Re: [Qemu-devel] [PATCH] all vga: refuse hotplugging.

[Gerd Hoffmann]

On 05/26/10 12:59, Stefano Stabellini wrote:
> On Wed, 26 May 2010, Gerd Hoffmann wrote:
> > Try to pci hotplug a vga card, watch qemu die with hw_error().
> > This patch fixes it.
>
> Do you know the reason why we get hw_error()?

Because the card tries to register the legacy vga ports which are 
already taken by the primary card.  I also don't know whenever you can 
pci hot-plug hardware which uses non-pci ressources at all.

> Theoretically vga hotplug should be possible at least for secondary
> graphic cards (even though I suspect most operating systems wouldn't
> cope).

Yes.  Assuming the virtual hardware in question can actually act as 
secondary, i.e. is fully programmable without the legacy vga ports.  The 
standard vga can't.  The cirrus looks doable, at least you can access 
the vga ports using the mmio bar.

cheers,
  Gerd