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From: ptuomola@hacktic.nl (Petri Tuomola)
Newsgroups: comp.os.386bsd.questions
Subject: The reason for stray interrupts
Date: 26 Oct 1993 10:56:50 +0100
Organization: Hack-Tic, networking for the masses
Lines: 42
Message-ID: <2ais9gINN2t8@xs4all.hacktic.nl>
NNTP-Posting-Host: xs4all.hacktic.nl
Many people have been asking why their machines display "ISA strayintr 7"
messages. This is an extract from /sys/arch/i386/isa/isa.c:
/* for some reason, we get bursts of intr #7, even if not enabled! */
/*
* Well the reason you got bursts of intr #7 is because someone
* raised an interrupt line and dropped it before the 8259 could
* prioritize it. This is documented in the intel data book. This
* means you have BAD hardware! I have changed this so that only
* the first 5 get logged, then it quits logging them, and puts
* out a special message. rgrimes 3/25/1993
This is of course nothing new, I just thought it would be nice to tell those
who don't know this yet. I couldn't find this from FAQ although I definitely
think it should be there - I have seen at least 5 messages asking for this
within one week.
BTW. My experience is that they cause no harm, except the very small extra
system load caused by stray interrupts getting handled (you can't notice the
difference). I get stray interrupts with a "steady rate":
interrupt count rate
stray irq 2985 1 <--
clk irq0 179836 100
wdc0 irq14 84551 47
fdc0 irq6 1 0
sc0 irq1 5006 2
com0 irq4 56583 31
com2 irq9 2985 1
Total 331947 184
And I have noticed no problems because of them - no lockups, nothing. If someone
has different experiences I would be interested to hear.
Petri
--
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Petri Tuomola (root@echelon.hacktic.nl) (ptuomola@hacktic.nl)
"Get stoned - eat wet concrete" HAM: OH2LJY