Re: [Qemu-devel] [PATCHv2] seabios: enable io/memory unconditionally

[Kevin O'Connor]

Hi Michael,

On Thu, Oct 08, 2009 at 05:53:46PM +0200, Michael S. Tsirkin wrote:
> VGA adapters need to claim memory and i/o
> transactions even if they do not have any
> i/o or memory bars. E.g. PCI spec, page 297,
> gives an example of such a device:
> 
>     Programming interface 0000 0000b
>     VGA-compatible controller. Memory
>     addresses 0A 0000h through 0B
>     FFFFh. I/O addresses 3B0h to 3BBh
>     and 3C0h to 3DFh and all aliases of
>     these addresses.
> 
> While we could check for these devices and special-case them, it is
> easier to fix this by enabling i/o and memory space unconditionally:
> devices that do not support it will just ignore this setting.

This doesn't sound correct to me - I would think the vga option rom
should enable the memory and io bars.  I don't have enough knowledge
to say for sure though - can someone else with knowledge in this area
confirm this approach?

-Kevin