboot from kvm

[Gerd Hoffmann <kraxel@redhat.com>]

On 09/08/09 15:47, Jan Kiszka wrote:

> Before setting this definitely useful feature in stone, I have two
> questions though:
>
>   - -drive ...,boot=on is logically in conflict with -boot. Yes, -boot
>     for x86 currently cannot differentiate between multiple disks, only
>     between boot media types. Still, this two-stage configuration is
>     rather unintuitive and looks like a patchwork. Given that we have
>     full control over all components, is it really the preferred
>     approach? I already thought about, e.g., -boot c2 to select the
>     second disk. Not that nice, but I would rather vote for a consistent
>     configuration than a scattered one.

Disk numbers are bad.  Define "second hard disk".  Especially for a 
system with different kinds of disks (say one scsi and one virtio).

Drives have names though which can be used to reference the disks, so we 
could use that instead.  -boot cmd line syntax becomes a bit tricky then 
though, we somehow have to figure whenever the user gave us names or 
old-style letters.  Something like this ...

   -drive if=virtio,id=sys,file=/path/to/disk.img
   -cdrom /path/to/install.iso
   -boot order=[sys],once=d,menu=off

... might work out nicely.  I suspect the libvirt folks will hate us for 
that though.

>   - 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 ...

cheers,
   Gerd