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Date: Sat, 27 Jul 1996 00:23:26 +0200 (MET DST)
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From: Stefan Esser <se@zpr.uni-koeln.de>
To: dg@root.com
Subject: Re: ncr53c810 driver in stable/current 
Cc: current@freebsd.org, stable@freebsd.org,
        "Marc G. Fournier" <scrappy@ki.net>
In-Reply-To: <199607220803.BAA10665@root.com>
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	<199607220803.BAA10665@root.com>
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David Greenman writes:

 > >	The last time I reported this, someone made mention that 
 > >the cause was the NCR driver not switching modes or something like 
 > >that, so that it can't dump core...?  
 > >
 > >	If anyone remembers this thread, or knows what the hell I'm
 > >talking about...has this been fixed in -current?
 > 
 >    We've seen this problem on freefall (which uses the NCR controller). It
 > likes to hang when we try to reboot it. I don't recall any fixes for this,
 > and I don't know what causes it.

Hmmm, it hangs when you try to reboot it ?

This is more probably related to some problem 
with the motherboard than the SCSI controller.
(Ie. the (in)famous BROKEN_KEYBOARD_RESET.)


But I now know how to make the NCR write a 
kernel dump in case of a crash:

 Just leave alone the "hole" between 0xe8000
 and 0xfffff ...

It seems that the NCR gets some error accessing 
this addresses. I did not have time to completely
analyse the resulting chip status, but it appears
that the failed memory access (which is reported 
to a PCI bus-master on a PCI bus line !) causes 
the hang.

Isn't it dangerous to touch that region from the
dump code, anyway ?

There might be memory mapped registers that make
some device change state when read ...

I will try to make the driver ignore the access
error in the dump, but it might be a good idea 
to not include the BIOS region in the dump (???)

Regards, STefan