linux-kernel - Re: [PATCH 1/3] Replace kernel/timeconst.pl with kernel/timeconst.sh

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Date:	Thu, 10 Dec 2009 14:52:44 +0100
From:	Michal Marek <mmarek@...e.cz>
To:	Rob Landley <rob@...dley.net>
Cc:	linux-kernel@...r.kernel.org, "H. Peter Anvin" <hpa@...or.com>,
	linux-kbuild@...r.kernel.org
Subject: Re: [PATCH 1/3] Replace kernel/timeconst.pl with kernel/timeconst.sh

On 10.12.2009 00:40, Rob Landley wrote:
> On Wednesday 09 December 2009 09:45:37 Michal Marek wrote:
>> You're trying to avoid the build dependency on Perl. What about adding a
>> timeconst.h_shipped with the precomputed values from timeconst.pl:
> 
> Been there, done that.  My first patch (way back for 2.6.25) took that 
> approach:
> 
> http://landley.net/hg/hgwebdir.cgi/firmware/file/a791ca629d9c/sources/patches/linux-2.6.25-
> rc1-noperl.patch
> 
> But it turns out various non-x86 targets (such as ARM OMAP) allow HZ to be 
> specified by an entry field in the config file, into which the user can type a 
> range of numbers.  See this post from last year for details:
> 
> http://lists.impactlinux.com/pipermail/firmware-impactlinux.com/2008-
> December/000022.html
> 
> This is why reducing the perl version to just the precomputed constants 
> wouldn't work either.  (They're there so that you only need to install a 
> random cpan library when surprised by a build break on non-x86 machines.)

That's why I wrote

>> plus some makefile automagic to run the script iff the HZ value isn't
>> precomputed. Then you would only need Perl for exotic HZ configurations.

E.g. make it
...
#elif HZ == 1200
...
#else
#include "timeconst_custom.h"
#endif

and the makefile would run timeconst.pl to generate timeconst_custom.h
iff HZ is set to something arbitrary. I don't have a patch for that, but
I don't see a fundamental problem with such approach.

Michal
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