Re: [Xen-devel] How to generate a HW NMI

[Konrad Rzeszutek Wilk <konrad.wilk@xxxxxxxxxx>]

On Thu, Sep 30, 2010 at 12:59:25PM -0500, Roger Cruz wrote:
> 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

Nice.

> 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

What about the Mini PCI-e to PCI-e adapter:
http://www.hwtools.net/adapter/PM2C.html

And then plug in a PCI to PCI-e adapter:

http://www.newegg.com/Product/Product.aspx?Item=N82E16815158165&nm_mc=OTC-Froogle&cm_mmc=OTC-Froogle-_-Add-On+Cards-_-STARTECH-_-15158165

And then assert the SERR#?

> 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

Per this slide deck:
http://www.pcisig.com/developers/main/training_materials/get_document?doc_id=cdf593816ee20b90d8603d4aeb081a726ddc3091
it looks as if you can program the PCIe bridge to fall to "legacy" mode.

And per some folks post:
http://forums.gentoo.org/viewtopic-t-752165.html

it looks as if the SERR# signal is asserted on SMBus controller?
Maybe there is a way to do it via that?

> signal.  The platform is a Lenovo T500 laptop so the number of
> connectors to play with is limited.
> 

IBM on the server sides used to have NMI buttons - it could be that Lenova
hadn't completly gotten rid of them. Since you are open to looking at the
motherboard, maybe there is a spot marked #NMI ?

> 
>  
> 
> 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

How about just shorting the pins randomly :-)

> 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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