Re: [PATCH 09/32] bcm2837-rpi-3-b.dts for 32bit arm

On Thursday, June 2, 2016 11:14:30 AM CEST Gerd Hoffmann wrote:

  Hi,

quoted

quoted

Well, it just includes the arm64 version as-is, so we don't have
duplication.  I'm open to suggestions to how handle this better.  

Symbolic link?

Reference to ../../../arm64/boot/dts/broadcom/bcm2837-rpi-3-b.dts
directly in the Makefile?

I've seen arch/arm/boot/dts/Makefile uses globs on *.dts, so I suspect
the later wouldn't be that straight forward.

It's just weird that the arm64 file includes the .dtsi files from arch/arm/
and is then again included back from another file there.

I can see two possible ways to handle this better:

- leave the complete set of bcm2837 files in arch/arm and then have one
  reference from arch/arm64 per .dts that refers to just that file.

So basically do it the other way around.  Would be a bit less messy
indeed.

quoted

- come up with a rule to also build the .dtb files in arch/arm64 when
  we run 'make dtbs' for arch/arm and leave this file there. The argument
  that one could use the same dtb with a 32-bit kernel should basically
  hold true for any arm64 system, it's not specific to rpi-3 really.

Yes, in theory.  No, in practice.  As far I know the rpi3 is the only
64bit soc where a almost identical 32bit version exists, so running
32bit kernels on a 64bit processor actually happens in practice and I
expect this to continue.  If you want create sdcard images which run on
any rpi variant this is pretty much the only reasonable way to do it.

I think the Allwinner A64 and the Samsung s5p6818 are other examples
for this, where the initial run of boards all run 32-bit kernels
for much of the same reasons. If users want to run a 32-bit distro
on rpi-3 and on e.g. orange-pi, I don't see why they wouldn't also run
the same binary on A64.

	Arnd
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