I've successfully used buildroot (Buildroot 2016.05-git-01014-g4896b7c) with the raspberypi_defconfig to build a Raspberry Pi bootable image. This default configuration is set to use kernel header version 4.1.5 and it boots the Pi successfully.
My goal is to build a Blue Tooth driver for the Raspberry Pi but the code available requires a version of the kernel headers greater than 4.2.x. So I've modified buildroot's .config file to use a custom version of the kernel header 4.4.x series with the following (https://github.com/raspberrypi/linux.git) URL of custom repository (36bb5f17fc320d38d4e887aae8ff13806bb0f672) Custom repository version. This version was recently merged from the remote tracking branch 'stable/linux-4.4.y' into rpi-4.4.y. I've made no other changes to the .config file.
The Buildroot 'make' completes without error but the resultant image won't boot the Raspberry Pi.
Build using : Linux version 4.4.8 (ed@linux-dev) (gcc version 4.9.3 (Buildroot 2016.05-git-01014-g4896b7c)
During boot it only gets as far as the splash screen.
My question are:
1) Am I being too naive to expect the image based on the 4.4.8 kernel headers to boot at all?
2) What strategy can I use to try and diagnose why it won't boot?
3) What do others developers do in these circumstances?
I will appreciate your help with this problem.