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Date: Tue, 17 Aug 2010 14:03:04 +0800
From: Li Zefan <lizf@cn.fujitsu.com>
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To: Frederic Weisbecker <fweisbec@gmail.com>
CC: Ingo Molnar <mingo@elte.hu>, Heiko Carstens <heiko.carstens@de.ibm.com>,
        Martin Schwidefsky <schwidefsky@de.ibm.com>,
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        Peter Zijlstra <a.p.zijlstra@chello.nl>,
        Thomas Gleixner <tglx@linutronix.de>, Don Zickus <dzickus@redhat.com>
Subject: Re: [PATCH] lockup_detector: Make DETECT_HUNT_TASK default depend
 on LOCKUP_DETECTOR
References: <4C58C7FF.5060906@cn.fujitsu.com> <20100806005801.GB5436@nowhere> <20100807070135.GC23108@elte.hu> <20100808195839.GA5387@nowhere>
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(Just came back from vacation)

>> Maybe a better change would be to make it more generally available - right now 
>> it's:
>>
>>  config LOCKUP_DETECTOR
>>          bool "Detect Hard and Soft Lockups"
>>          depends on DEBUG_KERNEL && !S390
>>
>> which means that it cannot be enabled when DEBUG_KERNEL is off.
>>
>> So i think we should:
>>
>>  - Remove the s390 hack and add an ARCH_HAS_LOCKUP_DETECTOR flag
> 
> If we do this, we'll need to add this config on every archs but s390.
> We should better have ARCH_WANT_NO_LOCKUP_DETECTOR. I know that
> "negative" meaning configs suck, but otherwise we would lose this
> support on many archs.
> 
> Why s390 doesn't want the softlockup detector to begin with?
> 
>>  - Remove the DEBUG_KERNEL dependency
> 
> Yeah.
> 

Seems we haven't come to an agreement yet? I don't know much about the
lockup detector code, so please take care of this. :)