I have successfully followed CLFS book to build RPi and BBB embedded systems. In RPi case the bootloader did not give me problems with device tree.
I can see my kernel working over UART cable, but it does not show on HDMI screen, the original system on eMMC does. I have tried versions 4.4 and 4.1 but the result is the same.
I also built my own U-Boot, I build the kernel with
am335x-boneblack.dtb, and I have tried to build the Bone-Black-HDMI cape and even after successfully installed on
/sys/devices/platform/bone_capemgr/slots, the screen remains empty.
I have also tried to build the kernel with
CONFIG_DEBUG_LL_INCLUDE=debug/omap2plus.S and any combination of them.
How can I enable HDMI on raw BBB kernel? Preferably during the boot, because the way I did it was on
/etc/rc.d/startup, it would take a while till show on screen, although it has not even worked.