Hello Jean-Philippe,

>I'm trying to create a simple image that uses the RPI_USE_U_BOOT option but the pi hangs with the rainbow image. I'm able to generate bootable images when not using the RPI_USE_U_BOOT option (but I need to use swupdate).

>I have the same problem with using the Hardknott branch, leading me to think the problem is not the layer but the way I use it.

For me the combination of raspberrypi4-64 machine, U-Boot and RAUC (instead of swupdate) works.

I think the raspberrypi4 should also work (but haven't tested it).

I built and tested my (Poky master branch based) image this morning: https://github.com/matthiasklein/meta-yocto-coffee-rpi

I don't use HDMI output though, but a serial console (ENABLE_UART = "1").

Best regards,

Matthias