Hi
i have an old petalinux version 0.4 that works with linux kernel version 2.6 .
now i wanna upgrade the kernel version to 3 manually. is it possible?! if yes what i have to do?! can anyone give me a document or article to help me?!

I haven't done any work with embedded but I believe you'd need to set up a kernel build environment for the architecture of your board which is not a trivial thing. You'd probably also have to hack about with the bootloader as well - are you specifically trying to avoid using the SDK from Xilinx ?

This is certainly not trivial - that is a huge undertaking!!! Do you have access to the board support package (BSP)? Patches? Whats the newest kernel version supported for your board?

As kbp stated, you need a buildroot (and cross compiler if your board is not X86), updated patches, boot loader (but not so much, should work if your reading/writing to the same locations), and other things like if you need a watchdog etc... If you have the time and love a serious challenge (this isn't a google it and you will find all answers type problem), this is a do you understand whats going on and knowing your hardware type problem.

Don't want to discourage you, and I'll help you if I can.