On Mon, Oct 22, 2012 at 09:33:51AM +0900, Simon Horman wrote:

On Fri, Oct 19, 2012 at 08:18:50AM +0000, Arnd Bergmann wrote:

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On Friday 19 October 2012, Simon Horman wrote:

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On Thu, Oct 18, 2012 at 05:13:10PM +0900, Simon Horman wrote:
I have made a limited amount of progress on this trying to create a
defconfig that will work on both the Marzen and Armadillo 800 EVA boards.

* Serial console appears to work, although for the Marzen at
  least enabling earlyprintk seems to require the bootloader to specify
  e.g.  console=ttySC2,115200 earlyprintk

  This is done by fully specifying bootargs in U-Boot.
  The boodloaders on the Marzen board has an ampty bootargs by default.

  I guess I can live without earlyprink by default,
  though it does seem to be a regression in the user experience.

Right. So who is using the defconfig for these boards? Usually most
people using it actually have their own configuration files that are
tuned for their needs, and you often also need to change the command
line in order to configure the root partition etc.

I imagine they are primarily used by developers, like myself, but
to be honest I am unsure. Ideally I would like the defconfig to be as
useful as possible out of the box. But I agree that most users probably
end up making some customisations, e.g. to the location of the rootfs.

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* A more significant problem seems to be the use of CONFIG_MEMORY_START
  to define PLAT_PHYS_OFFSET in arch/arm/mach-shmobile/include/mach/memory.h

  I'm not sure that I see an easy way to get around this one.

ARM_PATCH_PHYS_VIRT should take care of this, have you tried it?

I believe that this leaves mach-shmobile with three areas
where CONFIG_MEMORY_START/PLAT_PHYS_OFFSET is used.

* arch/arm/mach-shmobile/headsmp.S

  This uses PLAT_PHYS_OFFSET.

  I believe this can be replaced with a run-time calculation. Though I
  haven't thought about the details yet.

* arch/arm/boot/compressed/head-shmobile.S

  This makes use of CONFIG_MEMORY_START.

  This is only used if CONFIG_ZBOOT_ROM is set.

  I'm unsure if this can be replaced with a run-time calculation or not.
  But regardless it is only used if CONFIG_ZBOOT_ROM is set, which is not
  the default at this time.


* arch/arm/mach-shmobile/Makefile.boot

 This makes use of CONFIG_MEMORY_START to set zreladdr.

 I believe that the solution to this is to make use of CONFIG_AUTO_ZRELADDR.
 However, it is not yet clear to me how that can be used in conjunction
 with a uImage.  As I understand it the boot loader on many of our boards,
 including the Marzen board which is my first target for this work, boot
 uImage imagess.