linux-kernel - Re: [PATCH 1/2] Allow constructor name selection by architecture.

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Message-ID: <20120529092120.GA6433@kyllikki.org>
Date:	Tue, 29 May 2012 10:21:20 +0100
From:	Vincent Sanders <vincent.sanders@...labora.co.uk>
To:	Sam Ravnborg <sam@...nborg.org>
Cc:	Vincent Sanders <vincent.sanders@...labora.co.uk>,
	Russell King <linux@....linux.org.uk>,
	Arnd Bergmann <arnd@...db.de>, linux-kernel@...r.kernel.org,
	Andrew Morton <akpm@...ux-foundation.org>,
	linux-arm-kernel@...ts.infradead.org
Subject: Re: [PATCH 1/2] Allow constructor name selection by architecture.

On Mon, May 28, 2012 at 10:30:05PM +0200, Sam Ravnborg wrote:
> On Mon, May 28, 2012 at 07:33:37PM +0100, Vincent Sanders wrote:
> > From: Vincent Sanders <vince@...labora.co.uk>
> > 
> > The constructor symbol name is different between platforms. Allow this
> > to be selected by configuration and set suitable default values.
> > 
> > Signed-off-by: Vincent Sanders <vincent.sanders@...labora.co.uk>
> > ---
> >  include/asm-generic/vmlinux.lds.h |    6 +++---
> >  init/Kconfig                      |    6 ++++++
> >  kernel/module.c                   |    2 +-
> >  3 files changed, 10 insertions(+), 4 deletions(-)
> > 
> > diff --git a/include/asm-generic/vmlinux.lds.h b/include/asm-generic/vmlinux.lds.h
> > index 8aeadf6..fd34808 100644
> > --- a/include/asm-generic/vmlinux.lds.h
> > +++ b/include/asm-generic/vmlinux.lds.h
> > @@ -471,9 +471,9 @@
> >  	}
> >  
> >  #ifdef CONFIG_CONSTRUCTORS
> > -#define KERNEL_CTORS()	. = ALIGN(8);			   \
> > -			VMLINUX_SYMBOL(__ctors_start) = .; \
> > -			*(.ctors)			   \
> > +#define KERNEL_CTORS()	. = ALIGN(8);					\
> > +			VMLINUX_SYMBOL(__ctors_start) = .;		\
> > +			*(CONFIG_CONSTRUCTORS_NAME)			\
> >  			VMLINUX_SYMBOL(__ctors_end) = .;
> 
> What is wrong with adding both "standard" names for ctors uncnditionally?
> Like this:
> > 			*(.ctors)			   \
> > +			*(.init_array)			   \
> 

Persoinally I have no strong opinion and would alter approach.

As I understand it the previous objections to the "put them all in"
approach (this change has been round the loop before) were:

 - It contaminates the x86 symbol namespace and if init_array was used on
   not ARM it might lead to surprises

 - If another architecture needs something different again then we are
   going to end up with another symbol.

 - The module loading code has to be changed to allow either symbol.

The only technical issue really is the module symbol handling and I am
unsure how to robustly handle that.

-- 
Regards Vincent
http://www.kyllikki.org/
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