To compile a LKM with an implicit function with kernel >= 2.6.23, please
change the CFLAGS in /usr/src/linux/Makefile :

	CFLAGS          := -Wall -Wundef -Wstrict-prototypes -Wno-trigraphs \
	                   -fno-strict-aliasing -fno-common \
			   -Werror-implicit-function-declaration

=============>

	CFLAGS          := -Wall -Wundef -Wstrict-prototypes -Wno-trigraphs \
	                   -fno-strict-aliasing -fno-common