[yocto] [meta-raspberrypi] How to modify KERNEL_DEVICETREE?

[Drew Moseley]

I'm trying to figure out how to properly modify the KERNEL_DEVICETREE
variable.  It seems that the meta-raspberrypi layer uses that variable
in the sdcard_image-rpi.bbclass and defines it in the machine conf
layer.  In poky, the variable is set and appended to in the various
linux-yocto recipes. If I make a similar change in a linux-raspberrypi
bbappend file, it works fine for the build of the linux-raspberrypi
recipe but when it is trying to package up the rpi-sdimg file, the
changes from the kernel recipe are not available and generally the build
will fail since the files expected during the image creation will not
have been created during the kernel build.

I can envision several different workarounds here but I'm struggling to
come up with a solid fix. Does anyone have any suggestions?

It also looks like the meta-freescale layer will have a similar issue.

Drew