Hi,

With hello kernel module, i use two types of Makefile, one is using kernel build system:

-----------------------------------------------
obj-m += hello.o

all:
make -C /lib/modules/$(shell uname -r)/build M=$(PWD) modules

-----------------------------------------------

module loads successfully;

another is using (CC) and then creating the module by "make -C /lib/modules/$(shell uname -r)/build M=$(PWD) modules", this module gives the error message when it is inserted,

------------------------------------------------
$dmesg:

overflow in relocation type 10 val ffffffff88640070
`mudule_name' likely not compiled with -mcmodel=kernel
-------------------------------------------------

For this Makefile, i need to add
#include <linux/autoconf.h> in hello.c source code for it to build.

Is there anything that needs to be added in Makefile or source code?

One thing that i notice is the second module doesn't have srcversion when using modinfo, the first one has. vermagic is correct on both modules.

The system is 1.6.18-194.el5 x86_64. The second module works fine when it is in i386 machine ( srcversion is not in the module either, but module works).

Thanks!

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#Makefile, mix of (CC) and kernel module build system

CFLAGS+=-D"KBUILD_STR(s)=\#s" -D"KBUILD_BASENAME=KBUILD_STR(hello)"
CFLAGS+=-D__KERNEL__ -DMODULE -I$(KERNEL_BUILD_DIR)/include

KERNEL_BUILD_DIR=/lib/modules/2.6.18-194.el5/build
TARGETNAME=hello
BUILD_ALT_DIR=linux

# The main target (note that both library and driver are .ko files
#
all: $(BUILD_ALT_DIR)/$(TARGETNAME).ko
$(BUILD_ALT_DIR)/_$(TARGETNAME).o: hello.o
@echo Linking objects to loadable module
@mkdir -p $(BUILD_ALT_DIR)
@echo $(CURDIR)/$@
@$(LD) -Map=$@.map -r -o $@ $^
@echo " LD_D [$@]"

$(BUILD_ALT_DIR)/$(TARGETNAME).ko: $(BUILD_ALT_DIR)/_$(TARGETNAME).o
@rm -f $(BUILD_ALT_DIR)/$(TARGETNAME).o
@echo create Makefile
@$(SHELL) -c 'echo "obj-m := $(TARGETNAME).o" > $(BUILD_ALT_DIR)/Makefile'
@$(SHELL) -c 'echo "$(TARGETNAME)-objs := _$(TARGETNAME).o" >> $(BUILD_ALT_DIR)/Makefile'
@$(SHELL) -c 'echo ".PHONY: `pwd`/$(BUILD_ALT_DIR)/_$(TARGETNAME).o" >> $(BUILD_ALT_DIR)/Makefile'
@$(SHELL) -c 'cd $(BUILD_ALT_DIR); $(MAKE) -C $(KERNEL_BUILD_DIR) M=`pwd`'
@echo " KO_D [$@]"


$(BUILD_ALT_DIR)/%.o: %.c
@echo Compiling C source to object file:
@mkdir -p $(BUILD_ALT_DIR)
# @echo $(CURDIR)/$@
@$(CC) -c -Wall $(CFLAGS) $(CFLAGS) $< -o $@
@echo " CC_D [$@]"

clean:
rm -f $(BUILD_ALT_DIR)/*.o $(BUILD_ALT_DIR)/*.d $(BUILD_ALT_DIR)/core $(BUILD_ALT_DIR)/*.map

//hello.c

#include <linux/autoconf.h> // this is needed

#include <linux/init.h>
#include <linux/module.h>

static int hello_init(void)
{
printk(KERN_ALERT "Hello, world\n");

return 0;
}

static void hello_exit(void)
{
printk(KERN_ALERT "Goodbye, cruel world\n");
}

module_init(hello_init);
module_exit(hello_exit);