Date: Thu, 17 Apr 1997 09:21:03 -0600 From: Brett Glass <brett@lariat.org> To: dk+@ua.net Cc: freebsd-hardware@freebsd.org Subject: Re: talk to I/O Devices. Message-ID: <3.0.1.32.19970417092103.0070f97c@lariat.org> In-Reply-To: <199704170654.XAA10996@dog.farm.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
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