Howto debug Kernel problems ? (jail -r -> freeze)

[Marius Strobl]

On Mon, Jan 23, 2012 at 01:16:22PM +0100, Denny Schierz wrote:
> hi,
> 
> If I stop a jail (v2 with vnet), the jail doesn't completely disappear. "jls" shows the jail as active. If I try to remove the jail with "jail -r <id>" the whole machine freezes. Other users with same options (i386) doesn't have this problem. So how can I debug it?
> 

I'd start with a kernel built with BREAK_TO_DEBUGGER, DDB and KDB
enabled. Then when it appears to hang try to break into the debugger
by sending a break on the serial console. If that works try to bug
virtualization@ and probably bz@ directly for information they
want as given that you mention vnet it sounds like you're not
seeing this problem without VIMAGE.

Marius