Hi, I tried the solution of extracting the idbloader.img from the official OrangePi image and flashing it at the appropriate address, as suggested in one of the previous posts. I tried this with the latest official Armbian Gnome image for OPi 5b. While it did boot, dmesg returned some errors and bluetooth did not work. I didn't inspect if there were more devices affected. The thing is that the boot process consist of several stages as described in the official Rockchip wiki: https://opensource.rock-chips.com/wiki_Boot_option
Take a look at the "Boot Flow 2" in the boot flow chart. It involves idbloader.img and u-boot.itb binaries. Both are present in u-boot package inside the official OPi image. When I flashed both, each to the address specified in the wiki linked above, I got everything working.
There is, however, an easier way to patch the bootloader. Go to Joshua Riek's Ubuntu Rockchip download page: https://joshua-riek.github.io/ubuntu-rockchip-download/ Download the image for your board and flash it to SD card. After flashing, copy the Armbian image to the same SD card. Don't forget to change the overlay (in the Armbian image) in the /boot/armbianEnv.txt as instructed in the official Armbian OPi5/5B page: https://www.armbian.com/orangepi-5/ Insert the SD card in your OPi5B and boot Ubuntu Rockchip from it. Open the terminal and use the dd command to flash the Armbian image to the emmc as described in the official OPi5B board user manual available at the board manufacturer's website. After that, just run sudo u-boot-install /dev/mmcblkX where you need to replace X with the appropriate number for your emmc (usually mmcblk0). This will install u-boot supplied with the Ubuntu Rockchip to emmc. Notice from the output that the command basically flashes the two binaries mentioned earlier, probably using the dd command. Power off, eject the SD card and try powering on. The board shoud boot Armbian from emmc.
