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Date: Thu, 17 Apr 1997 09:21:03 -0600
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From: Brett Glass <brett@lariat.org>
Subject: Re: talk to I/O Devices.
Cc: freebsd-hardware@freebsd.org
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At 11:54 PM 4/16/97 -0700, Dmitry Kohmanyuk wrote:
 
>> Fascinating. What does opening this "file" actually do? (I can't find it
>> in the source.)
>
>look at /sys/i386/i386/mem.c:mmopen() and others in that file.

Just looked at it, and it appears that this file opens the I/O space
as a random-access device. But accessing ports this way would slow
code down so dramatically that it could be useless for many
control applications! Also, the sample code in previous messages in
this thread seems to indicate that one can read and write directly.
How is this done?

--Brett