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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.

Some years ago I would have to patch Torvalds' Kernel to build BBB one, nowadays we have it already patched on github.

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, CONFIG_ARM_APPENDED_DTB, CONFIG_EARLY_PRINTK, CONFIG_DEBUG_AM33XXUART1, CONFIG_DEBUG_OMAP2PLUS_UART, 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.

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Tiago Pimenta
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  • I am passing in my kernel parameters this in my Lamobo R1. "sunxi_fb_mem_reserve=16 hdmi.audio=EDID:0 disp.screen0_output_mode=1920x1080p60" – Rui F Ribeiro Apr 27 '16 at 12:43
  • I have tried video=HDMI-A-1:1024x768@60e and now disp.screen0_output_mode, same result – Tiago Pimenta May 28 '16 at 14:48
  • I tried `video=omapfb:mode:1280x720@60` and there is no `/sys/class/graphics/fb0` directory, only `fbcon`, and I added `fb root:video 0666` to `mdev.conf` with no reaction. – Tiago Pimenta May 28 '16 at 15:38

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