Message-ID: <4C5065B0.8060303@windriver.com>
Date: Wed, 28 Jul 2010 12:15:28 -0500
From: Jason Wessel <jason.wessel@windriver.com>
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To: Frederic Weisbecker <fweisbec@gmail.com>
CC: "Deng, Dongdong" <dongdong.deng@windriver.com>, will.deacon@arm.com,
        lethal@linux-sh.org, mahesh@linux.vnet.ibm.com,
        prasad@linux.vnet.ibm.com, benh@kernel.crashing.org, paulus@samba.org,
        mingo@elte.hu, kgdb-bugreport@lists.sourceforge.net,
        linux-kernel@vger.kernel.org
Subject: Re: [RFC PATCH] hw-breakpoints, kgdb, x86: add a flagtopassDIE_DEBUG
 notification
References: <1279851361-32604-1-git-send-email-dongdong.deng@windriver.com> <20100723130430.GA5255@nowhere> <4C4996FA.2010301@windriver.com> <20100723140745.GB5255@nowhere> <4C49BA00.5030200@windriver.com> <20100723161746.GD5255@nowhere> <4C4D6DD3.80909@windriver.com> <20100728170854.GC5394@nowhere>
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On 07/28/2010 12:08 PM, Frederic Weisbecker wrote:
> On Mon, Jul 26, 2010 at 07:13:23PM +0800, DDD wrote:
>   
>> Frederic Weisbecker wrote:
>>     
>>> Why? It seems to me a kernel debugger should have the highest priority
>>> over anything.
>>>       
>> In my option, the reason of kgdb set the lowest-prio for
>> notifier is:
>>
>> For letting kgdb to keep simple, there is no codes to check the
>> breakpoint event was generated by kgdb or not, thus it have to set kgdb
>> as lowest priority to notifier.
>>
>> If the breakpoint event is not generated by kgdb, the source of the
>> breakpoint event will consume that event before passing to kgdb's
>> routine, so that the breakpoint event of kgdb getting must be generated  
>> by kgdb itself.
>>     
>
>
>
> Ok, but that makes it hard to differentiate from a spurious breakpoint
> event.
>
>
>
>   

The original thinking was that if you are using a low level debugger
that you would want to stop on such a event or breakpoint because there
is nothing else handling it and your system is about to print an oops
message.


Jason.
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