[libvirt] [PATCH 0/3] add pci-bridge device and address type

[liguang]

Now, it's unnecessary to arrange devices into multi-pci-bus,
for example:
    <sound model='ac97'>
      <address type='pci' domain='0x0000' bus='0x00' slot='0x04' function='0x0'/>
    </sound>
   <video>
      <model type='cirrus' vram='9216' heads='1'/>
      <address type='pci' domain='0x0000' bus='0x1' slot='0x02' function='0x0'/>
    </video>
libvirt will complain about "bus != 0",
fortunately, qemu supports pci-to-pci bridge,
if we want to use multi-pci-bus, we can define
2 pci bridge devices then attach 1 to the other
as a subordinate pci-bus, so, 2 pci-buses appear.
for example:
    <pci-bridge type='root'/>
    <pci-bridge type='subordinate'>
      <address type='pci-bridge' domain='0x0000' bus='0x00' slot='0x04' function='0x0'/>
    </pci-bridge>
    <sound model='ac97'>
      <address type='pci-bridge' domain='0x0000' bus='0x01' slot='0x02' function='0x0'/>
    </sound>
   <video>
      <model type='cirrus' vram='9216' heads='1'/>
      <address type='pci-bridge' domain='0x0000' bus='0x00' slot='0x02' function='0x0'/>
    </video>

 src/conf/domain_conf.c		 |   88 +++++++++++++++++++++++++++++++++++++++++++++---
 src/conf/domain_conf.h 	 |   22 ++++++++++++
 src/qemu/qemu_command.c 	 |   52 +++++++++++++++++++++++++++++++++++++++++++---
 docs/formatdomain.html.in	 |   23 +++++++++++++++++++++++
 4 files changed, 176 insertions(+), 9 deletions(-)