Re: BAR Conflict

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On 2011-08-04 05:14, Konrad Rzeszutek Wilk wrote:
>>>>>> and kvm does not want to go further. dmesg, /proc/iomem and lspci are at
>>>>>> the end of this email.
>>>>>> The memory reserved by BIOS-e820
>>>>>> [    0.000000]  BIOS-e820: 00000000fa000000 - 00000000fc000000
>>>>>> (reserved)
>>>>>> Quadro 2000 is 05:00.0 and its conflicting BAR is
>>>>>>        Region 3: Memory at f8000000 (64-bit, prefetchable) [disabled]
>>>>>> [size=64M]
>>>>>> and its upstream bridge 00:1c.00
>> OK, if it's safe to ignore for PCI allocations, then ignore the
>> reservation. But I think that should be done automatically if somehow
>> possible, not by the user via a kernel parameter.
>>
>> Is there a simple way to test such a policy without significant
>> refactoring of the e820 code?
> 
> Why not just make the kvm PCI passthrough code check the MMIO
> of the card and make an "gap" in the E820 for that region. In essence
> creating a PCI I/O region?
> 
> Why does QEMU setup up that reserved region? Can it move it?

I really don't think this is KVM business. The fact that also nouveau
and nvidia's blob complain or even stumble (Maxim is checking if the
hack also heals the latter) and both are using a standard PCI core
service to request the card resources strongly suggests that the problem
should not be attacked by some ad-hoc workaround in KVM.

Jan

-- 
Siemens AG, Corporate Technology, CT T DE IT 1
Corporate Competence Center Embedded Linux
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