To allow compatibility with older QEMU PCI device slot assignment
it is necessary to explicitly track the balloon device in the
XML. This introduces a new device
<memballoon model='virtio|xen'/>
It can also have a PCI address, auto-assigned if necessary.
The memballoon will be automatically added to all Xen and QEMU
guests by default.
* docs/schemas/domain.rng: Add <memballoon> element
* src/conf/domain_conf.c, src/conf/domain_conf.h: parsing
and formatting for memballoon device. Always add a memory
balloon device to Xen/QEMU if none exists in XML
* src/libvirt_private.syms: Export memballoon model APIs
* src/qemu/qemu_conf.c, src/qemu/qemu_conf.h: Honour the
PCI device address in memory balloon device
* tests/*: Update to test new functionality
The previous syntax was severely limited in its options
-usbdevice disk:/home/berrange/output.img
The new syntax is the same as for other disk types
-drive file=/home/berrange/output.img,if=none,id=usb-1,index=1
-device usb-storage,drive=usb-1
Again, the index= arg is wrong here, and will be removed in a
later merge
