Freebsd assembly programming - IN/OUT commands.

[Peter Pentchev]

On Sun, Oct 17, 2004 at 04:00:57PM +0300, Giorgos Keramidas wrote:
> On 2004-10-16 14:03, Jan Opacki <opacki at acn.waw.pl> wrote:
> > I had a short look at your fbd assembly tutorial. I'm have a such
> > problem useing IN, OUT commands. In my case i want to "speak" with cmos
> > by port 70 and 71. We both know that fbsd as same as linux works in safe
> > mode. So we need a permission to use each port. In linux it's a system
> > call sys_ioperm (http://www.die.net/doc/linux/man/man2/ioperm.2.html).
> > How to ask FreeBSD to allow us to use those ports ? And then we could
> > simply do:
> >         mov al, 0
> >         out 70h, al
> >         nop
> >         nop
> >         nop
> >         nop
> >         in al, 71h
> > Do you haveny any idea ?
> 
> Look at the io(4) manpage.  You need superuser access to work with
> /dev/io and even then your program should be very careful about not
> messing up badly with the hardware, but I think it does what you need.

Of course, a bit more controlled way (as described in the io(4) manpage,
too), would be to use the i386_set_ioperm(2) syscall :)  It is a bit
non-portable, true, but since Jan uses MASM-style assembly and mentions
ports 70h and 71h, I think it would do what he needs.

G'luck,
Peter

-- 
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