I
On Thu, May 7, 2009 at 2:25 PM, Srinivas G.
<srinivasg@xxxxxxxxxxxxxxxxxxxxx> wrote:
> Dear All,
>
> I have written a small sample code for testing the EXPORT_SYMBOL macro
> which exports the symbols to the global kernel symbol table. The sample
> code is working fine in 2.6.9-1.667 kernel version, however it does not
> works fine in 2.6.28 kernel version. I am getting the following errors
> in 2.6.28 kernel version only.
>
If you feel you code is fine.
Then refer to the changelog to verify what changes went in, in context
of your need.
HTH,
> insmod: error inserting 'import_func.ko': -1 Unknown symbol in module
>
> When I see the /var/log/messages through dmesg command, I got the
> following.
>
> import_func: no symbol version for myexportfun
> import_func: Unknown symbol myexportfun
>
> The procedure I used for testing is as follows.
>
> 1) Insert the export_func module as
> insmod export_func.ko
> 2) Check whether the symbols are exported or not
> cat /proc/kallsyms | grep myexp
> 3) The function was exported fine and able to see the names in the
> global kernel symbol table.
> 4) Now, insert the import_func module as
> insmod import_func.ko
>
> Then I got the above errors. But the same code is working fine in
> 2.6.9-1.667 kernel version without any errors. Please some one correct
> me what am I doing wrong.
>
> Thanks in advance.
>
> With Regards,
> Srinivas G
>
> The following C file code exports the symbols to the kernel symbol
> table.
> -------------------------------------------------------------
> #include <linux/init.h> /* for explicit init & exit */
> #include <linux/kernel.h> /* for printk */
> #include <linux/module.h> /* for MODULE_ definitions */
> #include "expfunc.h"
>
> MODULE_AUTHOR("Srinivas G");
> MODULE_LICENSE("GPL");
>
> void myexportfun(void) {
> printk("<%s> I am a exported function - NEW!\n",__FUNCTION__);
> }
>
> EXPORT_SYMBOL(myexportfun);
>
> static int exp_init(void) {
> printk("<%s> Module to demo export of symbols!\n",__FUNCTION__);
> return 0;
> }
>
> static void exp_cleanup(void) {
> printk("<%s> exiting symbol export demo
> module!\n",__FUNCTION__);
> }
>
> module_init(exp_init);
> module_exit(exp_cleanup);
> ---------------------------------------------------------------
> The header file contents are as follows.
>
> #ifndef __EXPFUNC_H
> #define __EXPFUNC_H
>
> //extern void myexportfun(void);
> void myexportfun(void);
>
> #endif
> ----------------------------------------------------------------
> The Makefile contents are as follows.
> #
> # Makefile to export a function name into the kernel symbol table
> # Author: Srinivas G.
> #
> KDIR:=/lib/modules/$(shell uname -r)/build
> TRGT:=export_func
> OBJS:=expfunc.o
>
> EXTRA_CFLAGS +=-DEXPORT_SYMTAB -Wno-unused-variable -Wno-implicit
>
> obj-m += $(TRGT).o
> $(TRGT)-objs := $(OBJS)
>
> default:
> $(MAKE) -C $(KDIR) SUBDIRS=$(PWD) modules
> clean:
> $(MAKE) -C $(KDIR) SUBDIRS=$(PWD) clean
> ---------------------------------------------------------------
> The contents of the import module as follows.
>
> #include <linux/init.h> /* for explicit init & exit */
> #include <linux/kernel.h> /* for printk */
> #include <linux/module.h> /* for MODULE_ definitions */
>
> #include "../export/expfunc.h"
>
> MODULE_AUTHOR("Srinivas G");
> MODULE_LICENSE("GPL");
>
> static int my_init(void) {
> int i;
>
> printk("<%s> Module to demo export of symbols\n",__FUNCTION__);
> myexportfun();
>
> return 0;
> }
>
> static void my_cleanup(void) {
> printk("<%s> exiting symbol export demo module
> \n",__FUNCTION__);
> }
>
> module_init(my_init);
> module_exit(my_cleanup);
> ----------------------------------------------------------------
> The contents of the makefile as follows.
>
> #
> # Makefile for the demo of the import module program
> # Author: Srinivas G.
> #
> KDIR:=/lib/modules/$(shell uname -r)/build
> TRGT:=import_func
> OBJS:=impfunc.o
>
> EXTRA_CFLAGS +=-DEXPORT_SYMTAB -Wno-unused-variable -Wno-implicit
>
> obj-m += $(TRGT).o
> $(TRGT)-objs := $(OBJS)
>
> default:
> $(MAKE) -C $(KDIR) SUBDIRS=$(PWD) modules
> clean:
> $(RM) *.ko *.o *.mod.* .*.cmd -r .tmp*
> ----------------------------------------------------------------
>
>
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>
--
Regards,
Sandeep.
“To learn is to change. Education is a process that changes the learner.”
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