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Date:      Mon, 13 Mar 1995 13:48:18 -0800 (PST)
From:      Jack Valko <>
Subject:   i/o interrupts
Message-ID:  <>

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We're having a perplexing problem with I/O and FreeBSD 2.0 (not the
February release).  We have the FreeBSD box (486, 33mhz, 8megs RAM) and an
I/O board sending a continuous stream of data to COM1 (/dev/tty00).  It
seems that interrupts are building in a buffer if they are not handled
fast enough.  Instead of the buffer overflowing or interrupts being lost,
the tty interfaces lock, but the system continues to function (for
example, httpd still runs).  As soon as we kill the program(s) that are
sending and receiving data thru tty00, or we disconnect the external I/O
source the ttys free up. 

We use fopen("/dev/tty00", "r+") to move data to and from the port.  

Any ideas??

Jack Valko					  

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