Re: iopl on ALPHA
Tue, 16 Dec 1997 06:29:12 +0100

On Mon, Dec 15, 1997 at 11:33:50PM +0000, linux-kernel subscriber wrote:

> I'm in the process of updating isapnptools, and just got rid
> of all references to ioperm because iopl is needed anyway on
> x86 systems and gives unrestricted port access.
> 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).
> Grepping the kernel sources shows nothing for ioperm or iopl
> for alpha systems, so I guess it's a C library thing. Would
> someone please tell me how IO works on Alpha systems, or
> point me in the right direction.

The same problem also hit's other platforms. Basically the problem
is that supporting ioperm/iopl on non-Intel platforms is suboptimal
in terms of performance. You should probably use /dev/port only
to handle this. The performance hit of /dev/port shouldn't matter
for this case.