linux-kernel - Re: [ANNOUNCE] Merkey's Kernel Debugger

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Message-ID: <2232.69.2.248.210.1218137662.squirrel@webmail.wolfmountaingroup.com>
Date:	Thu, 7 Aug 2008 13:34:22 -0600 (MDT)
From:	jmerkey@...fmountaingroup.com
To:	"Jay Lan" <jlan@....com>
Cc:	"Christoph Lameter" <cl@...ux-foundation.org>,
	"Stefan Richter" <stefanr@...6.in-berlin.de>,
	"Nick Piggin" <nickpiggin@...oo.com.au>,
	"Andi Kleen" <andi@...stfloor.org>, jmerkey@...fmountaingroup.com,
	"Geert Uytterhoeven" <geert@...ux-m68k.org>,
	"Josh Boyer" <jwboyer@...il.com>, linux-kernel@...r.kernel.org,
	"Takenori Nagano" <t-nagano@...jp.nec.com>,
	"Vivek Goyal" <vgoyal@...hat.com>,
	"Bernhard Walle" <bwalle@...e.de>, "Keith Owens" <kaos@....com.au>
Subject: Re: [ANNOUNCE] Merkey's Kernel Debugger

> 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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