Real stupid question. How do I "diff diffs"? That is, if I have patches for, say, v20 and v21, how do I make a patch to update my v20 kernel tree to v21? The diffs are both from clean v2.0b3 installations. Right now what I do is copy in the original files manually to apply the diff, but since I also add in some of my own patches to empeg_input.c and empeg_audio.c, this is a bit of a pain to do each time. Can I do some kind processing with two consecutive patches to make an incremental patch?