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From: Bill Fenner <fenner@parc.xerox.com>
To: bugs@freebsd.org
Subject: sio does outb(4,0) while trying to disable interrupts
Message-Id: <95Oct13.122057pdt.177475@crevenia.parc.xerox.com>
Date: Fri, 13 Oct 1995 12:20:54 PDT
Sender: owner-bugs@freebsd.org
Precedence: bulk

In sio's invasive attempt to disable interrupts on all potential serial
ports (which is the cause of the recent Mach64 complaints), it also
writes a 0 to port 4, which has nothing to do with any serial stuff
as far as I can tell.

likely_com_ports[] is 0 terminated, but the loop in sioprobe() uses
sizeof() instead of looking for a terminator.  Since the solution is
really to make this sequence non-destructive, I won't supply a diff,
but I thought that whoever is planning to fix the sio/mach64 problem
should be aware of this detail.

  Bill