Makefile macro Definition

Cause: When reading the linux0.11 code, it is found that the RAMDisk macro is defined in makefile. Have not been exposed to this usage before, practise it.


Purpose: The macro defined in makefile is used in the C language code.


Content of Makefile:


cc=gcc


RAMDISK =-dramdisk=512


All
$ (CC) $ (RAMDISK) hello.c
Clean
Rm-f a.out
-------------------------------------------------------------------
Hell.c


#include <stdio.h>


int main (void)
{
#ifdef RAMDISK

printf ("RAMDISK =%d\n", RAMDISK);

#else
printf ("NO ramdisk\n");
#endif
return 0;

}

Summing up, it's actually adding parameters to GCC

Makefile macro Definition