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

["Roger Cruz" <roger.cruz@xxxxxxxxxxxxxxxxxxx>]

Disabling SMIs is part of the experiments to be conducted today or  
tomorrow.  I will keep u posted.



On Oct 12, 2010, at 4:48 AM, "Jan Kiszka" <jan.kiszka@xxxxxxxxxxx>  
wrote:
> Am 11.10.2010 23:20, Roger Cruz wrote:
> > Here is some additional info from my experiments over the weekend.
> >
> > I took the Lenovo T500 and removed its internal WiFi miniPCIe  
> > card.  In
> > its place, I put in a miniPCIe to PCIe converter card with a PCIe
> > socket.  Into that socket, I placed a PCIe dump card.  This card  
> > has a
> > switch that when you press it, it creates an SERR error.  Using the
> > utility provided by the vendor, I enabled all the bridges between the
> > card to carry the SERR signal to the CPU and cause the CPU to see  
> > it as
> > an NMI.  I tested the set-up several times.  Every single time I  
> > pressed
> > the switch, I got an NMI, followed by a kdump core.  So I was sure  
> > the
> > HW setup was working correctly.
> >
> > I left two Lenovo T500 running over the weekend and when I returned  
> > this
> > morning, both had hung.  Completely frozen.  I pressed the NMI  
> > switch in
> > both systems and nothing.  No crashes, no coredumps.  It looks as  
> > if the
> > SERR/NMI is getting ignored/blocked or CPU is completely shutdown
> > (STPCLK).
> >
> > This experiment helps me prove that the software watchdog code in Xen
> > was not the problem and indeed the NMIs are getting blocked somehow.
> > This is what I now need to investigate.  Areas that I care to learn  
> > more
> > about are the SMI handler and the external chip's use of the STPCLK
> > signal to the CPU.
> >
> > As an additional bit of info, the only response we get when the  
> > systems
> > are hung is a beep when the power cord is unplugged/plugged from the
> > laptop.  I don't know if the beep is done via a HW module or whether
> > ACPI/BIOS is involved.
> >
> > Still looking for additional ideas.
> Already tried to disable SMIs?
>
> Jan
>
> --
> Siemens AG, Corporate Technology, CT T DE IT 1
> Corporate Competence Center Embedded Linux
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