Date: Tue, 9 Nov 1999 17:27:45 -0500 From: Greg Lehey <grog@mojave.sitaranetworks.com> To: Zhihui Zhang <zzhang@cs.binghamton.edu>, archie@whistle.com Cc: freebsd-hackers@FreeBSD.ORG Subject: Re: How to use gdb to catch a panic Message-ID: <19991109172745.27205@mojave.sitaranetworks.com> In-Reply-To: <Pine.GSO.3.96.991109160106.10533C-100000@sol.cs.binghamton.edu>; from Zhihui Zhang on Tue, Nov 09, 1999 at 04:04:34PM -0500 References: <19991109164507.31840@mojave.sitaranetworks.com> <Pine.GSO.3.96.991109160106.10533C-100000@sol.cs.binghamton.edu>
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On Tuesday, 9 November 1999 at 16:04:34 -0500, Zhihui Zhang wrote:
> On Tue, 9 Nov 1999, Greg Lehey wrote:
>> On Tuesday, 9 November 1999 at 13:36:56 -0800, Archie Cobbs wrote:
>>> Zhihui Zhang writes:
>>>> Thanks for your reply. What confuses me is that when I use commands "gdb"
>>>> (enter remote protocol mode) and "step" on the target machine, the
>>>> debugging machine takes control (it executes "target remote /dev/cuaa1").
>>>> In this case, how can I run anything on the target machine to trigger a
>>>> panic?
>>>
>>> I'm not sure if this answers your question, but the command
>>>
>>> sysctl -w debug.cebugger=1
>>>
>>> will cause the kernel to stop and return your gdb prompt.
>>> Then you could call the function panic() directly if you wanted.
>>
>> Take a look at /usr/src/sys/modules/vinum/.gdbinit.kernel. There's
>> some almost undocumented stuff in there, including a macro called
>> ddb. Call it from gdb and it'll switch back to ddb.
>
> Thanks! I will certainly look into them. In the same time, I add a
> sysctl variable and let my program calls Debugger("some string") if that
> sysctl variable is true.
I don't understand what that's useful for.
> It seems working. I hope someone will write a hacker's book.
I'm intending to write something on the subject, but don't count on it
soon.
Greg
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