some basic questions about porting uclinux

[zsz]

Hell all,
	For porting ucLinux, I am a beiginer, so I have some basic questions to ask you. My questions are shown as following:
1. What format is the kernel image downloaded into RAM or FLASH by you. Is .hex, .bin or .img? What difference is in them? Whether any one format can run in RAM? 
2. In our system, There are a JTAG port and a parallel port wiggler, but I don't know how to write a GDB stub to support them, and I don't know how does the GDB stub cooperate with the kernel image? Can you tell me some detail or provide me with web pages which describe solutions.
3. I know that ucLinux is without MMU, so can you tell me whether your system is without MMU too? How do you solve the problems about multitasking and dynamic loading applications.
Any Hints is welcome, thank you very much in advance!

Zhao Shengzhe
zsz@chinadigipro.com