1) create a root file system. To create a root file system, copy the required root file to a directory and compress it with the compression command in the specified format. 2) Compile the file system into the kernel. The specific method is to specify the root file path generated in the first step when compiling the kernel, and then compile it. Kernel options: # General setup #... CONFIG_BLK_DEV_INITRD = yCONFIG_INITRAMFS_SOURCE = "<path_to>/target_fs> "... # UBI-Unsorted block images #... CONFIG_BLK_DEV_RAM = yCONFIG_BLK_DEV_RAM_COUNT = 1CONFIG_BLK_DEV_RAM_SIZE = memory = 10243) Put the kernel directly into sd or nand. The system encountered this problem during system startup: 1. WARNING: Unable to open an initial console solution: Add: cd/devmknod-m 660 console c 5 1 mknod-m 660 null c to the root file 1 32. The init program cannot be found when the system starts. Solution: create a link to point it to the init program. 3. The library file may not be found when the system starts to level 5. Solution: directly copy the missing library file to the root file system