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Message-ID: <4B4DFF04.2070109@googlemail.com>
Date: Wed, 13 Jan 2010 18:12:36 +0100
From: =?ISO-8859-1?Q?Ren=E9_Bolldorf?= <xsecute@googlemail.com>
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To: Stefan Richter <stefanr@s5r6.in-berlin.de>
CC: Tilman Schmidt <tilman@imap.cc>,
       Henrique de Moraes Holschuh <hmh@hmh.eng.br>,
       linux-kernel@vger.kernel.org
Subject: Re: [Question]  For what stand's __initdata, __devinit etc. ?
References: <4B4CAA49.4090707@googlemail.com> <20100112234228.GA21777@khazad-dum.debian.net> <4B4DB0E3.9020707@imap.cc> <4B4DF6B1.406@s5r6.in-berlin.de>
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On 01/13/10 17:37, Stefan Richter wrote:
> Tilman Schmidt wrote:
>> Am 2010-01-13 00:42 schrieb Henrique de Moraes Holschuh:
>>> On Tue, 12 Jan 2010, Ren? Bolldorf wrote:
>>>> Hi,
>>>> Do we really need this?
>>>> It will be nice if someone can me explain this.
>>>
>>> http://kernelnewbies.org/FAQ/InitExitMacros
>>
>> That's far from complete. It does not, for example, mention __devinit.
>
> This wiki contains also somewhat misleadingly worded text:  "But why
> must you use these macros ?"  This should read:  "But why would you want
> to use these macros?"
>
> Answer:  They are a micro-optimization which allows the kernel to free
> memory that was occupied by this code at some point, because that code
> won't be used after that point anymore.  (In case of exit macros:  These
> are hints to discard some code from a build in case of certain kernel
> configurations.)  These macros only affect code which is statically
> linked into the kernel.
>
> Some macros, like for example __devinit, have so obscure uses and
> marginal benefits that a normal developer should not bother about them.
> __devinit in particular does not have any effect at all --- except if
> CONFIG_HOTPLUG is not defined.  This may happen in configurations for
> embedded systems.  But the majority of device drivers that you can find
> in the kernel tree are irrelevant (i.e. configured off) on such systems
> anyway.
>
> Some more information on these macros can be found in Corbet, Rubini,
> Kroah-Hartman: Linux Device Drivers, 3rd edition a.k.a. LDD3, which is
> also gratis available on the Web.

Thanks @all :-)
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