I am learning how to add patches to the source and compile. I put the patch in my rockbox-latest folder and (I am using an example) type "patch < powermgmt.c.patch" this is what I am supposed to do, right? If I enter that and the .patch file empties no new files are made, and the command never finishes (I have to do ctrl-c to type another command). The patch is not applied, what's wrong?