On Mon, 22 Apr 2002, Geert Uytterhoeven wrote: > > Hmm, I admit I haven't looked at this matter, but aren't > > in/out/ioperm/iopl implemented as library functions in glibc like for > > other architectures doing MMIO? E.g. Alpha does this an it makes porting > > Perhaps. Note that you still need some /proc magic to find out the correct > address to map. Or you can use /dev/ports. Well, for Alpha ioperm/iopl functions check the system type in /proc/cpuinfo (we seem to have enough information there as well) and failing this they check a result of readlink of /etc/alpha_systype. Then an appropriate region of /dev/mem is mmapped with per-page permissions set up as requested if ioperm is used (with a worse granularity, though) and subsequent in/out function invocations access the area as appropriate. See sysdeps/unix/sysv/linux/alpha/ioperm.c in glibc for details -- it's a pretty clever solution with good performance and only a few trade-offs. -- + Maciej W. Rozycki, Technical University of Gdansk, Poland + +--------------------------------------------------------------+ + e-mail: macro@ds2.pg.gda.pl, PGP key available +
