[yocto] One kernel tree, two BSP layers, two defconfigs. How to pickup the right one based on MACHINE value?

[Daniel.]

Hi,

I have one kernel tree where I keep all my modules in-tree. Inside
kernel I have two FOO_defconfig and BAR_defconfig which are
configurations for FOO-board and BAR-board. On Yocto I have
core-layer, FOO-bsp layer and BAR-bsp layer. At core-layer I have
linux-custom.bb file which has the URI for kernel tree with a dummy
defconfig. At FOO-bsp and BAR-bsp a have a .bbappend that adds a
folder with the right defconfig for each board.

My doubt is: I have two .bbappends, on two distinct layers being
applied at same time? Both layers are pointed at
build/conf/bblayers.conf.

How can I have sure to pick up the right defconfig at build time?

I've tried to delete core-layer and have two kernel recipes with
distinct names, but Yocto complains about two recipes being selected
at same time for build (because of virtual/kernel feature or something
alike). So I want to keep one kernel recipe and select the right
defconfig based on MACHINE value.

Both defconfig are present on arch/arm/configs. Can I overwrite
do_config()? Is that safe? About the .bbappends: Should be two
.bbappends on same .bb file be avoided?


Regards,
- dhs
-- 
"Do or do not. There is no try"
  Yoda Master