place a simple /proc, support debug build with Makefile

1 files changed, 18 insertions, 6 deletions

diff --git a/Makefile b/Makefile
index a4b3494..aced26e 100644
--- a/Makefile
+++ b/Makefile
@@ -1,14 +1,20 @@
-# causes weird file size, smaller than stripped?
-ifeq ($(DEBUG),)
-  ccflags-y += -g
-endif
-
 # Makfile assignments:
 #  := value at right is expanded and assigned at declaration time
 #   = value at right is expanded only when it is used, hence it is a reference
 #  ?= value at right is assigned only if the variable doesn't have a value
 #
-#
+
+# run following to compile with debug options
+# $ DEBUG=1 make
+ifneq ($(DEBUG),)
+  DEBUG_FLAGS = -O0 -g -DHELLO_DEBUG
+endif
+
+# see Documentation/kbuild/makefiles.txt
+EXTRA_CFLAGS += $(DEBUG_FLAGS)
+
+ifneq ($(KERNELRELEASE),)
+# call from kernel build system
 
 # objects that are part of hello module (hello.o)
 #hello-objs += main.o debug.o
@@ -17,14 +23,20 @@ hello-y += main.o debug.o
 # .ko module to be created
 obj-m := hello.o
 
+# normal makefile, not kbuild
+else
+
 KERNELDIR ?= /lib/modules/$(shell uname -r)/build
 
 # '-C' changes the dir
 # '-M' causes the the kernel's toplevel Makefile to move back into this dir
 #      before trying to build 'modules' target
+#      and it informs kbuild that an external module is being built
 all:
 	make -C $(KERNELDIR) KCPPFLAGS="-I$(CURDIR)" M=$(PWD) modules
 
+endif
+
 kclean:
 	make -C $(KERNELDIR) M=$(PWD) clean