[pups] Stray Interupts

Steven M. Schultz sms at moe.2bsd.com
Mon Feb 26 04:48:51 AEST 2001

> From: Robin Birch <robin at ruffnready.co.uk>
> Having got to the point where I can get ultrix trying to boot on p11 I
> can confirm that it complains of stray interrupts on p11 as well.  A
> thought occurred to me over the weekend that I haven't had time to try
> out.  Is this the toy clock.  It is certainly built into p11, is it
> built into Bob Supnik's emulator and if so, does it generate interrupts?
	As Billy pointed out the TOY clock does not generate interrupts.  The
	line frequency clock does but the TOY clock does not.

	Looking at the Ultrix-3.1 sources I found something that may be
	relevant in sys/errlog.c:

 * Log a stray device interrupt.
 * A stray interrupt is defined as one that occurs for
 * a configured device through a valid vector address,
 * but is unexpected. In the case of big disks, a stray
 * interrupt is logged when the interrupt service routine
 * is entered and the device is not active and no attention
 * summary bits are set.

	One guess is that other systems do not use or concern themselves with
	'attention summary' bits and simply dismiss the interrupt without

	Looking at the errlogs (I do not know what the commands for doing that
	are but a big of digging would probably find them) might yield more


	Steven  Schultz
	sms at moe.2bsd.com

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