On other architectures that have memory mapped I/O, things are more complex
because the addresses are not fixed. They may even be different for different
machines within the same architecture. E.g. on Linux/PPC, this is the case for
the PReP and CHRP platforms. So the application has to be informed of the base
addresses to mmap.
One solution would be to add 2 lines to /proc/cpuinfo, like
isa_io_base: 0xf8000000
isa_mem_base: 0xf7000000
(for CHRP LongTrail).
Another solution (IMHO better) would be to add /proc/bus/isa/io and
/proc/bus/isa/mem. On machines with memory mapped I/O, you can mmap() these, on
ordinary PCs you have to use read/write. The advantage of a /proc/bus/isa is
that you can add ISA PnP (yuk) device identifation later (cfr. the other
/proc/bus/ drivers).
Or make them real memory devices (char major 1): /dev/isa_io and /dev/isa_mem?
What do you think?
Greetings,
Geert
--
Geert Uytterhoeven Geert.Uytterhoeven@cs.kuleuven.ac.be
Wavelets, Linux/{m68k~Amiga,PPC~CHRP} http://www.cs.kuleuven.ac.be/~geert/
Department of Computer Science -- Katholieke Universiteit Leuven -- Belgium
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