외부 모듈로 빌드하면 Linux Char 장치 드라이버가 작동하지 않지만 커널을 실행하지 않는 경우 빌드하면 작동합니다.하지만 그 이유는 무엇입니까?

Question

OS : 페도라 26 알파

커널 : 리눅스 4.11

커널은 수동으로 다음과 같은 명령으로 컴파일 :

1)

3) 모든 만들 menuconfig를 만드는)

2 oldconfig하기

4) make module_install

5)

성공적으로 커널 컴파일과 최신의 설치 후

, 내가 몇 가지 모듈을 빌드, 설치하게하지만 make -C /root/linux-4.11/ M=$(pwd) modules를 통해 외부 모듈로하지 커널을 실행에있다. 내가 개발 한 모든 기본 모듈은 예상대로 컴파일 및 설치되고 작동하지만 기본 문자 장치 드라이버를 코딩하지만 일부 이상한 문제가 발견되었습니다. 즉, insmod을 통해 모듈을 성공적으로 컴파일하고 삽입 한 후,이 모듈에 관한 커널 메시지를 얻지 못했고/dev/디렉토리에 문자 장치가 생성되지 않았지만이 문제에 관해서도 검색했지만 개선되지는 않았습니다. 이 같은 문제에 대한 대답.

갑자기 내가 컴파일하려고 시도하고 모듈을 삽입 한 후 make -C /lib/modules/$(uname -r)/build/ M=$(pwd) modules을 통해 커널을 실행하면서 내 기대 결과를 얻는다. 하지만 외부 모듈로 빌드 할 때 다른 간단한 모듈이 제대로 작동하기 때문에 왜 이런 일이 발생하는지 파악하고 싶습니다.하지만 왜이 모듈을 사용하지 않을까요?

#include <linux/init.h> 
#include <linux/module.h> 
#include <linux/kernel.h> 
#include <linux/device.h> 
#include <linux/kdev_t.h> 
#include <linux/uaccess.h> 
#include <linux/types.h> 
#include <linux/fs.h> 
#include <linux/cdev.h> 
#include <linux/version.h> 

MODULE_LICENSE("GPL"); 
MODULE_AUTHOR("Neeraj Pal <xyz@gmail.com>"); 
MODULE_DESCRIPTION("Sample Character Driver"); 


static dev_t first; 
static struct device *dev_ret; 
static struct cdev c_dev; 
static struct class *cl; 


static int dev_open(struct inode *,struct file *); 
static int dev_release(struct inode *,struct file *); 
static ssize_t dev_read(struct file *, char __user *,size_t count, loff_t *); 
static ssize_t dev_write(struct file *, const char __user *,size_t count, loff_t *); 

static struct file_operations fops = { 
    .owner = THIS_MODULE, 
    .open = dev_open, 
    .read = dev_read, 
    .write = dev_write, 
    .release = dev_release 
}; 

static int __init chardev_init(void) 
{ 
    int ret; 
    printk(KERN_ALERT "char device registered\n"); 
    if ((ret = alloc_chrdev_region(&first,0,1,"Namastey")) < 0) 
    { 
     return ret; 
    } 
    if (IS_ERR(cl = class_create(THIS_MODULE,"hello"))) 
    { 
     unregister_chrdev_region(first,1); 
     return PTR_ERR(cl); 
    } 
    if (IS_ERR(dev_ret = device_create(cl,NULL,first,NULL,"mychar"))) 
    { 
     class_destroy(cl); 
     unregister_chrdev_region(first,1); 
     return PTR_ERR(dev_ret); 
    } 

    cdev_init(&c_dev,&fops); 

    if ((ret = cdev_add(&c_dev, first, 1)) < 0) 
    { 
     device_destroy(cl, first); 
     class_destroy(cl); 
     unregister_chrdev_region(first, 1); 
     return ret; 
    } 
    return 0; 
} 

static void __exit chardev_exit(void) 
{ 
    cdev_del(&c_dev); 
    device_destroy(cl, first); 
    class_destroy(cl); 
    unregister_chrdev_region(first, 1); 
    printk(KERN_INFO " Unloaded \n"); 
} 


static int dev_open(struct inode *i, struct file *f) 
{ 
    printk(KERN_INFO "Driver: open()\n"); 
    return 0; 
} 
static int dev_release(struct inode *i, struct file *f) 
{ 
    printk(KERN_INFO "Driver: close()\n"); 
    return 0; 
} 
static ssize_t dev_read(struct file *f, char __user *buf, size_t len, loff_t *off) 
{ 
    printk(KERN_INFO "Driver: read()\n"); 
    return 0; 
} 
static ssize_t dev_write(struct file *f, const char __user *buf, size_t len, 
    loff_t *off) 
{ 
    printk(KERN_INFO "Driver: write()\n"); 
    return len; 
} 


module_init(chardev_init); 
module_exit(chardev_exit); 

컴파일 & 커널 로그 & 커널, OS 정보 (외부 모듈로 모두 다음 커널을 실행에 대한 등) :

[root@localhost ldd]# uname -a 
Linux localhost.localdomain 4.11.0 #1 SMP Tue May 2 14:34:09 IST 2017 x86_64 x86_64 x86_64 GNU/Linux 
[root@localhost ldd]# 
#NOW,BUILD as external module 
[root@localhost ldd]# make -C /root/linux-4.11/ M=$(pwd) modules 
make: Entering directory '/root/linux-4.11' 

    WARNING: Symbol version dump ./Module.symvers 
      is missing; modules will have no dependencies and modversions. 

    Building modules, stage 2. 
    MODPOST 1 modules 
make: Leaving directory '/root/linux-4.11' 
[root@localhost ldd]# insmod char 
char_driver/ char.ko  char.mod.o char.o  
[root@localhost ldd]# insmod char.ko 
insmod: ERROR: could not insert module char.ko: File exists 
[root@localhost ldd]# rmmod char 
[root@localhost ldd]# insmod char.ko 
[root@localhost ldd]# journalctl -n 10 
-- Logs begin at Tue 2017-05-02 11:28:36 IST, end at Fri 2017-05-05 12:14:01 IST. -- 
May 05 12:12:11 localhost.localdomain systemd[1]: Started Network Manager Script Dispatcher Service. 
May 05 12:12:11 localhost.localdomain nm-dispatcher[1356]: req:1 'dhcp4-change' [ens3]: new request (4 scripts) 
May 05 12:12:11 localhost.localdomain nm-dispatcher[1356]: req:1 'dhcp4-change' [ens3]: start running ordered scripts... 
May 05 12:12:11 localhost.localdomain dhclient[564]: bound to xxx.xxx.xxx.xx-- renewal in 1401 seconds. 
May 05 12:12:21 localhost.localdomain audit[1]: SERVICE_STOP pid=1 uid=0 auid=4294967295 ses=4294967295 msg='unit=NetworkManager-dispatcher comm="syst 
May 05 12:14:01 localhost.localdomain anacron[1345]: Job `cron.daily' started 
May 05 12:14:01 localhost.localdomain run-parts[1377]: (/etc/cron.daily) starting logrotate 
May 05 12:14:01 localhost.localdomain run-parts[1382]: (/etc/cron.daily) finished logrotate 
May 05 12:14:01 localhost.localdomain anacron[1345]: Job `cron.daily' terminated 
May 05 12:14:01 localhost.localdomain anacron[1345]: Normal exit (1 job run) 
[root@localhost ldd]# uname -a;cat /etc/redhat-release ;cat Makefile 
Linux localhost.localdomain 4.11.0 #1 SMP Tue May 2 14:34:09 IST 2017 x86_64 x86_64 x86_64 GNU/Linux 
Fedora release 26 (Twenty Six) 
obj-m := char.o 

[root@localhost ldd]# make -C /lib/modules 
modules/  modules-load.d/ 
[root@localhost ldd]# make -C /lib/modules/4.11.0 
4.11.0/       4.11.0-0.rc3.git0.2.fc26.x86_64/ 
[root@localhost ldd]# make -C /lib/modules/4.11.0/ 
build/ kernel/ source/ 
#Now, Build against running kernel 
[root@localhost ldd]# make -C /lib/modules/4.11.0/build/ M=$(pwd) modules 
make: Entering directory '/usr/src/linux-4.11' 
    CC [M] /root/ldd/char.o 
    Building modules, stage 2. 
    MODPOST 1 modules 
    CC  /root/ldd/char.mod.o 
    LD [M] /root/ldd/char.ko 
make: Leaving directory '/usr/src/linux-4.11' 
[root@localhost ldd]# rmmod char 
[root@localhost ldd]# insmod char.ko 
[root@localhost ldd]# journalctl -n 10 
-- Logs begin at Tue 2017-05-02 11:28:36 IST, end at Fri 2017-05-05 12:33:04 IST. -- 
May 05 12:12:11 localhost.localdomain nm-dispatcher[1356]: req:1 'dhcp4-change' [ens3]: new request (4 scripts) 
May 05 12:12:11 localhost.localdomain nm-dispatcher[1356]: req:1 'dhcp4-change' [ens3]: start running ordered scripts... 
May 05 12:12:11 localhost.localdomain dhclient[564]: bound to xxx.xxx.xxx.xx-- renewal in 1401 seconds. 
May 05 12:12:21 localhost.localdomain audit[1]: SERVICE_STOP pid=1 uid=0 auid=4294967295 ses=4294967295 msg='unit=NetworkManager-dispatcher comm="syst 
May 05 12:14:01 localhost.localdomain anacron[1345]: Job `cron.daily' started 
May 05 12:14:01 localhost.localdomain run-parts[1377]: (/etc/cron.daily) starting logrotate 
May 05 12:14:01 localhost.localdomain run-parts[1382]: (/etc/cron.daily) finished logrotate 
May 05 12:14:01 localhost.localdomain anacron[1345]: Job `cron.daily' terminated 
May 05 12:14:01 localhost.localdomain anacron[1345]: Normal exit (1 job run) 
May 05 12:33:04 localhost.localdomain kernel: char device registered 
[root@localhost ldd]# ls -la /dev/mychar 
crw------- 1 root root 244, 0 May 5 12:33 /dev/mychar 
[root@localhost ldd]# echo "" > /dev/mychar 
[root@localhost ldd]# cat /dev/mychar 
[root@localhost ldd]# rmmod char 
[root@localhost ldd]# journalctl -n 10 
-- Logs begin at Tue 2017-05-02 11:28:36 IST, end at Fri 2017-05-05 12:33:57 IST. -- 
May 05 12:14:01 localhost.localdomain anacron[1345]: Job `cron.daily' terminated 
May 05 12:14:01 localhost.localdomain anacron[1345]: Normal exit (1 job run) 
May 05 12:33:04 localhost.localdomain kernel: char device registered 
May 05 12:33:40 localhost.localdomain kernel: Driver: open() 
May 05 12:33:40 localhost.localdomain kernel: Driver: write() 
May 05 12:33:40 localhost.localdomain kernel: Driver: close() 
May 05 12:33:51 localhost.localdomain kernel: Driver: open() 
May 05 12:33:51 localhost.localdomain kernel: Driver: read() 
May 05 12:33:51 localhost.localdomain kernel: Driver: close() 
May 05 12:33:57 localhost.localdomain kernel: Unloaded 

또한 위의 로그 및 출력 아래 가능한 스크린 샷을 볼 수 있습니다 자세한 내용은 (당신이 텍스트 정보에 만족하지 않는 경우, 링크를 클릭) :

Build against external module (not working,don't know why and Kernel & OS Details and Makefile

Build against running kernel (working , don't know why)

Answer 1

누락 된 Module.symvers에 대한 경고는 빌드중인 커널에 CONFIG_MODVERSIONS 옵션이 없음을 나타냅니다. 때로는로드 모듈을 다른 커널에 맞게 구축하려면이 옵션을 활성화해야합니다. 빌드중인 커널 소스가 완전히 컴파일되지 않았고 파일이 아직 생성되지 않은 경우에도 문제가 발생할 수 있습니다.