Here is a small patch that made my kernel .text segment shrink by 8k IIRC
on my 5272-based board, by removing `-Wa,-S' from CFLAGS.
The `-Wa,-S' option prevents `gas' from using short forms of jsr.
Without it, `gas' replaces `jsr xxx.l' (6 bytes) by `jsr xxx@pc'
(4 bytes) when possible. On 5272, both forms are equally fast.
The `-Wa,-m5307' option is useless, because gcc already gives it
to `gas' from the `-m5307' option.