Re: [PATCH] x86/pci: try to detect host_bridge pci_cfg_space

From: Yinghai Lu
Date: Fri Mar 06 2009 - 20:08:19 EST


H. Peter Anvin wrote:
> H. Peter Anvin wrote:
>> Yinghai Lu wrote:
>>> Impact: get correct pci_cfg_size for host_bridge
>>>
>>> more host bridges support 4k cfg, so check them directly
>>> instead of quirks.
>>>
>>> Signed-off-by: Yinghai Lu <yinghai@xxxxxxxxxx>
>>
>> I'm utterly confused by this. This is basically saying we should try
>> to probe for an extended device space for every host bridge.
>> Logically speaking, this is valid: if there is a valid path by which
>> we can probe for byte 256 then it should succeed.
>>
>> HOWEVER, the same argument applies for *every single device*. So if
>> this does indeed work, why should we limit it to host bridges?
>>
>
> Looking at the code (as opposed to just the patch) made it a bit
> clearer. The argument you're making here is that only host bridges are
> known to have extended address space without also having a PCI-X
> extension header, right?


Yes.

YH

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