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Date: Thu, 7 Aug 2008 13:34:22 -0600 (MDT)
Subject: Re: [ANNOUNCE] Merkey's Kernel Debugger
From: jmerkey@wolfmountaingroup.com
To: "Jay Lan" <jlan@sgi.com>
Cc: "Christoph Lameter" <cl@linux-foundation.org>,
       "Stefan Richter" <stefanr@s5r6.in-berlin.de>,
       "Nick Piggin" <nickpiggin@yahoo.com.au>,
       "Andi Kleen" <andi@firstfloor.org>, jmerkey@wolfmountaingroup.com,
       "Geert Uytterhoeven" <geert@linux-m68k.org>,
       "Josh Boyer" <jwboyer@gmail.com>, linux-kernel@vger.kernel.org,
       "Takenori Nagano" <t-nagano@ah.jp.nec.com>,
       "Vivek Goyal" <vgoyal@redhat.com>, "Bernhard Walle" <bwalle@suse.de>,
       "Keith Owens" <kaos@ocs.com.au>
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> Christoph Lameter wrote:
>> Stefan Richter wrote:
>>> Christoph Lameter wrote:
>>>> The competing implementation is kdb not kgdb. kgdb is just a stub for
>>>> remote
>>>> debugging using gdb. kdb is an in-kernel debugger like the one
>>>> proposed here.
>>> Is there work underway to get kdb merged?  (I'm just asking because I
>>> don't know; I personally don't need kdb nor mdb.)
>>
>> KDB still exists in patches but the merge effort was given up when Linus
>> stated that he did not want a kernel debugger. No problem to start merge
>> attempts again AFAICT. Jay?
>
> To merge KDB or any other RAS tools, you need to deal with kdump. Kdump
> hijack panic() before the die calling chain. For KDB or a RAS tool to
> work, an infrastructure such as the "add new notifier function" by
> Takenori Nagano should be in place.
>
> His last attempt fell short, in my opinion, was partly due to his
> "[PATCH 3/3] Move crash_kexec() into  panic_notifier" did not do what it
> meant to do: to fit kexec/kdump into the new infrastructure. That is
> not fatal; it can be fixed to make it right. If community is interested
> in getting a kernel debugger to the kernel, we can continue Takenori's
> work. Once the infrastructure is accepted, then merging KDB or any other
> kernel debugger will make sense.
>
> Regards,
>  - jay
>
>
>>

As I look through entry_32.S and traps_32.c I do not see where kdump is
hooking the notify_die handler which would intercept calls to a debugger.

Where does kdump hook this path?

Jeff


>
>


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