From owner-freebsd-questions  Wed May 31 10:47:27 2000
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From: Mac <mac@ngo.org.uk>
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Subject: Writing a value to an IO (mem mapped) port
To: freebsd-questions@freebsd.org
Date: Wed, 31 May 2000 18:47:35 +0100 (BST)
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Hi all,

Basically, I have a simple IO card installed in my PC and I control it
by writing to a (fixed I/O) port.

Under QBASIC I'd use:-

	OUT(&H181,0)

and under Visual C I use something like:-

	_outp(0x181,0)


However under FreeBSD, although the function seems to exist to do this
in /usr/include/machine/cpufunc.h, I get Bus Errors every time I try.

fred.c looks like this:-

	#include <sys/types.h>
	#include <machine/cpufunc.h>

	main()
	{
	 outb(0x181,0)
	}

And compiles OKay.

I'm assuming I'm missing something fairly fundamental here.  I've done
all my testing whilst logged in as 'root' on a 3.2-RELEASE box.
(without the actusl card installed just yet).


Any ideas?  (The core dump shows the Bus Error (signal 10) as occuring
in outbv() )




                       Mac


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