linux-kernel - Re: [Patch-next] Remove notify_die in do_machine

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Message-ID: <4BFE17E1.7020103@linux.intel.com>
Date:	Thu, 27 May 2010 08:57:37 +0200
From:	Andi Kleen <ak@...ux.intel.com>
To:	Hidetoshi Seto <seto.hidetoshi@...fujitsu.com>
CC:	Huang Ying <ying.huang@...el.com>,
	Jin Dongming <jin.dongming@...css.fujitsu.com>,
	LKLM <linux-kernel@...r.kernel.org>
Subject: Re: [Patch-next] Remove notify_die in do_machine_check functioin

, Hidetoshi Seto wrote:
> (2010/05/27 12:21), Huang Ying wrote:
>> I have heard about that on some machine, some hardware error output pin
>> of chipset may be linked with some input pin of CPU which can cause MCE.
>> That is, MCE is used to report some chipset errors too. I think that is
>> why notify_die is called in do_machine_check. Simply removing notify_die
>> is not good for these machines.
>
> Hum, it sounds like "notify_die here is hook for proprietary chipset
> driver".  Anyone who have such machine and driver in real?

No, the die hook was to be compatible with the old KDB patchkit
which hooked into MCE too.

> Problems are (1) many callbacks will behave wrongly since they don't
> aware that DIE_NMI event can be posted from Machine Check, and (2)
> if the machine is not such special hardware it is just waste of time
> in critical context where quick page-poisoning might be required.

Yes the best action is probably to just remove it right now.

> One quick alternative is define "DIE_MCE" and use it instead, but
> if special hook like this is really required, I suppose we should
> invent some special interface for external plug-in like a chipset's
> LLHEH (low-level hardware error handler) etc., to allow additional
> platform-specific error handling in critical context.

I don't think we need or want that.

-Andi


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