Single zImage and A15/LPAE

[Olof Johansson]

On Tue, May 28, 2013 at 7:02 PM, Olof Johansson <olof at lixom.net> wrote:
> On Tue, May 28, 2013 at 6:54 PM, Nicolas Pitre <nicolas.pitre at linaro.org> wrote:
>> On Wed, 29 May 2013, Kukjin Kim wrote:
>>> (+ Olof, Russell)
>>>
>>> Just note, I found this in my old mail-box...
>>>
>>> So I think, as a result, we need to support separate kernel binary for LPAE
>>> and non-LPAE and you guys don't hold a different view about it.
>>
>> LPAE and non-LPAE configurations will most likely never be supported
>> together in the same kernel binary.  The runtime cost would simply be
>> too high to be worth it.
>>
>>> Current SSDK5440 and SD5v1 boards which are reference boards for EXYNOS5440
>>> has over 4GB memory as a default and that's why I'm writing this e-mail. It
>>> means I should keep separated kernel to support exynos5440 and other exynos
>>> SoCs.
>>
>> They could all be supported together but with less than 4GB of memory.
>
> Or the other way around, the other EXYNOS5 CPUs could all enable LPAE
> even if they have less than 4GB of memory -- but not EXYNOS4, of
> course.
>
> However, instead of forking off and duplicating otherwise
> near-identical defconfigs, I suggest just getting your developers used
> to passing in CONFIG_LPAE=y on the build command line instead (or in
> their local configs for their products, of course). That way there's
> less duplication and no need to enable drivers in two places, etc.

Nevermind, I'm smoking crack, that doesn't seem to actually work.
(Besides, it's CONFIG_ARM_LPAE).


-Olof