Re: [Qemu-devel] [Resend][Seabios PATCH] don't boot from un-selected devices

[Amos Kong <akong@redhat.com>]

On Wed, Dec 19, 2012 at 08:38:13AM +0100, Gerd Hoffmann wrote:
> On 12/19/12 08:24, Amos Kong wrote:
> > Current seabios will try to boot from selected devices first,
> > if they are all failed, seabios will also try to boot from
> > un-selected devices.
> > 
> > For example:
> > @ qemu-kvm -boot order=n,menu=on ...
> > 
> > Guest will boot from network first, if it's failed, guest will try to
> > boot from other un-selected devices (floppy, cdrom, disk) one by one.
> > 
> > Sometimes, user don't want to boot from some devices. This patch changes
> > seabios to boot only from selected devices.
> 
> I think (i.e. I didn't test) the patch breaks booting if the user didn't
> explicitly specify a boot device.

Hi Gerd,

| #define DEFAULT_PRIO           9999

If we don't select some devices, their priority will always be 9999
 
| static int DefaultFloppyPrio = 101;
| static int DefaultCDPrio     = 102;
| static int DefaultHDPrio     = 103;
| static int DefaultBEVPrio    = 104;
 
The priority of selected devices will be changed to above values
first, the priority might be re-changed.

However, we can judge if device is selected or not by checking if the
priority is 9999.

. Boot guest without qemu boot option, guest will try to boot from
  network/hd/floppy/cdrom.

. If seabios ignores the order parameter of qemu, guest will also try
  to boot from network/hd/floppy/cdrom.

-- 
		Amos.