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To: Kazutaka YOKOTA <yokota@zodiac.mech.utsunomiya-u.ac.jp>
cc: freebsd-hackers@freebsd.org, freebsd-bugs@freebsd.org
Subject: Re: trap type 29 on P6 
In-reply-to: Your message of "Tue, 20 May 1997 12:11:21 +0900."
             <199705200311.MAA17969@zodiac.mech.utsunomiya-u.ac.jp> 
From: David Greenman <dg@root.com>
Reply-To: dg@root.com
Date: Mon, 19 May 1997 20:17:21 -0700
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>>>>     kernel: type 29 trap, code=0
>>>>     Stopped at      _read_kbd_data_no_wait+0x37:    andl    $0xff,%eax
>>
>>   Is the instruction right before this one an inb or outb? I've seen this
>>before on P6 machines...
>
>Exactly!!. We have:
>
>	movl (%ebx),%edx
>	inb %dx,%al
>	andl $255,%eax
>
>It's reading the port 0x60 for keyboard data.

   Yeah, I think this is either a flaw in the P6 or in the motherboard
chipset. I believe it's telling you that it detected a parity error during
the PIO instruction. Wcarchive used to crash every day or two from this
occuring while doing PIO in the ahc driver until Justin added support
for doing memory mapped register accesses.

-DG

David Greenman
Core-team/Principal Architect, The FreeBSD Project