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66AK2G12: What is the difference between MLO and u-boot.img?

Part Number: 66AK2G12

Hello, 

I am confused about the secondary boot loader and u-boot loader files. My understanding is that MLO is the secondary boot loader and is loaded into memory by the boot ROM. It's purpose is to configure essential hardware in preperation for the user application or u-boot. On the other hand I understand that u-boot.img is the binary for u-boot loader. 

After building u-boot I accidently only placed MLO only on the sd-card and to my surprise the system booted. I then earased the sd card, re created the partion and tried agin. The system booted again, therefor since I could repeat this result many times, I came to the conclusion that only MLO is required to boot the device. Is this a good conclusion? 

What is the difference between these two files ? Do I need to include them both and if not which one should I use ?

Luke

  • Hi Luke,
    You're right that there are generally two files - MLO and u-boot.img for booting from SD card on most of TI Sitara devices.
    But on building u-boot using "k2g_evm_defconfig" for K2G EVM, there's a generated file ".MLO.cmd" as listed below
    "cmd_MLO := ./tools/mkimage -A arm -T gpimage -C none -a 0xC000000 -e 0xC000000 -n U-Boot -d u-boot.bin MLO >/dev/null"
    So MLO is essentially u-boot.bin for SD booting on K2G EVM.
    This is also noted in the section "Load and Run U-Boot on K2G EVMs using MMC" in "u-boot/board/ti/ks2_evm/README".
    Best,
    -Hong

  • Thank you for the clarification Hong, it's now clear.