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Date:      Thu, 28 May 2009 23:04:29 -0700
From:      Kip Macy <kmacy@freebsd.org>
To:        David N <davidn04@gmail.com>
Cc:        freebsd-hackers@freebsd.org
Subject:   Re: Debugging via DDB
Message-ID:  <3c1674c90905282304s223349c4p8523abbbed8ade0b@mail.gmail.com>
In-Reply-To: <4d7dd86f0905282127u5215979akdd8ea286c73f090e@mail.gmail.com>
References:  <4d7dd86f0905282127u5215979akdd8ea286c73f090e@mail.gmail.com>

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On Thu, May 28, 2009 at 9:27 PM, David N <davidn04@gmail.com> wrote:
> Hi,
>
> I know this might sound like a newbie question.
>
> I'm trying to debug a "Lockup" on 7.2-RELEASE. I've compiled DDB and
> KDB into the kernel and make installkernel. (Can this be called a
> deadlock?)
>
> The machine still response to pings, but it looks like all disk
> activity has stopped.
>
> I can break into the debugger using CTRL-ALT-ESC, but after that, i
> dont know what I'm looking for in particular.
>
> bt (backtrace) gives me the stuff like the keyboard mutex ( i assume
> it was the last thing that happened, but obviously it was the break)
>
> Should I be including WITNESS?

Include WITNESS.  "ps" to list processes, "show proc" to see proc
info, "thread <no>" to switch to a thread, "show locks" to see locks
held, show sleepc to see what you're blocked on (if a sleepq), and
"show alllocks" to see all locks held
-Kip



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