Originally reported on https://bugs.launchpad.net/ubuntu/+source/virt-manager/+bug/245107 When I change the hardware configuration for a running virtual machine, using virt-manager, it does not work. That's OK, changing hardware while a machine is running is usually not something works on real hardware either. The problem here is one of usability: either virt-manager should not let me add the hardware, or it should tell me that the hardware change will occur when the virtual machine is booted up the next time. Right now, it gives me an error message saying that it couldn't add the hardware, yet it is there when the virtual machine boots.
This is fixed in virt-manager 0.6.0: if we can't hotplug the hardware, we pop up a dialog warning the user that attach will only take effect after next VM reboot. Closing as CURRENTRELEASE.
Thank you, Cole, for your quick answer and telling us that this is fixed.