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cbuildlinux-kernelkernel-modulekbuild
Иво Стратев
Иво Стратев

Reputation: 415

Main file not compiling when compiling kernel module from multiple files

First I want to say that I have been searching for similar problems and what is the solution. And I found that it is:

obj-m := module.o
module-objs := extra.o

But it dosen't work for me ...

Here is the whole project source:

axis_controller.h:

#ifndef _AXIS_CONTROLLER_H
#define _AXIS_CONTROLLER_H

#include <linux/kernel.h>
#include <linux/module.h>
#include <linux/hrtimer.h>
#include <linux/ktime.h>

struct axis_controller {
    struct hrtimer timer;
    int state;
};

static inline struct hrtimer* axis_controller_get_timer(struct axis_controller* axis_controller);

static inline void axis_controller_reset_state(struct axis_controller* axis_controller);

inline void axis_controller_init(struct axis_controller* axis_controller, enum hrtimer_restart (*function)(struct hrtimer *));

inline int axis_controller_clean(struct axis_controller* axis_controller);

inline void axis_controller_change_state(struct axis_controller* axis_controller, unsigned long sec, unsigned long nano_sec);

inline void axis_controller_controll(struct axis_controller* axis_controller);

#endif

axis_controller.c:

#include "axis_controller.h"

MODULE_LICENSE("GPL v2");

struct hrtimer* axis_controller_get_timer(struct axis_controller* axis_controller) {
    return &(axis_controller->timer);
}

void axis_controller_reset_state(struct axis_controller* axis_controller) {
    axis_controller->state = 0;
}

void axis_controller_init(struct axis_controller* axis_controller, enum hrtimer_restart (*function)(struct hrtimer *)) {
    hrtimer_init(axis_controller_get_timer(axis_controller), CLOCK_MONOTONIC, HRTIMER_MODE_REL);
    axis_controller->timer.function = function;
    axis_controller_reset_state(axis_controller);
}

int axis_controller_clean(struct axis_controller* axis_controller) {
    return hrtimer_try_to_cancel(axis_controller_get_timer(axis_controller));
}
void axis_controller_change_state(struct axis_controller* axis_controller, unsigned long sec, unsigned long nano_sec) {
    axis_controller->state = !axis_controller->state;
    hrtimer_start(axis_controller_get_timer(axis_controller), ktime_set(sec, nano_sec), HRTIMER_MODE_REL);
}
void axis_controller_controll(struct axis_controller* axis_controller) {
    axis_controller_reset_state(axis_controller);
    axis_controller->timer.function(axis_controller_get_timer(axis_controller));
}

//printk(KERN_INFO "axis_controller.c\n");

CNC_controller.c:

#include <linux/kernel.h>
#include <linux/module.h>
#include "axis_controller/axis_controller.h"

MODULE_LICENSE("GPL v2");
MODULE_AUTHOR("Ivo Stratev (NoHomey)");
MODULE_DESCRIPTION("CNC Controller");

printk(KERN_INFO "CNC_controller.c\n");

static int return_value;
static struct axis_controller test;

static enum hrtimer_restart my_callback(struct hrtimer *timer) {
  printk(KERN_INFO "my_hrtimer_callback called\n");
  return HRTIMER_NORESTART;
}

static int __init on_load(void) {
  printk("on_load\n");
  axis_controller_init(&test, my_callback);

  axis_controller_controll(&test);

  return 0;
}

static void on_unload(void) {
  printk("on_unload\n");
  axis_controller_clean(&test);
  return;
}

module_init(on_load);
module_exit(on_unload);

Makefile:

__name__ = CNC_controller
__major__ = 243
__ioctl_header__ = /usr/include/$(__name__)_ioctl.h
make_module_action = make -C /lib/modules/$(shell uname -r)/build M=$(PWD)
obj-m := $(__name__).o
CNC_controller-objs := axis_controller/axis_controller.o

all: clean
    $(make_module_action) modules

clean:
    $(make_module_action) clean

load:
    insmod $(__name__).ko

unload:
    rmmod -f $(__name__)

device:
    mknod /dev/$(__name__) c $(__major__) 0
    chmod 777 /dev/$(__name__)

remove:
    rm -f /dev/$(__name__)

header:
    rm -f $(__ioctl_header__)
    cp $(__name__).h $(__ioctl_header__)
    chmod 555 $(__ioctl_header__)

This is the build process:

ivo@ivo-Inspiron-5558:~/CNC-Controller$ make
make -C /lib/modules/4.4.0-28-generic/build M=/home/ivo/CNC-Controller clean
make[1]: Entering directory '/usr/src/linux-headers-4.4.0-28-generic'
CLEAN   /home/ivo/CNC-Controller/.tmp_versions
CLEAN   /home/ivo/CNC-Controller/Module.symvers
make[1]: Leaving directory '/usr/src/linux-headers-4.4.0-28-generic'
make -C /lib/modules/4.4.0-28-generic/build M=/home/ivo/CNC-Controller modules
make[1]: Entering directory '/usr/src/linux-headers-4.4.0-28-generic'
CC [M]  /home/ivo/CNC-Controller/axis_controller/axis_controller.o
LD [M]  /home/ivo/CNC-Controller/CNC_controller.o
Building modules, stage 2.
MODPOST 1 modules
CC      /home/ivo/CNC-Controller/CNC_controller.mod.o
LD [M]  /home/ivo/CNC-Controller/CNC_controller.ko
make[1]: Leaving directory '/usr/src/linux-headers-4.4.0-28-generic'
ivo@ivo-Inspiron-5558:~/CNC-Controller$

When I remove the line

CNC_controller-objs := axis_controller/axis_controller.o

The building process is:

ivo@ivo-Inspiron-5558:~/CNC-Controller$ make
make -C /lib/modules/4.4.0-28-generic/build M=/home/ivo/CNC-Controller clean
make[1]: Entering directory '/usr/src/linux-headers-4.4.0-28-generic'
CLEAN   /home/ivo/CNC-Controller/.tmp_versions
CLEAN   /home/ivo/CNC-Controller/Module.symvers
make[1]: Leaving directory '/usr/src/linux-headers-4.4.0-28-generic'
make -C /lib/modules/4.4.0-28-generic/build M=/home/ivo/CNC-Controller modules
make[1]: Entering directory '/usr/src/linux-headers-4.4.0-28-generic'
CC [M]  /home/ivo/CNC-Controller/CNC_controller.o
In file included from include/linux/printk.h:6:0,
                from include/linux/kernel.h:13,
                from /home/ivo/CNC-Controller/CNC_controller.c:2:
include/linux/kern_levels.h:4:18: error: expected declaration specifiers or ‘...’ before string constant
#define KERN_SOH "\001"  /* ASCII Start Of Header */
                ^
include/linux/kern_levels.h:13:19: note: in expansion of macro ‘KERN_SOH’
#define KERN_INFO KERN_SOH "6" /* informational */
                ^
/home/ivo/CNC-Controller/CNC_controller.c:10:8: note: in expansion of macro ‘KERN_INFO’
printk(KERN_INFO "CNC_controller.c\n");
        ^
In file included from /home/ivo/CNC-Controller/CNC_controller.c:4:0:
/home/ivo/CNC-Controller/axis_controller/axis_controller.h:14:31: warning: ‘axis_controller_get_timer’ declared ‘static’ but never defined [-Wunused-function]
static inline struct hrtimer* axis_controller_get_timer(struct axis_controller* axis_controller);
                            ^
/home/ivo/CNC-Controller/axis_controller/axis_controller.h:16:20: warning: ‘axis_controller_reset_state’ declared ‘static’ but never defined [-Wunused-function]
static inline void axis_controller_reset_state(struct axis_controller* axis_controller);
                    ^
scripts/Makefile.build:264: recipe for target '/home/ivo/CNC-Controller/CNC_controller.o' failed
make[2]: *** [/home/ivo/CNC-Controller/CNC_controller.o] Error 1
Makefile:1403: recipe for target '_module_/home/ivo/CNC-Controller' failed
make[1]: *** [_module_/home/ivo/CNC-Controller] Error 2
make[1]: Leaving directory '/usr/src/linux-headers-4.4.0-28-generic'
Makefile:10: recipe for target 'all' failed
make: *** [all] Error 2
ivo@ivo-Inspiron-5558:~/CNC-Controller$

And this is why I think it isn't compiling because it logs the printk error:

include/linux/kern_levels.h:4:18: error: expected declaration specifiers or ‘...’ before string constant
    #define KERN_SOH "\001"  /* ASCII Start Of Header *

Any clue what I do wrong? because I do what I have seen others are doing ...

Upvotes: 1

Views: 1792

Answers (2)

Alexandre Belloni
Alexandre Belloni

Reputation: 2304

You have two issues:

  • you can't use printk from global scope. This has to be moved to a function.

  • You can't have a C file that has the same name as the module when trying to build a multiple file module. That is, either rename CNC_controller.c or the .ko For example, rename CNC_controller.c CNC_controller_main.c and use:

    CNC_controller-objs := CNC_controller_main.c axis_controller/axis_controller.o

Upvotes: 4

Dimitar
Dimitar

Reputation: 4801

According to the error message, you call a function on top level. Which comes to show that there is a call outside main or another function.

More precisely printk(KERN_INFO "CNC_controller.c\n");.

On a side note #define KERN_SOH "\001" can act only as a stopper, because '\0' is the terminating character. I leave to you to say if that is what you have intended.

Upvotes: 1

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