[OpenBIOS] [PATCH] pci: fix BAR setup

Artyom Tarasenko atar4qemu at gmail.com
Fri Apr 19 23:10:39 CEST 2013

On Mon, May 14, 2012 at 8:58 PM, Blue Swirl <blauwirbel at gmail.com> wrote:
> 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.

Blue, do you know whether the QOMification improved the situation with
the legacy VGA low mem area?

Artyom Tarasenko

linux/sparc and solaris/sparc under qemu blog:

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