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
* src/qemu/qemu_conf.c: add the ",readonly=on" for read-only disks
and also parse it back in qemuParseCommandLineDisk()
* tests/qemuxml2argvtest.c
tests/qemuxml2argvdata/qemuxml2argv-disk-drive-readonly-disk.args
tests/qemuxml2argvdata/qemuxml2argv-disk-drive-readonly-disk.xml:
add a specific regression test
