I found in minix F4 it not used i entered to /usr/src/kernel
and keyboard.c
and add a simple code at F4
the Code :
case F4 : printf("%s\n","Hello"); break;

and i try to compile this file by this command

#cd /usr/src/kernel
#make install
#cd /usr/src/tools
#make hdboot

it not give me any error

and after reboot there has no action
Please ------> What's the Problem !