[Libvir] [PATCH] Add virConnectGetCapabilities call to return the capabilities of the driver / hypervisor

This patch: * Adds virConnectGetCapabilities which returns an XML description of the capabilities of the driver or hypervisor under this connection (see below for more about the XML format). * Adds virsh capabilities command. * Checks the Python binding works. Caveats: * Xen implementation (in xen_internal.c) is not tested because I don't have a working Xen machine right now. QEMU, test and remote work however. Example: $ virsh -c test:///default capabilities | tidy -xml -i -q <capabilities> <domain> <type>test</type> </domain> <host_features></host_features> <guest_architectures> <guest_architecture> <model>i686</model> <bits>32</bits> <guest_features> <accelerated /> <pae /> </guest_features> </guest_architecture> </guest_architectures> </capabilities> $ virsh -c qemu:///session capabilities | tidy -xml -i -q <capabilities> <domain> <type>qemu</type> </domain> <guest_architectures> <guest_architecture> <model>i686</model> <bits>32</bits> <features> <emulated /> </features> </guest_architecture> <guest_architecture> <model>x86_64</model> <bits>64</bits> <features> <emulated /> </features> </guest_architecture> [... other archs deleted ...] </guest_architectures> </capabilities> XML format: The <capabilities> node contains information about the host and a list of supported architectures for guests. About the host we return: <domain> <type> The default type acceptable when creating a domain. <host_features> <hvm> Does the host CPU support HVM? <type> Type of HVM (eg. "vmx") <bios_setting> "enabled" or "disabled" About the guest architectures we can return: <guest_architecture> <model> The (virtualised) CPU <bits> Bits <domain> <type> If different from the default type (eg. for kqemu) <features> <hvm> Full virt guest? <accelerated> Accelerated (eg. Xen or kqemu) <emulated> Emulated (eg. qemu or bochs) (and a few other esoteric flags here) Rich. -- Emerging Technologies, Red Hat http://et.redhat.com/~rjones/ 64 Baker Street, London, W1U 7DF Mobile: +44 7866 314 421 "[Negative numbers] darken the very whole doctrines of the equations and make dark of the things which are in their nature excessively obvious and simple" (Francis Maseres FRS, mathematician, 1759)