Re: Making ARM multiplatform kernels DT-only?
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On 15:04 Thu 03 May , Russell King - ARM Linux wrote: > On Thu, May 03, 2012 at 01:50:35PM +0000, Arnd Bergmann wrote: > > Hi everyone, > > > > I've been discussing multiplatform kernels with a few people recently, > > and we will have a lot of discussion sessions about this at Linaro > > Connect in Hong Kong. > > > > One question that came up repeatedly is whether we should support all > > possible board files for each platform in a multiplatform kernel, > > or just the ones that are already using DT probing. I would like > > to get a quick poll of opinions on that and I've tried to put those > > people on Cc that would be most impacted by this, i.e. the maintainers > > for platforms that have both DT and non-DT board files at the moment. > > > > My feeling is that we should just mandate DT booting for multiplatform > > kernels, because it significantly reduces the combinatorial space > > at compile time, avoids a lot of legacy board files that we cannot > > test anyway, reduces the total kernel size and gives an incentive > > for people to move forward to DT with their existing boards. > > > > The counterargument is that we won't be able to support all the > > boards we currently do when the user switches on multiplatform, > > but I think that is acceptable. > > Note that I would still want to allow users to build platforms > > separately in order to enable the ATAG style board files, even > > for platforms that are not multiplatform capable. > > I'm basing my comments off mach-zynq. > > How about we take the following steps towards it? > > 1. create arch/arm/include/mach/ which contains standardized headers > for DT based implementations. This must include all headers included > by asm/ or linux/ includes. This will also be the only mach/ header > directory included for code outside of arch/arm/mach-*. This also > acts as the 'default' set of mach/* includes for stuff like timex.h > and the empty hardware.h > > 2. DT based mach-* directories do not have an include directory; their > include files must be located in the main include/ heirarchy if shared > with other parts of the kernel, otherwise they must be in the mach-* > directory. on at91 I'm working to drop it but will have to keep for old non DT board > > 3. Allow build multiple mach-* directories (which we already do... see > the samsung stuff.) > > We still have irqs.h being SoC dependent, and we still haven't taken > debug-macros.S far enough along to get rid of that. Then there's also > the problem of uncompress.h. The last piece of the puzzle is the common > clock stuff. on the decompressor I was thinking to use the DT to select it by using a compatible string if it's ok with you Best Regards, J. -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
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