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Subject: RE: How to go about debuging a system lockup?
Date: Thu, 16 Nov 2006 16:01:03 -0600
Message-ID: <19D0D50E9B1D0A40A9F0323DBFA04ACC023B0D87@USRV-EXCH4.na.uis.unisys.com>
Thread-Topic: How to go about debuging a system lockup?
Thread-Index: AccJyrVgcshUufYbSgSl4HvsedN+pQ==
From: "Protasevich, Natalie" <Natalie.Protasevich@UNISYS.com>
To: "Lennart Sorensen" <lsorense@csclub.uwaterloo.ca>,
       "Jesper Juhl" <jesper.juhl@gmail.com>
Cc: <linux-kernel@vger.kernel.org>
Sender: linux-kernel-owner@vger.kernel.org
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> I don't know of a good version yet.  I so far don't know if there ever
> was one.  This could even be a bug in the PCI hardware, or the way the
> BIOS on this system on a board configured the PCI controller.  Maybe I
> should go back and try a 2.4 kernel.
> 
> > Hope some of that helps :)
> 
> Well hopefully.
> 

If you can't drop in kdb, or no sysreq, then your interrupts are
disabled. I used to be (with older systems anyway) that NMI button was
on the system, so one could send an NMI and make the handler to print a
trace. Newer systems might not have that, so you can built your own PCI
card to send an NMI :)
Another possibility is to use port 80 and make suspicious code print
something to it. Once we used a small self-built thing with LEDs to
catch the output to the parallel port while debugging silent boot
failure. There are some port 80 cards that you can buy:
http://auctions.yahoo.com/i:Port%2080%20Card%20and%20power%20supply%20te
ster:102201489
http://www.amazon.com/gp/product/B000234U3I/ref=pd_cp_e_title/103-887558
8-5330221

If your system has a jtag then in target probe would be useful if you
have one (or can borrow one, those are expensive).

--Natalie

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