What are all the mandatory content of the boot partition?

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http://unix.stackexchange.com – While studying about booting an android on any board, I have learnt that MLO(X-loader), U-boot and uImage are necessary to boot the android on board. But I wondered that when I have come to know about that, the IMX53quickstart Board does not need MLO to boot an android on it. 1.How can it possible? How can the board boot without MLO? 2.Is this board have any special feature? What is that? If so, 3.`Why another board couldn't have this feature?` 4. can we implement this feature on all board? Please consider my question and clear my confusion. Thank u in advance. (HowTos)