Re: [PATCH 0/4] [RFC] ARM: multiplatform: rename all mach headers

From: Arnd Bergmann <arnd@arndb.de>
To: Nicolas Pitre <nicolas.pitre@linaro.org>
Cc: linux-arm-kernel@lists.infradead.org,
	linaro-kernel@lists.linaro.org, linux-kernel@vger.kernel.org
Subject: Re: [PATCH 0/4] [RFC] ARM: multiplatform: rename all mach headers
Date: Wed, 22 Aug 2012 15:31:42 +0000	[thread overview]
Message-ID: <201208221531.42845.arnd@arndb.de> (raw)
In-Reply-To: <alpine.LFD.2.02.1208221106010.1754@xanadu.home>

On Wednesday 22 August 2012, Nicolas Pitre wrote:
> On Wed, 22 Aug 2012, Arnd Bergmann wrote:
> > There are two branches available in the arm-soc tree:
> > 
> > 1. This series,
> >    http://git.kernel.org/?p=linux/kernel/git/arm/arm-soc.git;a=shortlog;h=refs/heads/testing/mach-headers
> >    This just moves header files around and changes most of the
> >    files including them. There are a few remaining drivers
> >    and platform files that keep including a generic file name
> >    like <mach/uncompress.h>. It remains possible to do that,
> >    and I've run extensive tests to ensure I did not break
> >    anything with this. However, each of these instances means
> >    that there is something that stops working when you get to
> >    the real multiplatform kernel and we still need to deal
> >    with them one by one.
> 
> The content of <mach/uncompress.h> is fundamentally machine or SOC 
> specific.  We already know it is generally incompatible with a multi 
> platform kernel.  So the best way to deal with this at the moment is 
> probably to just provide a dummy uncompress.h with empty stubs whenever 
> CONFIG_ARCH_MULTIPLATFORM is selected.  The effect from this is that 
> there wouldn't be any "Uncompressing the kernel... Done" output anymore, 
> which should be an acceptable compromise until a better solution is 
> found.

Yes, that is what I do in the second series.

> One problem is that some (very few) machines define a method in that 
> file to keep a hardware watchdog alive.  This might not be the case for 
> all the intended targets to gather in a single kernel binary image 
> though.

Ok. I think we have a list of known issues somewhere, we should add this
one. I just can't remember where that list is located.

> Another issue is the fact that some platforms do very ugly 
> layer-violating hacks where the decompressor selects a serial port for 
> early output and then store that selection in some arbitrary memory 
> location for the main kernel to blindly use, making the decompressor 
> mandatory.  OMAP and Davinci are prime example of such "abuse" which 
> would need to be fixed.

Same thing here I guess.

Thanks for the input!

	Arnd