I know is old kernel but I am running tests and this message appears in almost every debian system I have tried! make[1]: Entering directory `/usr/src/linux-headers-2.6.26-2-686' CC [M] /home/user/km/km_api.o /home/user/km/km_api.c:22:26: error: linux/config.h: No such file or directory Where is this config.h in linux headers or debian kernel tree i cant find it !