About how to start from NAND Flash

After the NAND is all formatted today, re-use the uboot in nor to burn the uboot into the NAND. It should be the same as the uboot interface in nor. The following message is prompted: #### embedsky BIOS for sky2440/tq2440 #####
Press space key to download mode!
Booting LINUX...
Copy Linux kernel from 0x00200000 to 0x30008000, size = 0x00200000... Copy Kern
El to SDRAM done, warning: This binary is not compressed Linux kernel Image
Zimage magic = 0 xffffffff
Now, booting LINUX ......
Undefined instruction
PC: [<30f0c550>] LR: [<33d81760>]
SP: 33d3ded4 IP: c0000000e FP: bfefdfdd
R10: ffffffff R9: fbfcb3dc R8: 33d3ffdc
R7: fbfbf725 R6: 00000000 R5: 000000a8 R4: 30008000
R3: c0001_c R2: 30008000 r1: 000000a8 R0: 00000000
Flags: nzcv irqs off fiqs off mode svc_32
Resetting CPU... *** warning-bad CRC or nand, using default environment ##### embedsky BIOS for sky2440/tq2440 #####
Press space key to download mode!
Booting LINUX...
Copy Linux kernel from 0x00200000 to 0x30008000, size = 0x00200000... Copy Kern
El to SDRAM done, warning: This binary is not compressed Linux kernel Image
Zimage magic = 0 xffffffff
Now, booting LINUX ......
Undefined instruction
PC: [<30f0c550>] LR: [<33d81760>]
SP: 33d3ded4 IP: c0000000e FP: bfefdfdd
R10: ffffffff R9: fbfcb3dc R8: 33d3ffdc
R7: fbfbf725 R6: 00000000 R5: 000000a8 R4: 30008000
R3: c0001_c R2: 30008000 r1: 000000a8 R0: 00000000
Flags: nzcv irqs off fiqs off mode svc_32
Resetting CPU... * ** how does warning-bad CRC or NAND and using default environment do this? uboot is also written. Why is it different? Later I asked the group owner why, he said it was because the kernel was not burned. I said I didn't burn the kernel. I just ran the NAND full grid and then burned the uboot. Why is it different. The landlord said that press the Space key to start the system, and that is the same, because the default nand flash Boot system is 8: boot system, and the prompt message says the kernel cannot be found. Now I understand. I did another experiment, started from nor, and then selected 8: Boots system. The result is the same as the previous phenomenon. Check the prompt message at startup: enter your selection: 8
Start Linux...
Copy Linux kernel from 0x00200000 to 0x30008000, size = 0x00200000... Copy Kern
El to SDRAM done, now, booting LINUX ......
Uncompressing Linux ...................................... .......................
........................................ ..................... Done, booting
Kernel. No matter which method the kernel is started, the kernel is copied from ox00200000 to 0x30008000 of the sdram, (the actual address of the SDRAM is 0x30000000) and then started to start the kernel.