Please help me diagnose this crazy VMWare/FreeBSD 8.x crash

John Baldwin jhb at
Thu May 31 15:58:04 UTC 2012

On Thursday, May 31, 2012 11:11:11 am Mark Felder wrote:
> So when this hang happens, there never is a real panic. It just sits in a  
> state which I describe as like being in a deadlock. How would I go about  
> getting a crashdump if it never panics? Is it possible to do the dump over  
> a network or something because I don't believe it can write through the  
> controller at all.

You can break into ddb and run 'call doadump'.  It should use polled IO, so 
there is a slight chance of it working.

> Also, thank you for the KTR_SCHED tip. This is the type of info I was  
> looking for. Unfortunately I've only ever seen this crash once on a kernel  
> with debugging enabled. The machine which is currently prepared to do this  
> work used to crash a few times a week and now it has 70 days uptime...  
> however, it is an example of a machine with mpt0 and em0 sharing an IRQ so  
> I might be able to trigger it using Dane's method.
> $ vmstat -i
> interrupt                          total       rate
> irq1: atkbd0                         392          0
> irq6: fdc0                             9          0
> irq14: ata0                           34          0
> irq18: em0 mpt0               1189748491        218
> cpu0: timer                   2174263198        400
> Total                         3364012124        619
> I'm doing my best to get you guys the info you need, but this is one heck  
> of a Heisenbug...


John Baldwin

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