Gathering Hardware State During a Driver Initiated Kernel Panic

Sam Leffler sam at
Mon Nov 24 14:14:18 PST 2008

David Christensen wrote:
> Is there a method or callback in FreeBSD where a driver can 
> be notified that it has caused a kernel panic in order to 
> generate a dump of internal hardware state information?  I've
> written a sysctl call for manual intervention and can handle
> some "expected" hardware events completely in the driver but
> I don't know of a way to get control again in cases where the 
> driver wasn't expecting a failure.

Not sure how one can deduce a driver is at fault but you might define a 
ddb command for the driver and invoke that on panic using the ddb script 
mechanisms (see ddb(4)).


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