[PATCH 10/62] ARM: efm32: select AUTO_ZRELADDR

On Friday 21 March 2014, Rob Herring wrote:

On Fri, Mar 21, 2014 at 1:54 PM, Uwe Kleine-K?nig [off-list ref] wrote:

quoted

On Fri, Mar 21, 2014 at 04:10:37PM +0100, Arnd Bergmann wrote:

quoted

I don't see a reason to change the existing logic, it works for
both MMU and NOMMU kernels, and you are talking about three instructions
here.

it doesn't matter how many instructions are involved. The relevant
difference is that with my approach you fix the problem for all no-MMU
platforms, with yours you only fix efm32. (OK, I think there are not too
many no-MMU platforms, but still.) An even easier implementation would
be to add something like:

        ifeq($(zreladdr-y)$(CONFIG_MMU),)
        zreladdr-y := CONFIG_PAGE_OFFSET + CONFIG_TEXT_OFFSET
        endif

to arch/arm/boot/Makefile.

This makes sense, we can add it as soon as we have a use for it. At the
moment, the only problem we have is a randconfig build error, and the
obvious change I proposed should work just fine.

quoted

But I don't care much, if you still want to make EFM32 select
AUTO_ZRELADDR go ahead.

How about a kconfig fix:

bool "Auto calculation of the decompressed kernel image address" if MMU
default y if !MMU

This however would break builds that today for some reason cannot use
AUTO_ZRELADDR on !MMU kernels, i.e. has a funny bootloader that
uses ZBOOT_ROM or other tricks. In principle any platform should
work with MMU disabled (although I'm sure there are tons of bugs),
and not every one uses AUTO_ZRELADDR today. Uwe's suggestion above
takes advantage of the fact that !MMU-kernels know what physical
address they run on.

	Arnd