Cross compilation doubt

Hello all, just a newbie question!
I’m trying to port an application on a ColibriT30 board and I’m having some linker issues. In the Makefile i have to point to the rootfs location, that is in the LinuxImage package downloaded from Toradex.
When i recompile the Kernel, this rootfs remains the same??
What if I want to add a new library?


Please have a look here.