Hi
I am a Newbie in Kernel Programming and just now subscribed to this list. Writing my first kernel module and reading Alessandro?s book on Linux Device Driver.
When I compile my simple module with gcc, it throughs al bunch of errors.
As far as I think the errors are because the gcc could not find the defination of few of the structure used, like struct file, struct inode and struct file_operations etc. I have included the linux/fs.h file and have also define the required macros like MODULE and __KERNEL__, but still not able to compile it successfully.
For debugging, I ran the macro option (-E) of gcc to get the output of Macro, so that I could know what exactly is included in file before compilation. In the Macro output I could not find the definations of above mentioned structure, although they are defined in linux/fs.h and I have included that file in my source.
I am pasting the output of gcc below.
Also pasting the source of my module.
Please have a look at it and help me if you can.
In source I have left few of the functions like open, release etc, blank. I have just started writing it and will complete it once I get through this problem.
Details of my system:
Single Processor
Redhat Enterprise 3.1
Kernel: linux-2.4.21-4
Compiler : gcc 3.2.3.20
I have one more this to say, when I cteared the simple "Hello World" module and compiled it, it compiled without any problem, but when I tried to load that module in kernel, insmod command gave me versioning error. It said that you are trying to load the module against different kernel version. Well I know it can happen, but my question on this is, is it possible that the runnning kernel might be different from the kernel in source tree. I did not downloaded the source, It?s the default source which comes with installation.
Anyway, please take a look at the errors and source to help me out.
************************************************************************************************
Output of gcc
************************************************************************************************
main.c:27: warning: `struct file' declared inside parameter list
main.c:27: warning: its scope is only this definition or declaration, which is probably not what you want
main.c:27: warning: `struct inode' declared inside parameter list
main.c:28: warning: `struct file' declared inside parameter list
main.c:29: warning: `struct file' declared inside parameter list
main.c:30: warning: `struct file' declared inside parameter list
main.c:31: warning: `struct file' declared inside parameter list
main.c:31: warning: `struct inode' declared inside parameter list
main.c: In function `fifo_init_module':
main.c:71: invalid use of undefined type `struct file_operations'
main.c:72: invalid use of undefined type `struct file_operations'
main.c:73: invalid use of undefined type `struct file_operations'
main.c:73: `write' undeclared (first use in this function)
main.c:73: (Each undeclared identifier is reported only once
main.c:73: for each function it appears in.)
main.c:74: invalid use of undefined type `struct file_operations'
main.c:75: invalid use of undefined type `struct file_operations'
main.c:77: warning: implicit declaration of function `register_chrdev'
main.c:80: warning: implicit declaration of function `printk'
main.c:80: `KERN_EMERG' undeclared (first use in this function)
main.c:80: syntax error before string constant
main.c: In function `fifo_cleanup_module':
main.c:101: warning: implicit declaration of function `unregister_chrdev'
main.c:101: `fifo_f_ops' has an incomplete type
main.c: At top level:
main.c:122: warning: `struct file' declared inside parameter list
main.c:122: warning: `struct inode' declared inside parameter list
main.c:122: conflicting types for `fifo_open'
main.c:27: previous declaration of `fifo_open'
main.c:140: warning: `struct file' declared inside parameter list
main.c:140: conflicting types for `fifo_read'
main.c:28: previous declaration of `fifo_read'
main.c:160: warning: `struct file' declared inside parameter list
main.c:160: conflicting types for `fifo_write'
main.c:29: previous declaration of `fifo_write'
main.c:175: warning: `struct file' declared inside parameter list
main.c:175: conflicting types for `fifo_llseek'
main.c:30: previous declaration of `fifo_llseek'
main.c:194: warning: `struct file' declared inside parameter list
main.c:194: warning: `struct inode' declared inside parameter list
main.c:194: conflicting types for `fifo_release'
main.c:31: previous declaration of `fifo_release'
main.c:203: warning: type defaults to `int' in declaration of `module_init'
main.c:203: warning: parameter names (without types) in function declaration
main.c:203: warning: data definition has no type or storage class
main.c:204: warning: type defaults to `int' in declaration of `module_exit'
main.c:204: warning: parameter names (without types) in function declaration
main.c:204: warning: data definition has no type or storage class
main.c:44: storage size of `fifo_f_ops' isn't known
************************************************************************************************
Main.c
************************************************************************************************
/*Simple FIFO Module*/
#define MODULE
#define __KERNEL__
#include<linux/config.h>
#ifdef CONFIG_SMP
#define __SMP__
#endif
#include<linux/fs.h>
#include<linux/kernel.h>
#include<linux/module.h>
#include<linux/wrapper.h>
#include<linux/types.h>
/*#include<linux/init.h>*/
/*#include<linux/kernel.h>*/
#define MAJOR_NUM 0
#define DRIVER_NAME "my_fifo"
/*========================================
Function Declerations
=========================================*/
int fifo_init_module(void);
void fifo_cleanup_module(void);
int fifo_open(struct inode* fifo_inode_p, struct file* fifo_file_p);
int fifo_read(struct file* fifo_file_p, char* fifo_read_buffer, int fifo_num_char, loff_t* fifo_file_position_p);
size_t fifo_write(struct file* fifo_file_p, char* fifo_write_buffer, size_t fifo_num_char, loff_t* fifo_file_position_p);
int fifo_llseek(struct file* fifo_file_p, loff_t fifo_file_position);
int fifo_release(struct inode* fifo_inode_p, struct file* fifo_file_p);
/*========================================
Global Declerations
=========================================*/
/*struct file_operations fifo_f_ops = {
llseek: fifo_lseek,
read: fifo_read,
write: fifo_write,
open: fifo_open
};*/
struct file_operations fifo_f_ops;
/*this flag will be used for tracking and reverting back
in initialization phase, in case some thing goes wrong in initilizing module*/
int fifo_init_flag = 0;
int fifo_major_num = MAJOR_NUM;
MODULE_PARM(fifo_major_num, "i");
/*========================================
Functions Defination
=========================================*/
/*====================================================================
Name: fifo_init_module()
=====================================================================*/
int fifo_init_module(void){
int retval = 0;
fifo_f_ops.llseek = fifo_llseek;
fifo_f_ops.read = fifo_read;
fifo_f_ops.write = write;
fifo_f_ops.open = fifo_open;
fifo_f_ops.release = fifo_release;
retval = register_chrdev(fifo_major_num, DRIVER_NAME, &fifo_f_ops);
if (retval < 0){
printk(KERN_EMERG "fifo driver could not get the free major number.\n");
return retval;
}
fifo_major_num = fifo_major_num?fifo_major_num:retval;
fifo_init_flag = 1;
}
/*====================================================================
Name: fifo_clear_module()
=====================================================================*/
void fifo_cleanup_module(void){
switch(fifo_init_flag){
case 1:
unregister_chrdev(DRIVER_NAME, fifo_f_ops);
break;
};
}
/*====================================================================
Name: fifo_open()
=====================================================================*/
int fifo_open(struct inode* fifo_inode_p, struct file* fifo_file_p){
}
/*====================================================================
Name: fifo_read()
=====================================================================*/
int fifo_read(struct file* fifo_file_p, char* fifo_read_buffer, int fifo_num_char, loff_t* fifo_file_position_p){
}
/*====================================================================
Name: fifo_write()
=====================================================================*/
size_t fifo_write(struct file* fifo_file_p, char* fifo_write_buffer, size_t fifo_num_char, loff_t* fifo_file_position_p){
}
/*====================================================================
Name: fifo_lseek()
=====================================================================*/
int fifo_llseek(struct file* fifo_file_p, loff_t fifo_file_position){
}
/*====================================================================
Name: fifo_release()
=====================================================================*/
int fifo_release(struct inode* fifo_inode_p, struct file* fifo_file_p){
}
/*====================================================================
Explicitly mentioning the initialization and cleanup function of this
driver module.
=====================================================================*/
module_init(fifo_init_module);
module_exit(fifo_cleanup_module);
Regards,
Gaurav
Do you Yahoo!?
Yahoo! Mail - 50x more storage than other providers!
