I re-worked the patch. This time it uses fixmap; I added config 
parameters to
disable this code and to handle non-default base address.
Unless generic solution for auto detection found, it seems appropriate
way to go.

Autodetection problem isolated in 2 places: is_pcie_platform and, while 
it is not
do real auto detection, configuration option for custom base.

Vladimir.

Linus Torvalds wrote:

>On Mon, 15 Dec 2003, Vladimir Kondratiev wrote:
>  
>
>>There is alternative solution, for each transaction to ioremap/unmap
>>corresponded page.
>>    
>>
>
>Nope, you can't do that. It's not really supported from interrupts and
>early boot - both of which will want to access PCI config space.
>
>  
>
>>I don't like it, it involves huge overhead.
>>    
>>
>
>Indeed it would. But using fixmaps does _not_.
>
>But a fixmap will be easy to use, and reasonable efficient: it will
>allocate just one virtual page, and then it will force a TLB flush when it
>switches over the mapping.
>
>You can improve the efficiency by caching the "last fixmap entry" and only
>doing "set_fixmap()" when changing devices.
>
>You could also do a per-cpu fixmap, which would help further, but that
>ends up being more work too. Probably not worth it, especially as it is
>entirely possible that the hardware requires single-threaded access
>anyway (ie I would not be surprised at all if the southbridge got very
>confused if you tried to do overlapping config accesses)..
>
>		Linus
>  
>