Date: Tue, 7 Sep 2004 21:32:29 +0200
From: Adrian Bunk <bunk@fs.tum.de>
To: Krzysztof Halasa <khc@pm.waw.pl>
Cc: linux-kernel@vger.kernel.org
Subject: Re: unneeded #include <version.h> in many places ?
Message-ID: <20040907193229.GD2454@fs.tum.de>
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On Tue, Sep 07, 2004 at 06:17:53PM +0200, Krzysztof Halasa wrote:

> Hi,

Hi Krzysztof,

> I noticed some kernel .c files #include <version.h> which typically
> contains something like:
> 
> #define UTS_RELEASE "2.6.9-rc1"
> #define LINUX_VERSION_CODE 132617
> #define KERNEL_VERSION(a,b,c) (((a) << 16) + ((b) << 8) + (c))
> 
> However, those files don't reference the macros.
> 
> The question is: are these includes completely unneeded, so I can
> remove them, or do they serve some special purpose?

they don't serve any special purpose.

But please doublecheck that they are really not needed.

> Another one: there are drivers using constructs like:
> 
> #if LINUX_VERSION_CODE > 0x20115
> ...
> #endif
> 
> I understand they can be somehow useful for authors supporting many
> kernel versions with a single set of files, however the gain isn't
> clear to me. Should such conditional code be a) removed, b) left
> in place, c) dealt with each case individually?

c)

Many driver authors share their code this way between different major 
kernel versions, which makes it easier for them to maintain their code.

#ifdef's for kernel 2.4 are often still actively maitained.

#ifdef's for kernel 2.2 are only very rarely actively maitained.

#ifdef's for kernel 2.0 (as in your example) are most likely completely 
obsolete.

> Krzysztof Halasa

cu
Adrian

-- 

       "Is there not promise of rain?" Ling Tan asked suddenly out
        of the darkness. There had been need of rain for many days.
       "Only a promise," Lao Er said.
                                       Pearl S. Buck - Dragon Seed

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