Serious flaws in SCO's serial device driver for XENIX (SIO)

Harald Milne harald at boink.UUCP
Fri Dec 14 21:37:10 AEST 1990

     While I'm here, I might as well let everybody know about this.

	 For a year now, my XENIX continiously crashed with panic TRAP D.

	 Also, any program would randomly drop core and die. So you can see, I
had a very flaky and unreliable system. I was begining to think XENIX was
just plain garbage.

	 2 months now, since replacing SIO with FAS, ALL these problems have

	 I'm using a dumb serial card with 2 16550's. Originally, I had 16450's.
I even turned on the FIFO's before eventually installing FAS. Nothing helped,
until I ripped out SIO, and put in FAS.

	 Conclusion: SIO is broken, and broken bad enough to crash your system.
				 Don't use SIO with dumb serial cards.

	 I've been running Bnews 2.11.19 via UUCP at 2400 baud for over a year,
and now finally, my system is working like it should. I spent MANY hours
trying to fix this problem (like writing a replacement driver).

	 SCO should be shot for this problem. Kernel panics are serious!

PS: I only changed a few ints to longs in FAS 2.07, for use on the 286.

PPS: I had to DROP the priority from 7 to 5 (same as the hard disk) to keep
     serial activity from overwelming the hard disk!!! The highest hardware
	 priority is now the clock device.  (As it should be on sane unix systems.)
Harald Milne                   RISCy business	       uunet!ccicpg!boink!harald

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