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

Michael Powell nightrecon at
Thu Mar 29 07:53:43 UTC 2012

Mark Felder wrote:

> Alright guys, I'm at the end of my rope here. For those that haven't seen
> my previous emails here's the (not so) quick breakdown:
> Overview:
> FreeBSD ?? - 7.4 never crash
> FreeBSD 8.0 - 8.2 crashes
> FreeBSD 8-STABLE, 8.3, and 9.0 are untested (Sorry, not possible in our
> production at this time, and we were hoping we could base some stuff on
> 8.3 for long term stability...)
> ESXi: Confirmed ESXi 4.0 - 5.0 has this problem. Haven't tested on others.
> I think we've finally found enough data that this is definitely something
> in the FreeBSD world. I'm going to begin prepping some of the known crashy
> servers with more debugging. Any suggestions on what I should build the
> kernel with? They never do a proper panic, but I definitely want to at
> least *try* to get into the debugger the next time it crashes. And when it
> crashes, what the heck should I be running? I've never played with the KDB
> before...
> Thank you for any suggestions and help you can give me....

I am definitely out of my league here and this is way over my head, to be 
sure. Just a couple of shots in the dark for possibly covering a couple more 
data points for your research. And I am a tad fuzzy on both as I have never 
needed to dig into either because I've not had any trouble with either.

IIRC there are three different timer subsystems one may choose from. You may 
want to look into expirementation with each of the three, just to see if 
this changes any observed behaviors. Or to possibly rule it out. 

Your situation sounds like a candidate for reverse logic - if I can't get 
any handle on what's wrong I start at the opposite end and try to make a 
list of what is "right" in an attempt to leave a smaller subset to probe.

I also think this most likely has nothing to do with what's happening, but 
for some reason it just pops into my head. Try disabling msi in 
/boot/loader.conf like this:


At least if it makes no difference maybe this will exclude it from being a 
'possible'. Developers who are more in-depth aware of what the differences 
are between 7.x and 8.x/9.x in the development timeline can probably provide 
a better picture so as to narrow the field of what to look at. This is way 
over my head, just wish I could help - I know and have experienced the kind 
of quandary you have here (I feel for you).   :-)


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