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From: Daniel Phillips <phillips@bonn-fries.net>
To: Russell King <rmk@arm.linux.org.uk>
Subject: Re: 2.5.21: kbuild changes broke filenames with commas
Date: Tue, 11 Jun 2002 18:36:44 +0200
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Cc: Keith Owens <kaos@ocs.com.au>, linux-kernel@vger.kernel.org
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On Tuesday 11 June 2002 18:31, Russell King wrote:
> On Tue, Jun 11, 2002 at 06:08:22PM +0200, Daniel Phillips wrote:
> > Are you sure that complexity was added just to handle commas in names?
> > Or is it really an example of how good design never gave this bug a
> > chance to exist in the first palce.
> > 
> > I *really* don't like the idea of papering over such bugs by curing the
> > symptoms, as you seem to be advocating.
> 
> Lets see.
> 
> We have two places in 2.5.21 where commas are unacceptable:
> 
> 1. -DKBUILD_BASENAME=$(subst $(comma),_,$(subst -,_,$(*F)))
> 
>    We need to do this because to do because KBUILD_BASENAME is used in
>    places where commas are not acceptable.
> 
>    We papered over the fact that make can't subst commas by using the
>    $(comma) construct.
> 
> 2. -Wp,-MD,.$(subst /,_,$@).d (currently unfixed)
> 
>    This would need to become something like:
> 
>    -Wp,-MD,.$(subst /,_,$(subst $(comma,_,$@)).d
> 
> So now we have two places where the same yucky substing of commas to
> something more palettable happens.  Now, what if we had:
> 
> 	foo,bar.c
> 
> and
> 
> 	foo_bar.c
> 
> in the same directory?  The kbuild system goes wrong, destroying dependency
> information, using the wrong KBUILD_BASENAME.  Oops.  I guess we papered
> over a bug by allowing commas in filenames.

Yup.

> In addition, I'd like to point out the following paragraph in the make
> info files:
> 
>    The variant variables' names are formed by
>    appending `D' or `F', respectively.  These variants are semi-obsolete
>    in GNU `make' since the functions `dir' and `notdir' can be used to get
>    a similar effect (*note Functions for File Names: File Name
>    Functions.).
> 
> Both kbuild-2.5 and the existing kernel build make heavy use of the
> "$(*F)" notation.  Should we really be putting semi-obsolete features
> into either of the kernel build system?

No, agreed.  Now this is sensible.

-- 
Daniel
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