Bug in arch-mmp board selection

On Wed, Jan 5, 2011 at 12:57 PM, Mark F. Brown [off-list ref] wrote:

Hi Eric,

PXA168 and PXA910 are based on PJ1 which is an ARMv5 compatible architecture
MMP2 is a based on PJ4 which configured as ARMv6 currently (there are
ARMv7 versions as well)

Currently all SoCs are selectable under the "PXA168/910/MMP2" menu
option which allows you to then select PXA168, PXA910, and MMP2 boards
for one image. If you build this configuration this error occurs:

?AS ? ? ?arch/arm/kernel/entry-armv.o
arch/arm/kernel/entry-armv.S: Assembler messages:
arch/arm/kernel/entry-armv.S:212: Error: selected processor does not
support `clrex'
arch/arm/kernel/entry-armv.S:244: Error: selected processor does not
support `clrex'
arch/arm/kernel/entry-armv.S:302: Error: selected processor does not
support `clrex'
arch/arm/kernel/entry-armv.S:338: Error: selected processor does not
support `clrex'
make[1]: *** [arch/arm/kernel/entry-armv.o] Error 1
make: *** [arch/arm/kernel] Error 2

I am aware we can resolve this by adding KConfig rules to prevent this
scenario, but it leads to a deeper question. Why does selecting the
board in turn select the CPU type instead of the user enabling the CPU
type and then providing a set of boards for selection?

Because the board knows which SoC it's using, and the logic behind
this is - if you select the board, the board select everything else applicable.

And you are right, it's not able to select all boards in mach-mmp/ to
make them built into a single image at this moment. However, that's
possible theoretically. And that's the reason I'm keeping two separate
_defconfig for pxa168_ and mmp2_.

e.g.
config MACH_ZYLONITE2
? ? ? ?bool "Marvell's PXA168 Zylonite2 Development Board"
? ? ? --> select CPU_PXA168