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

[Marius Strobl]

On Wed, Jan 25, 2012 at 11:28:51AM +0100, Denny Schierz wrote:
> hi,
> 
> Am 24.01.2012 um 21:21 schrieb 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.
> 
> 
> hmm, all debug  options are active and  I send the break signal from ALOM, but I think, that FreeBSD isn't configured to interpret the signal. Can I enter the kdb first (sysctl debug.kdb.enter=1) and than execute "jail -r 1" ?
> 

Not that I'm aware of. Do you have a kernel built with options
BREAK_TO_DEBUGGER? Does it work when the machine doesn't hang
(you can resume via the "continue" command in the kernel
debugger)? Do you send the break via the "break" command of the
ALOM or by sending a break via a terminal attached to the ALOM
console?

Marius