Date: Thu, 1 Jun 2000 13:44:14 +0100 From: Ben Smithurst <ben@scientia.demon.co.uk> To: Mac <mac@ngo.org.uk> Cc: freebsd-questions@freebsd.org Subject: Re: Writing a value to an IO (mem mapped) port Message-ID: <20000601134414.U99925@strontium.scientia.demon.co.uk> In-Reply-To: <200006010857.JAA20643@ngo.org.uk> References: <20000531192931.Q99925@strontium.scientia.demon.co.uk> <200006010857.JAA20643@ngo.org.uk>
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Mac wrote:
> I can't get i386_{set,get}_ioperm to work. All attempts at calling these functions
> result in a return value of -1 (errno=22 (EINVAL)).
>
>
> Code I'm using looks like this:-
>
> #include <errno.h>
> #include <machine/sysarch.h>
>
> main()
> {
> unsigned int port;
> unsigned int *length;
> int *enable;
>
> int res;
>
> port = 0x180;
>
> res = i386_get_ioperm(port,length,enable);
First, you're passing uninitialized pointers to i386_get_ioperm()
(length and enable). You shouldn't declare them as pointers, then you
pass their address (e.g. with &enable) in the ioperm call. But even
after changing that, it still fails. As I said, I've never used this
function, and I guess it shows. :-)
I think another way is to open /dev/io before doing your outb. As long
as you have /dev/io open (you don't need to read or write anything
to it) your process is allowed direct IO access, AFAIK. I think
i386_set_ioperm is the newer method though, so hopefully someone who has
used it can explain how it's done.
Aha! I think I see why, after reading the source. It appears you'll
need 'options VM86' in your kernel config for these to work. The manual
page should probably tell you this. If it still doesn't work then, I
don't know.
--
Ben Smithurst / ben@scientia.demon.co.uk / PGP: 0x99392F7D
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