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

[Michael S. Tsirkin]

On Sun, Mar 04, 2012 at 12:46:23PM +0000, Blue Swirl wrote:
> On Sun, Mar 4, 2012 at 12:41, Avi Kivity <address@hidden> wrote:
> > On 03/04/2012 02:38 PM, Blue Swirl wrote:
> >> >>
> >> >> This unassigned memory exception is triggered because CMD646 IDE I/O
> >> >> registers are not accessible:
> >> >>
> >> >> (qemu) info pci
> >> >>   Bus  0, device   5, function 0:
> >> >>     IDE controller: PCI device 1095:0646
> >> >>       IRQ 1.
> >> >>       BAR0: I/O at 0xffffffffffffffff [0x0006].
> >> >>       BAR1: I/O at 0xffffffffffffffff [0x0002].
> >> >>       BAR2: I/O at 0xffffffffffffffff [0x0006].
> >> >>       BAR3: I/O at 0xffffffffffffffff [0x0002].
> >> >>       BAR4: I/O at 0xffffffffffffffff [0x000e].
> >> >>       id ""
> >> >
> >> > The BARs are not initialized, so they aren't accessible.
> >> >
> >> > But perhaps the dump was not taken at the point of failure, can you
> >> > provide a relevant dump if so?
> >>
> >> No, this is after failure.
> >
> > I don't see why the guest expects the BARs to work then.
> 
> OpenBIOS could initialize them before this commit, now it obviously
> can't (or initializes the bridges incorrectly).

I traced all config reads and writes to the bridge
and there's no difference I can see
between before and after this commit.

I think there's some other bug, tweaking this
specific bit just happens to trigger it.

> Maybe also the devices should be moved behind the bridges, that's
> where they really should be.
> 
> >
> > --
> > error compiling committee.c: too many arguments to function
> >