Re: [Qemu-ppc] [Qemu-devel] [PATCH] PPC: fix PCI configuration space MemoryRegions for grackle/uninorth

[Mark Cave-Ayland]

On 08/11/13 03:20, Alexander Graf wrote:

> On 11.10.2013, at 12:53, Mark Cave-Ayland<address@hidden>  wrote:
>
> > OpenBIOS prior to SVN r1225 had a horrible bug when accessing PCI
> > configuration space for PPC Mac architectures - instead of writing the PCI
> > configuration data value to the data register address, it would instead write
> > it to the data register address plus the PCI configuration address.
> >
> > For this reason, the MemoryRegions for the PCI data register for
> > grackle/uninorth were extremely large in order to accomodate the entire PCI
> > configuration space being accessed during OpenBIOS PCI bus enumeration. Now
> > that the OpenBIOS images have been updated, reduce the MemoryRegion sizes down
> > to a single 32-bit register as intended.
> >
> > Signed-off-by: Mark Cave-Ayland<address@hidden>
> > CC: Hervé Poussineau<address@hidden>
> > CC: Andreas Färber<address@hidden>
> > CC: Alexander Graf<address@hidden>
>
> With this patch applied, mac99 emulation seems to break:
>
>    
> http://award.ath.cx/results/288-alex/x86/kvm.qemu-git-tcg.ppc-debian.mac99-G4.etch.e1000.reboot/debug/serial-vm1.log
>
>
> Alex

Hi Alex,

Thanks for the heads-up - with the information above I was able to 
reproduce this fairly easily. I had look at some of the uninorth 
drivers, and while it's not particularly apparent from Linux that the 
PCI configuration data is accessed via MMIO rather than ioport access, 
FreeBSD seems to suggest that this is the case: 
http://code.google.com/p/freebsd-head/source/browse/sys/powerpc/powermac/uninorth.c?spec=svnc6989e24706228678e454517dad4ad465a36e556&r=c6989e24706228678e454517dad4ad465a36e556#274.

The key is that the QEMU uninorth host bridge contains a hack to allow 
PCI configuration mechanism #1 as used by OpenBIOS to work at all (see 
unin_get_config_reg() in hw/pci-host/uninorth.c) which is why I didn't 
notice it in my OpenBIOS boot tests; and in fact, the name of the 
uninorth PCI configuration data MemoryRegions have a "-data" rather than 
a "-idx" suffix is also a big clue.

Hence please find a revised version of the patch which is unaltered for 
grackle, and only changes the MemoryRegion size for the PCI 
configuration address register for uninorth so that the PCI 
configuration data space is still accessible using MMIO. This resolves 
the issue for me, so if you're satisifed that it works for you then I'll 
post a revised version to the list.


ATB,

Mark.

qemu-ppc-pci-fix.patch
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