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[Xen-devel] How to generate a HW NMI

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Subject: [Xen-devel] How to generate a HW NMI
From: "Roger Cruz" <roger.cruz@xxxxxxxxxxxxxxxxxxx>
Date: Thu, 30 Sep 2010 12:59:25 -0500
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Thread-topic: How to generate a HW NMI

Hi fellow Xen developers,


I continue to get system hangs where the watchdog NMI in Xen is not doing its job.  I am completely blind as to what is getting jammed.  Tried multiple experiments to force the hang and in each, the watchdog has kicked in, so I know the mechanism works 99% of the time except in my one hang.


So in the old days of PCI bus, I used to be able to generate a HW NMI by asserting the SERR signal in the connector.  With the advent of PCIe, I believe that signal is no longer present, so I am looking for any other way to cause a system error.    I have examined the PCI express mini-card specification looking for a signal I can use in the internal WiFi connector, but alas, none of the signals I read about seem like they would do what I need.  I am not sure if there is anything I can short in the PCIe signals that could have a similar effect as the SERR signal.  The platform is a Lenovo T500 laptop so the number of connectors to play with is limited.


I also thought of causing a parity/ECC error but the GM45 chipset used in this laptop does not support ECC memory.


So I’m basically looking for any other ideas on how to cause a fault by probing somewhere in the motherboard.  This MB has a docking station connector but I have not been able to find the pinout list so I don’t know what is brought out there.  At this point, I have no problem cracking up the case and soldering something on to the motherboard.. I just need to know what chips and signals to tap.


Thanks in advance.


Roger R. Cruz

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