[OpenBIOS] [PATCH] pci: enable io/memory unconditionally

[Laurent Vivier]

>On Thu, Dec 10, 2009 at 01:09:34PM +0100, Laurent Vivier wrote:
>> >On Thu, Dec 10, 2009 at 01:20:23AM +0100, Laurent Vivier wrote:
>> >> Le mercredi 09 décembre 2009 à 17:53 +0200, Michael S. Tsirkin a écrit :
>> >> > 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 bios 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.
>> >> > 
>> >> > Signed-off-by: Michael S. Tsirkin <mst at redhat.com>
>> >> 
>> >> Applied, but could you give me an use case where previous behavior
>> >> breaks something ?
>> >> 
>> >> Regards,
>> >> Laurent
>> >
>> >qemu uses openbios and implements cirrus vga emulation,
>> >which has this device class and no IO bars.
>> 
>> qemu-system-ppc doesn't support cirrus vga emulation (only vga emulation), 
>moreover openbios is not able to manage cirrus vga card.
>
>Maybe it will support it in the future :).

Are you working on this ?

>> So why this modification is needed ?
>> (even if it is correct according to the specs, it's why I've applied it)
>
>It's not fixing any breakage I have observed, if that's what you mean.
>I found the issue in bochs bios and seabios with
>cirrus vga emulation, so I thought I'd fix up openbios as well.

OK, it's fine for me. Thank you.

Laurent
-- 
--------------------- Laurent at vivier.eu  ---------------------
"Tout ce qui est impossible reste à accomplir"    Jules Verne
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