[libvirt] [BUG] Fix order of disks and controllers

[Philipp Hahn]

Hello,

On Wednesday 01 June 2011 17:58:32 Jiri Denemark wrote:
> Commit 2d6adabd53c8f1858191d521dc9b4948d1205955 replaced qsorting disk
> and controller devices with inserting them at the right position. That
> was to fix unnecessary reordering of devices. However, when parsing
> domain XML devices are just taken in the order in which they appear in
> the XML since. Use the correct insertion algorithm to honor device
> target.

This commit (c1a98d88255197a8446d08c0b1589861660e9064) broke the Xen-PC-PyGrub 
case (see also "[PATCH 3/4] xen: fix PyGrub boot device order" from Oct 12th 
2011, which worked only for preious versions of libvirt):
XenD used the order of disks on domain-to-native to set the bootable flag to 1 
only for the first device. This flag is then used on domain-start to 
determine the disk, which gets passed ty PyGrub to extract the Kernel and 
IniRD.
Now the order is determined by /domain/devices/disk/target/@dev, which makes 
chaning the order impossible without also changing the devices names, which 
are visible to the VM! The Nr. 1 use-case for this is chaning the boot-order 
after installing from a PV-CDROM to the PV-disk.
Since the Xen-PV-case has no BIOS bootable section, using /domain/os/boot/ 
here does not work.

Either that libvirt needs to explicitly support Xens bootable flag 
(via /domain/devices/disk/boot/@order?), or this patch should be reverted.
Comments?

Sincerely
Philipp
-- 
Philipp Hahn           Open Source Software Engineer      hahn at univention.de
Univention GmbH        Linux for Your Business        fon: +49 421 22 232- 0
Mary-Somerville-Str.1  D-28359 Bremen                 fax: +49 421 22 232-99
                                                   http://www.univention.de/
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