[OpenBIOS] [PATCH] pci: fix BAR setup

[Blue Swirl]

On Mon, May 14, 2012 at 1:49 PM, Mark Cave-Ayland
<mark.cave-ayland at ilande.co.uk> wrote:
> On 14/05/12 14:28, Artyom Tarasenko wrote:
>
>>>> 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...
>
>
> I'm not sure I'm confident enough with PCI to do this, and I'm also not sure
> what Blue's recommended fix actually is? Is it to increase parent_base by
> 0x1000 or set child_base to zero?

The best solution is to fix VGA (assuming my analysis was right) and
set child_base to zero.

But while waiting for that to happen, we could adjust base arithmetic
somehow so that HelenOS boots and also the VGA areas are avoided.

>
>
> ATB,
>
> Mark.
>
>
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