On 08/02/2013 12:42 AM, Eric Blake wrote:
On 08/01/2013 04:23 PM, Paolo Bonzini wrote:
Automatic devices with no command line argument have proven to be a nightmare for libvirt as well. Although the just-released libvirt 1.1.1 now supports the <on_crash> element for controlling the command line parameters of qemu related to how qemu will behave when the pvpanic device is triggered, I would also welcome having the ability to control whether the guest even has a pvpanic device exposed, just as we can control whether a guest has a memballoon device exposed.
This is quite different from memballoon.
pvpanic is a single I/O port, it doesn't use up a PCI slot (thus causing conflicts with other devices at the same address).
Perhaps this issue is simply fixed by making the _STA method return 0x0B instead of 0x0F (i.e. turning off the "show in user interface" bit).
That may "fix" the issue of a windows guest showing the yellow ! mark, but what if, down the road, someone writes an actual windows driver that is aware of that port and how to make a windows BSOD write a panic notification to the port? How does a user go about installing such a driver if the device is not exposed in the user interface list of devices?
The user can still manually install a driver even for a device that is not exposed. Having to manually specify the pvpanic device would be yet another knob that nobody uses. Panic notification is a useful feature that should be supported with no particular intervention from the user. Paolo