since drop_cache is part of kernel, u have to do 3 things: a. declare EXPORT_SYMBOL() at the end of the fs/drop_caches.c file. b. remove the "static" in front of drop_pagecache() declaration. c. recompile the kernel + modules etc, and reboot into the new kernel. On Tue, Jul 21, 2009 at 12:35 AM, er krishna<erkrishna@xxxxxxxxx> wrote: > > > On Mon, Jul 20, 2009 at 9:54 PM, SandeepKsinha <sandeepksinha@xxxxxxxxx> > wrote: >> >> Hi Krishna, >> >> >> >> On Mon, Jul 20, 2009 at 8:10 PM, er krishna <erkrishna@xxxxxxxxx> wrote: >>> >>> >>> >>> 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. > > dropcache: module license 'unspecified' taints kernel. > dropcache: Unknown symbol drop_slab > dropcache: Unknown symbol drop_pagecache > dropcache: Unknown symbol drop_caches_sysctl_handler > > > Actually what happend I have made some own functiion and put those function > in different files, all of the function from other files are exported easily > but the function from this particular file is not exported due to linking > error. I suspect the entries which it created in System.map file is also not > good. Anybody knows various options of system.map file the please tell me. I > am attaching system.map file . > > >> >> >>> >>> [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 >>> >>> >> > > -- Regards, Peter Teoh -- To unsubscribe from this list: send an email with "unsubscribe kernelnewbies" to ecartis@xxxxxxxxxxxx Please read the FAQ at http://kernelnewbies.org/FAQ
