Difference between zImage.treeboot zImage

Hi,

I'm using opebios on IBM redwood6 ppc405 platform. Currently when I compile my kernel by doing "make zImage" I get one file zImage.treeboot. I just want to know what is the difference between normal zImage and zImage.treeboot.

One more thing I've noticed that there is also a small boot program inside the kernel also (arch/ppc/boot/simple) which decompresses the kernel and jumps to start of zImage. Why this is required ? In normal U-boot which I've worked earlier directly decompresses the zImage by bootm command and starts its execution. Please help me in understanding this mechanism.

Also If I want to build linux kernel 2.6 then will my opebios will work with it or I'll have to change to uboot for for 2.6 kernel.


regards,
Akhilesh