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

[gregory.menke at gsfc.nasa.gov]

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.

What does protected mode or DOS have to do with anything?  If Intel
wants to get rid of IO space, thats fine- but its essentially
unrelated to PCI.  I agree IO space is kind of annoying sometimes but
theres nothing wrong with it functionally.  Sometimes its kind of nice
to have your hardware orthogonal to your program/data store.

Gregm