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Date: Wed, 16 Apr 1997 23:54:26 -0700 (PDT)
From: Dmitry Kohmanyuk <dk@dog.farm.org>
Message-Id: <199704170654.XAA10996@dog.farm.org>
To: brett@lariat.org (Brett Glass)
Cc: freebsd-hardware@freebsd.org
Subject: Re: talk to I/O Devices.
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In article <3.0.32.19970416104604.006b0dc4@lariat.org> you wrote:
> At 07:53 AM 4/16/97 -0600, jmg@hydrogen.nike.efn.org wrote:
>  
> >this is relativily easy...  all you need to do is open the /dev/io file...

> 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.