PCI mmap - How do I access a PCI board address space?

[Angelo Fraietta]

gregory.menke at gsfc.nasa.gov wrote:

>Chris Caudle writes:
> > gregory.menke at gsfc.nasa.gov wrote:
> > > Yes, though now they are often implemented as #defines.  On the x86,
> > > you have IO and memory accesses, so the operations are different. 
> > 
> > On PCI based systems running in protected mode, IO access is
> > considered just one step short of deprecated.  PCI spec recommends
> > memory access only, and some newer PCI devices do not implement I/O
> > access at all.  Because of legacy support, i.e. even the newest X86
> > servers can still boot DOS, devices which can be boot devices
> > typically still implement I/O access, but it is for legacy support
> > only.
> > 
>
>Better tell 3-Com; etherlink devices have historically worked in IO
>space, and they continue to, lots of other devices are memory only.
>It doesn't really matter much either way.  Some hardware is better
>suited to IO mapping than memory mapping.
>
>  
>
This is defininately the case with the DIMM-PC which runs the pc386dx 
BSP. You have to use mapped I/O because you can't memory map the 
external device..

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Angelo Fraietta

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