Date: Tue, 15 May 2007 18:09:19 +0900
From: Simon Horman <horms@verge.net.au>
To: linux-kernel@vger.kernel.org,
       Fernando Luis Vazquez Cao <fernando@oss.ntt.co.jp>,
       Andrew Morton <akpm@linux-foundation.org>
Subject: Re: [ARM] Fix hard_smp_processor_id compile error
Message-ID: <20070515090917.GA22359@verge.net.au>
References: <20070515022014.CC2A44F910@tabatha.lab.ultramonkey.org> <20070515081907.GA17611@flint.arm.linux.org.uk>
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On Tue, May 15, 2007 at 09:19:07AM +0100, Russell King wrote:
> On Tue, May 15, 2007 at 11:18:50AM +0900, Simon Horman wrote:
> > "Remove hardcoding of hard_smp_processor_id on UP systems",
> > 2f4dfe206a2fc07099dfad77a8ea2f4b4ae2140f in Linus' tree, moved
> > the definition of hard_smp_processor_id linux/smp.h to asm/smp.h
> > for UP systems. This causes a regression on ARM as the definition
> > was not added to asm-arm/smp.h.
> > 
> > Cc: Fernando Luis Vazquez Cao <fernando@oss.ntt.co.jp>
> > Signed-off-by: Simon Horman <horms@verge.net.au>
> 
> I took an alternative approach - since Integrator never had the complete
> SMP support merged, I ripped it out of that platform.  Whether realview
> suffers from the same thing or not I'm not sure - uniprocessor realview
> is not something covered by the ARM default configuration files, and
> therefore kautobuild won't check that configuration.

I can take a look into this. Is there a tree other than Linus'
I should be working with?

> However, the things I find annoying about this is:
> 
> 1. asm/smp.h was _never_ included in ARM UP builds prior to this change.
> 2. we have linux/smp.h and the general rule is that if asm/foo.h and
>    linux/foo.h are present, linux/foo.h is included in preference to
>    asm/foo.h
> 
> Given the amount of janitors we now have looking at the kernel code,
> (2) is a big concern - it could mean a constant stream of patches
> trying to "fix" files including asm/smp.h.
> 
> I would suggest that if there is a desire to include asm/smp.h on UP
> builds, the inclusion of it by linux/smp.h is made unconditional.

I was thinking that myself, though I'm kind of fearful of
what kind of (additional) breakage it might cause.

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