[Buildroot] Changing the mk file in a package

[Daniel Ng]

Hi,

I'm adding a new package to buildroot. Following the standard docco I add a new 
package directory and the relevant config.in and xxx.mk file.

I've noticed that if I make changes to xxx.mk I have to do a 'make clean' then 
a 'make' ie. a full rebuild. Otherwise if I just try to run 'make' after 
changing xxx.mk, I get the following error from fakeroot-

# Use fakeroot so mkcramfs believes the previous fakery
/home/dng/linuxppc/gcc-4.0.2_uclibc/usr/bin/fakeroot \
        -i /home/dng/linuxppc/gcc-4.0.2_uclibc/fakeroot.env \
        -s /home/dng/linuxppc/gcc-4.0.2_uclibc/fakeroot.env -- \
        /home/ppcroot/swdev/buildroot-dng/build_powerpc/cramfs-1.1/mkcramfs -q -
b \
        /home/ppcroot/swdev/buildroot-
dng/build_powerpc/root /home/ppcroot/swdev/buildroot-dng/rootfs.powerpc.cramfs
Swapping filesystem endian-ness
mkcramfs: mmap failed: /home/ppcroot/swdev/buildroot-
dng/build_powerpc/root/usr/usr/local
make: *** [cramfsroot] Error 8

-but my new package has nothing to do with mmap! 

If I do a full rebuild, I don't get the above problem. But the fully rebuild 
takes about 30 minutes! Is there a way to get a more sensible 'make' behaviour, 
so that I can avoid having to do these full rebuilds?

Cheers,
Daniel