RE: How to go about debuging a system lockup?

["Protasevich, Natalie" <Natalie.Protasevich@UNISYS.com>]

> 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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