Re: [Qemu-devel] [PATCH 1/6] bootindex: add {del, modify}_boot_device_path function

[Gerd Hoffmann <kraxel@redhat.com>]

  Hi,

> > Hmm.  I think we should simply lookup the device and modify the
> > bootindex, leaving the entry as-is otherwise.  In case the new bootindex
> > is already used by another device just throw an error.
> > 
> If we just throw an error but not change the bootindex is already used,
> we cannot achieve our purpose. For example, we configure a hard disk,
> which bootindex=1, a nic which bootindex=2. If we want to boot the guest
> from nic firstly, we should must set the nic's bootindex to 1. AFAICT, the 
> bootindex=1 always be used.

No.  The devices are simply sorted by bootindex.  You don't have to use
'1'.  And you can have holes in your numbering and use --for example --
3+5.

So you can start qemu with hd=2,cdrom=3,nic=4, then set nic=1 or cdrom=1
for a guest install, change it back when done.

> > Should be del_boot_device_path(DeviceState *dev) and simply delete all
> > entries belonging to the device.  Patch #3 can be much simpler then as
> > we can call the function from generic device cleanup code.
> > 
> Because the IDE device may configure two kind of disk, HD and CDROM, we
> have to distinguish them by suffix.

Yes, the suffix indicated whenever the device is a disk or cdrom.  But
you'll never have both cdrom+disk paths attached to a single device.
Therefore the device is enough to identify the bootpath entry, you don't
need the suffix for that.

cheers,
  Gerd