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

[Yinghai Lu <yinghai@kernel.org>]

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@kernel.org>
>>
>> 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