[U-Boot] [PATCH v4 26/26] sunxi: A64: add 32-bit SPL support

[André Przywara]

On 16/01/17 08:55, Maxime Ripard wrote:
> On Fri, Jan 13, 2017 at 09:42:28AM +0000, Andre Przywara wrote:
>>> Re wanting to build SPL either as 32-bit or 64-bit, could this be a
>>> Kconfig option perhaps?
>>
>> Sounds like a direction worth to investigate.
>> In the moment we have two separate defconfig files, because CPU_V7 and
>> ARM64 are actually mutually exclusive, which is really a pain and the
>> main reason that part wasn't merged.
> 
> I really like that option.

So I gave this a try this weekend, I have something like:

+choice
+	prompt "32/64 bit build selection"
+	depends on MACH_SUN50I
+
+config SUNXI_64BIT_BUILD
+	bool "64-bit Aarch64 build"
+	select ARM64
+
+config SUNXI_32BIT_BUILD
+	bool "32-bit ARM build"
+	select CPU_V7
+	select PHYS_64BIT
+
+endchoice

I then set CONFIG_SUNXI_64BIT_BUILD=y in the defconfig.
That seems to work, however switching to a 32-bit build requires either
a) a separate defconfig - which is what we didn't want
b) manually toggling this via menuconfig
c) sed-ing these two lines in .config

I was hoping that there was some simple command line way of toggling a
Kconfig option, à la:
$ make pine64_plus_defconfig CONFIG_SUNXI_32BIT_BUILD=y

But that didn't work.
mergeconfig.sh wasn't helpful as well.

Any ideas on how we could easily switch between the two options?

Cheers,
Andre.