@werner, thanks for the information and the clarification on my concern in the documentation. This sounds like an interesting project, I do believe I'll give it a try. Again, thank you for the encouragement and the pointers.

Admittedly, I had not tested the DTBO at runtime so far, but only applied it statically to the base DTB and checked whether all desired changes were made as intended. Now I am running my device with the applied overlay and I get the following: [ 0.940862] mmc0: new HS200 MMC card at address 0001 [ 0.941665] mmcblk0: mmc0:0001 A3A561 57.6 GiB [ 0.943039] mmcblk0: p1 p2 [ 0.943767] mmcblk0boot0: mmc0:0001 A3A561 4.00 MiB [ 0.945199] mmcblk0boot1: mmc0:0001 A3A561 4.00 MiB [ 0.946661] mmcblk0rpmb: mmc0:0001 A3A561 16.0 MiB, chardev (506:0) So everything is as expected, and yes, I have ensured that my system is running with the applied overlay. In the past, I have at least once noticed far too late that my system was running in a fallback, and a feature to be tested was not applied at all. That's just the disadvantage of a fail-safe system that only leaves a non-functional system in an extreme exceptional situation. Since you haven't provided meaningful logs, I can't say what is going wrong on your end. To rule out an error when applying the overlay, you could start your system with this DTB (rk3588-nanopc-t6.dtb) , which already contains the overlay applied statically.

Thank you. What do you suggest I do? I'm not sure that the "update bootloader" choices are showing the correct devices either.

What exactly have you installed on the SD card (version, image name), and what steps have you used to install?

same problem， and 25.11.0-trunk.129 img dont work