[Qemu-devel] Re: [PATCH 1/6] Make config space accessor host bus trapable

[Alexander Graf]

On 03.01.2010, at 21:50, Benjamin Herrenschmidt wrote:

> On Sun, 2010-01-03 at 21:27 +0100, Alexander Graf wrote:
> 
>> I think if unin_pci is the only user, it'd be better to do it hacky
>> inside unin_pci.c. But if there's a chance there's another user, it'd
>> be better to make it generic.
>> 
>> Since this is the first time I ever stumbled across type 0 and type 1
>> PCI config space addresses, I simply don't know if there are any. Blue
>> Swirls comment indicated that there are. Ben also sounded as if it's
>> rather common to not use the x86 format. On the other hand, it looks
>> like nobody in qemu needed it so far - and we're implementing ARM,
>> MIPS and all other sorts of platforms.
>> 
>> So if anyone with knowledge in PCI could shed some light here, please
>> do so.
> 
> My feeling is that what you're better off doing is to have the qemu core
> take an abstract struct to identify a device config space location, that
> consists of separate fields for:
> 
> - The PCI domain (which is what host bridge it hangs off since bus
> numbers are not unique between domains)
> 
> - The bus number

Hm, I think it'd make more sense to just store a PCIBus pointer in there. We 
could then fetch the bus and domain id from there.

I'll write something up :-).


Alex