Re: [OpenBIOS] [PATCH] pci: fix BAR setup

[Mark Cave-Ayland]

On 12/05/12 10:11, Blue Swirl wrote:
> > Agreed. On current SPARC, the only non-zero Range on PCI is for 64-bit
> > memory. For the memory ranges we see:
> >
> > 0200.0000 0000.0000 0000.0000 8000.8090 0000.0000 0000.0007 0000.0000
> > 0300.0000 0000.0001 0000.0000 8000.8091 0000.0000 0000.0007 0000.0000
> >
> > My recollection is that memory space PCI RA (real address rather than
> > physical address, because now we're behind a hypervisor) ranges from
> > 8000.8090.0000.0000 through 8000.8097.FFFF.FFFF - which would match your
> > guess that the parent_base needs to be hacked if 0800.0000 is going to be
> > the BAR and is going to represent 1ff.0800.0000.
> >
> > So, why does OpenBios have 0100.0000 as a child base in the first place?
>
> It's to avoid VGA legacy mapping at 0xa0000. If I change
> hwdefs.pci.pci_mem_base in arch/sparc64/openbios.c to 0, OpenBIOS will
> crash during VGA init. Previously this worked because the PCI devices
> were mapped somewhat randomly and by chance, VGA legacy low mem area
> was avoided.
>
> I think the correct fix is to make QEMU VGA device disable the legacy
> mapping unless explicitly enabled. Alternatively the child base
> arithmetic could be fixed in OpenBIOS like proposed by Jakub.

Did a patch ever come out of this discussion in the end?

ATB,

Mark.

[PATCH] pci: fix BAR setup

[Artyom Tarasenko]

On Mon, May 14, 2012 at 3:07 PM, Mark Cave-Ayland
 wrote:
> On 12/05/12 10:11, Blue Swirl wrote:
> > > Agreed. On current SPARC, the only non-zero Range on PCI is for 64-bit
> > > memory. For the memory ranges we see:
> > >
> > > 0200.0000 0000.0000 0000.0000 8000.8090 0000.0000 0000.0007 0000.0000
> > > 0300.0000 0000.0001 0000.0000 8000.8091 0000.0000 0000.0007 0000.0000
> > >
> > > My recollection is that memory space PCI RA (real address rather than
> > > physical address, because now we're behind a hypervisor) ranges from
> > > 8000.8090.0000.0000 through 8000.8097.FFFF.FFFF - which would match your
> > > guess that the parent_base needs to be hacked if 0800.0000 is going to be
> > > the BAR and is going to represent 1ff.0800.0000.
> > >
> > > So, why does OpenBios have 0100.0000 as a child base in the first place?
> >
> > It's to avoid VGA legacy mapping at 0xa0000. If I change
> > hwdefs.pci.pci_mem_base in arch/sparc64/openbios.c to 0, OpenBIOS will
> > crash during VGA init. Previously this worked because the PCI devices
> > were mapped somewhat randomly and by chance, VGA legacy low mem area
> > was avoided.
> >
> > I think the correct fix is to make QEMU VGA device disable the legacy
> > mapping unless explicitly enabled. Alternatively the child base
> > arithmetic could be fixed in OpenBIOS like proposed by Jakub.
>
> Did a patch ever come out of this discussion in the end?

No. :-) Feel free to fix it, unless Blue prefers fixing it himself...