Re: iopl on ALPHA

Richard Henderson (
Tue, 16 Dec 1997 01:04:43 -0800

On Mon, Dec 15, 1997 at 11:33:50PM +0000, linux-kernel subscriber wrote:
> I have some alpha patches, which don't use iopl, but just
> use ioperm, so the question is, how do IO permissions work
> on Alpha ? (More specifically, does iopl exist and do the
> same thing for alpha systems as x86).

As you guessed, ioperm/inb/outb/etc are done completely in userspace
on the Alpha. It is done by mmapping appropriate bits of /dev/mem
and doing minor magic with the sparse i/o space we find there.

We do not implement iopl, you must use ioperm with the appropriate
range of i/o ports.