linux-kernel - Re: [PATCH 07/14] mce3: pass mce info to EDAC for decoding

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Date:	Mon, 20 Jul 2009 13:17:54 -0700
From:	"H. Peter Anvin" <hpa@...or.com>
To:	Andi Kleen <andi@...stfloor.org>
CC:	Doug Thompson <norsk5@...oo.com>,
	Borislav Petkov <borislav.petkov@....com>, mingo@...e.hu,
	tglx@...utronix.de, aris@...hat.com, linux-kernel@...r.kernel.org,
	x86@...nel.org
Subject: Re: [PATCH 07/14] mce3: pass mce info to EDAC for decoding

Andi Kleen wrote:
>> The goal is to have a default handler within the kernel and a more specific handler in a module after it has loaded. Using the weak symbol as a mechanism to do that. I haven't used that, so I don't know if it works.
> 
> weak symbols don't work over kernel modules.
> 

For modules, you typically have to have a callback to update an internal
function pointer.  If you think about it, it's pretty obvious -- a weak
symbol changes the behavior at link time, but it's still a static call.
 If you want modules to change the behavior, you're talking about a
*dynamic* change -- the call will point to different things at different
points in time -- so you need another mechanism, i.e. function pointers.

	-hpa

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