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

[Isaku Yamahata]

On Mon, Jan 04, 2010 at 11:55:10AM +0100, Alexander Graf wrote:
> 
> On 04.01.2010, at 11:45, Isaku Yamahata wrote:
> 
> > On Mon, Jan 04, 2010 at 04:26:46AM +0100, Alexander Graf wrote:
> >> 
> >> 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
> >> 
> > 
> > Does the following patch help?
> > I did only compile test though.
> 
> I sent out v2 already, which contains a complete resolution framework. It 
> also allows for incremental cleanup of the users, as I'd rather like to see 
> everyone use pci_host instead of hacky homegrown functions. But I don't think 
> changing all at once is going to fly wrt reviewablity.

Agreed. Anyway that patch is just for discussion, not for commit.
If wanted, I'm willing to split it up into a series of patches or
rebase it on top of your patches. (Or throw it away)


> I'd be really glad if you could take a glimpse at my version. You're 
> definitely more knowledgable in the PCI areas than me :-). I verified that it 
> fixes Uninorth and x86 still works.

I'll have a look at it tomorrow.

-- 
yamahata