Message-ID: <4A64D0F2.7050009@zytor.com>
Date: Mon, 20 Jul 2009 13:17:54 -0700
From: "H. Peter Anvin" <hpa@zytor.com>
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To: Andi Kleen <andi@firstfloor.org>
CC: Doug Thompson <norsk5@yahoo.com>,
       Borislav Petkov <borislav.petkov@amd.com>, mingo@elte.hu,
       tglx@linutronix.de, aris@redhat.com, linux-kernel@vger.kernel.org,
       x86@kernel.org
Subject: Re: [PATCH 07/14] mce3: pass mce info to EDAC for decoding
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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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