No, I'm not trying to do this in Ubuntu. I used it only for compile the kernel and so. By the way, I used Buildroot to create the images - the system is running in a ARM9 board. I'm trying to use the Digital Persona U.are.U 4000 USB fingerprint reader - that's supported for
libfprint. I've already tested the device in a PC, both in linux and windows. During the compilation of the libraries and dependencies, all went ok. I developed a simple console program to test the functions of the library, and it compiled and run alright, but didn't find the reader - for this reason that I think that is something missing in the kernel config.