There are several questions on the topic: Between the moment of transfer of control to the kernel from the u-boot and the moment of start of the kernel operation it takes 1.5 -2 minutes. I assume that during this period of time there is decompression of the code and placement in memory. But why so long? The 4.4.x kernel starts instantly. When I first turned on a nanopc-t4 with a 5.x.x (4.20) kernel, I already thought the kernel was corrupted. And quite accidentally waited for the green LED