2.5.21 drivers/net/hamradio/soundmodem/gentbl needs -lm

drivers/net/hamradio/soundmodem
/tmp/cc6m8eDA.o: In function `gentbl_offscostab':
/tmp/cc6m8eDA.o(.text+0x64): undefined reference to `cos'
...
Makefile uses HOST_LOADLIBES instead of HOST_LOADLIBS. That is what happens when you use magic variables that cannot be syntax checked, errors go undetected until somebody uses the option.

Not a problem for kbuild 2.5 of course, it has a syntax checker.