"The System.map file is still confusing some people judging from
the emails I got, and after reading lengthy discussions about it on
the kernel mailing list."
"Another popular subject for emails I've had have been related
to the article I wrote on kernel patches. In particular, most
people were having problems applying patches written for older
kernels on more recent kernels. In most cases, if you get any
warnings during the patch process, unless you fully understand how
the patch works you should contact the maintainer of the patch and
tell him about the errors. If you notice messages about 'offset 31
lines' or similar, this is not a problem. It just means that the
code above the routine being patched in a file has changed slightly
but the target routine has been found, and patched."