[Libvir] [PATCH] Allow modifying existing block device, making virDomainAttachDevice modify the device if it already exists

The attached patch adds code to xend_internal.c:xenDomainAttachDevice that checks to see if the device mentioned in the passed-in XML already exists, and if so calls op_device_configure to modify the device. It is particularly useful for connecting and disconnecting a hardware cdrom device to an FV guest. I considered making new API a la virDomainModifyDevice, but decided overloading virDomainAttachDevice was cleaner (and didn't change existing API). I have tested the patch on f7 with xen 3.1 and a windows 2000 guest. Since the patch merely wraps Xen's device_configure call, we're not adding much risk of breakage. Please ACK. Take care, --Hugh -- Red Hat Virtualization Group http://redhat.com/virtualization Hugh Brock | virt-manager http://virt-manager.org hbrock(a)redhat.com | virtualization library http://libvirt.org