[SeaBIOS] [PATCH] don't expose pvpanic device in the UI

[Paolo Bonzini]

> > That's just pushing the problem elsewhere. How management suppose to know
> > if guest support pvpanic device?
> 
> The problem isn't new and management already does that when figuring
> whenever the guest should get ide/ahci/virtio-blk/virtio-scsi storage,
> ac97 or intel-hda sound, rtl8139/e1000/virtio nic, ...

Depending on the management, "management" could just be the user.
Most of the time the user simply says to use virtio in the XML.

If it had to be specified manually every time, pvpanic would be
just another knob that nobody uses.  The point of pvpanic was to
be as automatic and unobtrusive as possible.

Replying to Eric's concerns, drivers can be installed anyway even
if the devices are hidden.  Windows will detect that the driver
matches the ACPI ID of pvpanic (QEMU0001) and install it.

Resetting bit 2 is Microsoft's suggested way to hide devices, even
broken ones (i.e. with bit 3 = 0 in _STA).  See
http://msdn.microsoft.com/en-us/library/windows/hardware/ff547032(v=vs.85).aspx
for more information.  The document also mentions that it is
possible to show hidden devices, at which point the user will
see pvpanic.  In this case, having the exclamation mark is good
and expected, since the lack of a driver is real.

(Besides, I would not be much worried about Microsoft's choice of
icons.  I doubt a machine would be considered "not healthy" just
because the "missing driver" icon looks worrisome).

Paolo