On Mon, Jul 20, 2009 at 8:10 PM, er krishna <erkrishna@xxxxxxxxx> wrote:
Do a dmesg and provide the results?
You will see that which symbol still remains unresolved. May be you need to export some more of them.
Regards,
Sandeep.
“To learn is to change. Education is a process that changes the learner.”
Dear All,
I have one simple problem in exporting the function. Everything is fine, but its not working as per the expectation. Actually I have to export some function from fs/dropcache.c, but it is not working as per the expectataion, [ I am able to export any function from other files like fs/buffer.c and block/genhd.c but dropcache.c creates a problem] .I am attaching the file. Just once check & please tell if something is missing, what I have done is as follows:
I have exported three functions from fs/dropcaches.c by making their function declaration in linux/mm.h, compiled the corresponding 2.6.26 kernel & got their entries in System.map file as follows:
c0174d98 T drop_slab
c0174db2 T drop_pagecache
c0174ea7 T drop_caches_sysctl_handler
These entries are quite different from the actual exported functions from other files, it has only T option. Can antbody elaborate what is the meaning of these options like T, t, r , u and so on?
I have booted with same 2.6.26 kernel. I included linux/mm.h and all the above three function in my module done make & found following warnings in compilation & following error message in insmod due to some linking error:
[root@CENTOS2 kernel]# make
make -C /lib/modules/2.6.26/build M=/root/kernel modules
make[1]: Entering directory `/root/Desktop/linux-2.6.26'
Building modules, stage 2.
MODPOST 2 modules
WARNING: "drop_slab" [/root/kernel/dropcache.ko] undefined!
WARNING: "drop_pagecache" [/root/kernel/dropcache.ko] undefined!
WARNING: "drop_caches_sysctl_handler" [/root/kernel/dropcache.ko] undefined!
make[1]: Leaving directory `/root/Desktop/linux-2.6.26'
[root@CENTOS2 kernel]#
[root@CENTOS2 kernel]#
[root@CENTOS2 kernel]# insmod dropcache.ko
insmod: error inserting 'dropcache.ko': -1 Unknown symbol in module
Do a dmesg and provide the results?
You will see that which symbol still remains unresolved. May be you need to export some more of them.
[root@CENTOS2 kernel]#
[root@CENTOS2 kernel]#
Any idea how to trace it & what is missing, as I got all the exported entries in System.map file & I have included the function declaration file linux/mm.h on the same compiled kernel, it should do the things in right manner.
Please suggest, If I am missing something or you want any more information. I am attaching my kernel module and these are some more snippet :
[root@CENTOS2 kernel]# uname -a
Linux CENTOS2 2.6.26 #1 SMP Sun Jul 19 10:54:05 IST 2009 i686 i686 i386 GNU/Linux
[root@CENTOS2 kernel]#
[root@CENTOS2 kernel]# tail -1 /root/Desktop/linux-2.6.26/fs/drop_caches.c
EXPORT_SYMBOL(drop_caches_sysctl_handler);
[root@CENTOS2 kernel]#
[root@CENTOS2 kernel]#
Regards,
Sandeep.
“To learn is to change. Education is a process that changes the learner.”
Thanks and Best Regards,
------------------------
Krishna Kumar
