>From: Operator <oper@mikrobitti.fi>
>Date: Wed, 22 May 1996 11:33:16 +0300 (EET DST)

>A friend of mine is trying to get a DigiBoard serial card working on
>NetBSD.  He would like to peek the UART registers to see what is going
>on with them.
>
>Is it possible to use /dev/io to read (and write?) i386 IO space
>registers?  If so, how?

First: AFAIK, use of /dev/io is discouraged; you should use the
functions (e.g. ioperm()) in libi386.a instead.

/dev/io is similar to /dev/mem, except that it accesses the x86 I/O
space instead of memory.  To use /dev/io, use something like:

#include <unistd.h>

int inb(addr)
    unsigned addr;
{
    int fd;
    char data;

    fd = open("/dev/io", O_RDONLY);
    lseek(fd, (off_t)addr, SEEK_SET);
    read(fd, &data, 1);
    close(fd);
    return (int)data;
}

...preferably something that checks syscall return values. :-)
-- 
Mike Long <mike.long@analog.com>     <URL:http://www.shore.net/~mikel>
VLSI Design Engineer         finger mikel@shore.net for PGP public key
Analog Devices, CPD Division          CCBF225E7D3F7ECB2C8F7ABB15D9BE7B
Norwood, MA 02062 USA       (eq (opinion 'ADI) (opinion 'mike)) -> nil