Re: [Qemu-devel] [PATCH] pci: fix bridge IO/BASE

["Michael S. Tsirkin" <mst@redhat.com>]

On Mon, Mar 05, 2012 at 06:34:51PM +0000, Blue Swirl wrote:
> On Sun, Mar 4, 2012 at 22:29, Michael S. Tsirkin <mst@redhat.com> wrote:
> > On Sun, Mar 04, 2012 at 09:54:02PM +0000, Blue Swirl wrote:
> >> >> 19.3.1.10 tells that the header type is 0, as you noted too. Still,
> >> >> the register layout matches bridge spec instead, for example there are
> >> >> bus number registers in place of BAR 2.
> >> >
> >> > Sorry I don't see this in 19.3.1
> >> > Where are these registers documented?
> >> > In my spec all registers from 0x10 on are greyed out which
> >> > it says above means 'not implemented'?
> >> > My spec also says 'Base Address' for 0x10 - 0x27.
> >> >
> >> > I see bus number and subordinate bus number
> >> > registers at 0x40 and 0x41, this is outside
> >> > the configuration header. The spec also says
> >> > they are unused.
> >>
> >> Oh, I somehow read that they were in bridge locations 0x18 and 0x19.
> >> Perhaps the is_bridge property should be removed after OpenBIOS no
> >> longer wants to write to the registers.
> >
> > So we are in agreement then?
> > The device seems to (more or less) go by the spec,
> 
> QEMU is correct here as is your original commit. The only change
> (beside bug fixes for the problems you found, thanks) should be for
> is_bridge.

You mean remove is_bridge? Right.

> > but openbios gets confused, apparently by the absence of BARs.
> >
> > Can you try debugging openbios to see what is wrong?
> 
> On second thought, I think 32 bit I/O was confusing OpenBIOS, probably
> the host bridge device not so much. PCI handling in OpenBIOS should be
> fixed.

We can make IO 32 bit. Want to try?
Anyway, so I won't revert this in core for now?

> > --
> > MST