Re: Creating a file in kernel Module -- working fine

[Shyamjithe <shyamjithe@xxxxxxxxxxxxxxx>]

HI  LIN LOVER
              I THINK YOUR KERNEL IS NOT EXPORTING THOSE SYMBOLS . HOW DID 
YOU  COMPILE THE FILE.
SHYAM

shyamjithe.c.s
Networking & Communications Group
Tata Elxsi Ltd.
(Ph)   +91-471-2527214
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____________________________________

----- Original Message ----- 
From: "linux lover" <linux_lover2004@xxxxxxxxx>
To: "Srinivas G." <srinivasg@xxxxxxxxxxxxxxxxxxxxx>; 
<shyamjithe@xxxxxxxxxxxxxxx>; <bulb@xxxxxx>; <amith@xxxxxxxxxxxxxxx>; 
<karthik301176@xxxxxxxxx>; <gauravd_linux@xxxxxxxxx>; 
<godepankaj@xxxxxxxxxxxxxx>; <J.A.K.Mouw@xxxxxxxxxxxxxxxxx>
Cc: <kernelnewbies@xxxxxxxxxxxx>
Sent: Tuesday, February 22, 2005 10:44 AM
Subject: Re: Creating a file in kernel Module -- working fine


> Hello Srinivas,
>           I am using RedHat 9 with its kernel
> 2.4.20-8 . When i make your program it compiled
> successfully but i am getting following errors while i
> insmod
> insmod cf.o
> cf.o: unresolved symbol sys_open
> cf.o: unresolved symbol sys_write
>
> regards,
> linux_lover.
>
> --- "Srinivas G." <srinivasg@xxxxxxxxxxxxxxxxxxxxx>
> wrote:
>
> > Dear All,
> >
> > I have gone through your mails. Based on those mail
> > messages I have
> > created a test module in the kernel to create a
> > file. It was compiled
> > fine with out any error messages and working fine.
> >
> > I am using Red Hat 7.3 with 2.4.18-3 kernel version.
> > Please fine the
> > code below.
> >
> > cre_fil.c
> ------------------------------------------------------------------
> > #include <linux/kernel.h>
> > #include <linux/module.h>
> > #include <asm/fcntl.h> /* for O_WRONLY */
> > #include <linux/syscall.h> /* for sys_ functions */
> > #include <asm/uaccess.h> /* for set_fs(), get_fs()
> > etc. */
> > #include <linux/string.h> /* for string length */
> > #include <linux/slab.h> /* for kmalloc */
> >
> > MODULE_LICENSE("GPL");
> >
> > typedef struct tagWRITE_TEST
> > {
> > unsigned long fd;
> > unsigned long x;
> >
> > }WRITE_TEST, *PWRITE_TEST;
> >
> > PWRITE_TEST ptest;
> >
> > void SysPrint(char * pString, ...)
> > {
> > static char buff[1024];
> > va_list ap;
> >
> > va_start(ap,pString);
> > vsprintf((char *)buff, pString, ap);
> > va_end(ap);
> >
> > sys_write(ptest->fd,(char *)buff,strlen(buff));
> > }
> >
> > int init_module(void)
> > {
> >
> > printk("<%s> invoked!\n",__FUNCTION__);
> > printk("File Creation Testing in Kernel
> > Module!\n");
> >
> > set_fs(get_ds());
> >
> > /* allocate the memory for structre */
> > ptest =
> > (PWRITE_TEST)kmalloc(sizeof(WRITE_TEST),GFP_KERNEL);
> > if(ptest == NULL)
> > {
> > printk("Structure Memory Allocation Fails!\n");
> > return -ENOMEM;
> > }
> >
> > ptest->fd = sys_open("srcdebug.txt", O_CREAT |
> > O_WRONLY, 644);
> > if (ptest->fd == 0)
> > {
> > printk("File Creation Error!!!\n");
> > return 1;
> > }
> >
> > SysPrint("File Creation Testing in Kernel
> > Module!\n");
> > SysPrint("Srinivas Testing the File Creation\n");
> >
> > /* close the file here */
> > sys_close(ptest->fd);
> >
> > return 0;
> > }
> >
> > void cleanup_module(void)
> > {
> > printk("Good bye!\n");
> >
> > /* free the allocated memory */
> > kfree(ptest);
> >
> > }
> >
> > Makefile
> > ------------------------------------------------
> > INCDIR=/usr/src/linux-2.4/include
> >
> > CFLAGS=-DMODULE -D__KERNEL__ -I$(INCDIR) -O2 -Wall
> >
> > OBJS=cre_fil.o
> > TARGET=cf.o
> >
> > $(TARGET): $(OBJS)
> > $(LD) -r -o $(TARGET) $(OBJS)
> >
> > clean:
> > $(RM) -f $(TARGET) $(OBJS)
> ------------------------------------------------------------------------
> > --
> >
> > I need some information. Where can I get the
> > information for sys_create,
> > sys_write, sys_read, set_fs, get_fs, get_ds etc
> > calls?
> >
> > Please provide any links which are related to that
> > calls or any books.
> >
> > Thanks and regards,
> > Srinivas G
>
>
>
>
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