Writing Your First Linux Driver in the Classroom

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December 1, 2010 132 comments

Device Drivers, Part 2: Writing Your First Linux Driver in theClassroom

This article, which is part of the series on Linux device drivers, deals with the concept ofdynamically loading drivers, first writing a Linux driver, before building and then loading it.

Shweta and Pugs reached their classroom late, to find their professor already in the middleof a lecture. Shweta sheepishly asked for his permission to enter. An annoyed ProfessorGopi responded, Come on! You guys are late again; what is your excuse, today?

Open Source For You

Pugs hurriedly replied that they had been discussing the very topic for that days class device drivers in Linux. Pugs was more than happy when the professor said, Good! Thenexplain about dynamic loading in Linux. If you get it right, the two of you are excused! Pugsknew that one way to make his professor happy was to criticise Windows.

He explained, As we know, a typical driver installation on Windows needs a reboot for it toget activated. That is really not acceptable; suppose we need to do it on a server? Thatswhere Linux wins. In Linux, we can load or unload a driver on the fly, and it is active for useinstantly after loading. Also, it is instantly disabled when unloaded. This is called dynamicloading and unloading of drivers in Linux.

This impressed the professor. Okay! Take your seats, but make sure you are not lateagain. The professor continued to the class, Now you already know what is meant bydynamic loading and unloading of drivers, so Ill show you how to do it, before we move onto write our first Linux driver.

Dynamically loading driversThese dynamically loadable drivers are more commonly called modules and built intoindividual files with a .ko (kernel object) extension. Every Linux system has a standardplace under the root of the file system ( /) for all the pre-built modules. They are organisedsimilar to the kernel source tree structure, under /lib/modules//kernel,where would be the output of the command uname -ron the system, asshown in Figure 1.

Figure 1: Linux pre-built modules

To dynamically load or unload a driver, use these commands, which reside in the /sbindirectory, and must be executed with root privileges:

lsmod lists currently loaded modules

insmod inserts/loads the specified module file

modprobe inserts/loads the module, along with anydependencies

rmmod removes/unloads the module

Lets look at the FAT filesystem-related drivers as an example. Figure 2 demonstrates thiscomplete process of experimentation. The module files would be fat.ko, vfat.ko, etc., inthe fat ( vfat for older kernels) directory under /lib/modules/`uname -r`/kernel/fs. Ifthey are in compressed .gz format, you need to uncompress them with gunzip, beforeyou can insmodthem.

Figure 2: Linux module operations

The vfat module depends on the fat module, so fat.ko needs to be loaded first. Toautomatically perform decompression and dependency loading, use modprobe instead.Note that you shouldnt specify the .ko extension to the modules name, when using themodprobe command. rmmod is used to unload the modules.

Our first Linux driverBefore we write our first driver, lets go over some concepts. A driver never runs by itself. Itis similar to a library that is loaded for its functions to be invoked by a running application.It is written in C, but lacks a main() function. Moreover, it will be loaded/linked with thekernel, so it needs to be compiled in a similar way to the kernel, and the header files youcan use are only those from the kernel sources, not from the standard /usr/include.

One interesting fact about the kernel is that it is an object-oriented implementation in C, aswe will observe even with our first driver. Any Linux driver has a constructor and a

destructor. The modules constructor is called when the module is successfully loaded intothe kernel, and the destructor when rmmod succeeds in unloading the module. These twoare like normal functions in the driver, except that they are specified as the init and exitfunctions, respectively, by the macros module_init() and module_exit(), which aredefined in the kernel header module.h.

/* ofd.c Our First Driver code */

#include

#include

#include

static int __init ofd_init(void) /* Constructor */

{

printk(KERN_INFO "Namaskar: ofd registered");

return 0;

}

static void __exit ofd_exit(void) /* Destructor */

{

printk(KERN_INFO "Alvida: ofd unregistered");

}

module_init(ofd_init);

module_exit(ofd_exit);

MODULE_LICENSE("GPL");

MODULE_AUTHOR("Anil Kumar Pugalia ");

MODULE_DESCRIPTION("Our First Driver");

Given above is the complete code for our first driver; lets call it ofd.c. Note that there isno stdio.h (a user-space header); instead, we use the analogous kernel.h (a kernelspace header). printk() is the equivalent of printf(). Additionally, version.h isincluded for the module version to be compatible with the kernel into which it is going to beloaded. The MODULE_* macros populate module-related information, which acts like themodules signature.

Building our first Linux driverOnce we have the C code, it is time to compile it and create the module file ofd.ko. We usethe kernel build system to do this. The following Makefile invokes the kernels buildsystem from the kernel source, and the kernels Makefile will, in turn, invoke our firstdrivers Makefile to build our first driver.

To build a Linux driver, you need to have the kernel source (or, at least, the kernel headers)installed on your system. The kernel source is assumed to be installed at /usr/src/linux.If its at any other location on your system, specify the location in the KERNEL_SOURCEvariable in this Makefile.

# Makefile makefile of our first driver

# if KERNELRELEASE is defined, we've been invoked from the

# kernel build system and can use its language.

ifneq (${KERNELRELEASE},)

obj-m := ofd.o

# Otherwise we were called directly from the command line.

# Invoke the kernel build system.

else

KERNEL_SOURCE := /usr/src/linux

PWD := $(shell pwd)

default:

${MAKE} -C ${KERNEL_SOURCE} SUBDIRS=${PWD} modules

clean:

${MAKE} -C ${KERNEL_SOURCE} SUBDIRS=${PWD} clean

endif

With the C code ( ofd.c) and Makefile ready, all we need to do is invoke make to build ourfirst driver ( ofd.ko).

$ make

make -C /usr/src/linux SUBDIRS=... modules

make[1]: Entering directory `/usr/src/linux'

CC [M] .../ofd.o

Building modules, stage 2.

MODPOST 1 modules

CC .../ofd.mod.o

LD [M] .../ofd.ko

make[1]: Leaving directory `/usr/src/linux'

Summing upOnce we have the ofd.ko file, perform the usual steps as the root user, or with sudo.

# su

# insmod ofd.ko

# lsmod | head -10

lsmod should show you the ofd driver loaded.

While the students were trying their first module, the bell rang, marking the end of thesession. Professor Gopi concluded, Currently, you may not be able to observe anythingother than the lsmod listing showing the driver has loaded. Wheres the printk outputgone? Find that out for yourselves, in the lab session, and update me with your findings.Also note that our first driver is a template for any driver you would write in Linux. Writing aspecialised driver is just a matter of what gets filled into its constructor and destructor. So,our further learning will be to enhance this driver to achieve specific driver functionalities.

Related Posts:

Device Drivers, Part 17: Module Interactions

Jumpstart Linux Kernel Module Programming

A Simple guide to building your own Linux Kernel

Whats Up in Linux Graphicstopia Lately

The Semester Project-IV File Systems: Formatting a Pen

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montuviky

Away-some post will love to read all (and more :) )

anil_pugalia

Thanks for the appreciation. Go ahead & read all 24 are out in hard form.

vivek

when I run make command, i got the following error

make: Nothing to be done for `default.

I guess it could be the problem because of KERNEL_SOURCE. In my make file i have setKERNEL_SOURCE as follows:

KERNEL_SOURCE := /usr/src/linux-headers-2.6.38-10

the_summer

I had the same problem.For me the problem was copy and pasting the Makefile.Make sure that in front of the ${MAKE} commands is an tab and not multiple spaces.After replacing spaces with tabs it worked for me.

avik

thanks for the solution

the_summer

Just noticed:I dont know if you use *buntu. But KERNEL_SOURCE := /usr/src/linux-headers-2.6.38-10produces some errors.

KERNEL_SOURCE := /usr/src/linux-headers-2.6.38-10-generic seems to work.

Raghu

# Use this file as your Makefile

obj-m +=ofd.o

ofd-objs := ofd.o

all:

make -C /lib/modules/$(shell uname -r)/build M=$(PWD) modules

clean:

make -C /lib/modules/$(shell uname -r)/build M=$(PWD) clean

Raghu

add #include in ofd.c and remove 2nd line from aboveMakefile and compile..

montuviky

I also had the same problem.

So i manually complied it.

make was like

obj-m := ofd.o

and compilation was :

make -C /usr/src/linux-headers-2.6.38-10 SUBDIRS=$PWD modules.

Teja

Thanx bro

akash

hey frnd what does this modules word signify in above make command .do we need to put module path replacing this or directly run above cmmnd as it is reply pls

http://twitter.com/anil_pugalia Anil Pugalia

Its directly the above command as is.

Rakesh Babu

Rakesh babuDynamically load or unload a driver means..


Read the previous article http://www.opensourceforu.com/2010/11/understanding-linux-device-drivers/

Curious_Furious

Where should the C program be placed? In which directory?

In your Makefile, what will be the pwd?

anil_pugalia

In any folder of its own.

PeterHiggs

i liked it :) thanks pugs

http://www.facebook.com/anil.pugalia Anil Pugalia

You are welcome

PeterHiggs

hi pugs, all is well. But I need to know a little more about the Makefile syntax and how itworks line by line I cant digest some code which is alien to me. I would be grateful if youcan throw some light on this.

khamar

wats answer to ur auestion?

http://www.facebook.com/anil.pugalia Anil Pugalia

Try to read up info make

explorer

when ubuntu is installed on desktop

what does /usr/src/ dir contains ? i.e kerner source OR kernel headers?

in my pc linux-headers-2.6.38-10-generic and linux-headers-2.6.38-10 directories are there.what are they.? they dont have any c source . if they are headers why there are twodirectories i.e what is generic means?

anil_pugalia

They are headers. Sources can also be installed in the same folder using apt-get install linux-sources. Two headers are just the two variants created by the particular distro ubuntu here

calixto

its apt-get linux-source

calixto

sorry apt-get install linux-source

anil_pugalia

Thanks for the correction. I also corrected it.

akash

how to check kernel location


I understand you mean the kernel source location. Typically, it would be under /usr/src (linuxor build or ). Also, it may not be installed by default. So, you may have to install it first.

akash

root@ubuntu:/usr/src# make -C /usr/src/linux-headers-3.2.0-29 SUBDIRS=$PWD modules.I run above command & found this error pls help as soon as possible .. pls

make: Entering directory `/usr/src/linux-headers-3.2.0-29

ERROR: Kernel configuration is invalid.include/generated/autoconf.h or include/config/auto.conf are missing.Run make oldconfig && make prepare on kernel src to fix it.

akash

pls reply m waiting


So, as it is mentioned in the above error, do make oldconfig after going into the linux-headers-3.2.0.29 folder.

akash

i was trying to build my driver i got this error :-

root@ubuntu:/home/ayush/device# make -C /usr/src/linux-headers-3.2.0-29-generic-paeSUBDIRS=$PWD modules

make: Entering directory `/usr/src/linux-headers-3.2.0-29-generic-pae


MODPOST 0 modules

make: Leaving directory `/usr/src/linux-headers-3.2.0-29-generic-pae

Pls reply any solution thnx in advance :)


I believe you current directory /home/ayush/device contains the C files which you are tryingto build. And your current kernel configuration is set to build & use drivers, i.e. grepCONFIG_MODULE /usr/src/linux-headers-3.2.0-29-generic-pae/.config should not be not setor empty.

janakiram

I am also facing same problem as mentioned.. its showing

CONFIG_MODULES=y# CONFIG_MODULE_FORCE_LOAD is not setCONFIG_MODULE_UNLOAD=y# CONFIG_MODULE_FORCE_UNLOAD is not setCONFIG_MODULE_SRCVERSION_ALL=y


Use a makefile as suggested in the article. Basically you need the obj-m line for a moduleto be built, i.e. obj-m := ofd.o. So, just giving make on command line may not work.

satheesaran

Great example to start with. Thanks for the article :) Motivates to read more


Those words are really inspiring for me.

yogesh

why every function in the device driver is named as static. As static fuction are not visibleoutside of the file scope. Then, How these driver function gets called by user spaceapplication..

anil_pugalia

You are correct that when static, functions are not visible outside of the file scope, but onlyby their names. Note that, they could be still accessed anywhere by their addresses, andthats what we do with all these driver functions populate their addresses into the structfile_operations and make it available to VFS & hence userspace, through the struct cdev.

manoj

device drivers and its sources of Linux

tushar

when i do make this error comes

please tell solution

sai@ubuntu:~/tushar$ make

make -C /usr/src/linux-headers-3.5.0-17 SUBDIRS=/home/sai/tushar modules

make[1]: Entering directory `/usr/src/linux-headers-3.5.0-17

ERROR: Kernel configuration is invalid.

include/generated/autoconf.h or include/config/auto.conf are missing.

Run make oldconfig && make prepare on kernel src to fix it.

WARNING: Symbol version dump /usr/src/linux-headers-3.5.0-17/Module.symvers

is missing;

modules will have no dependencies and modversions.


/usr/src/linux-headers-3.5.0-17/scripts/Makefile.modpost:42:

include/config/auto.conf: No such file or directory

make[2]: *** No rule to make target `include/config/auto.conf. Stop.

make[1]: *** [modules]

Error 2

make[1]: Leaving directory `/usr/src/linux-headers-3.5.0-17

make: *** [default] Error 2

tushar

please reply i am waiting


Do as the message says: make oldconfigAnd then, make modules_prepareBoth in the linux-headers folder.And then retry.

tushar

1> when i do make oldconfig in linux-headers-3.5..0-17 folder i got this error

HOSTCC scripts/basic/fixdep

scripts/basic/fixdep.c:433:1: fatal error: opening dependency file scripts/basic/.fixdep.d:

Permission denied

compilation terminated.

make[1]: *** [scripts/basic/fixdep] Error 1

make: *** [scripts_basic] Error 2

tushar@Sai:/usr/src/linux-headers-3.5.0-17$

2> and after that if i do make modules_prepare i got this error

HOSTCC scripts/basic/fixdep

scripts/basic/fixdep.c:433:1: fatal error: opening dependency file scripts/basic/.fixdep.d:Permission denied

compilation terminated.

make[2]: *** [scripts/basic/fixdep] Error 1

make[1]: *** [scripts_basic] Error 2

make: *** No rule to make target `modules_prepare. Stop.


i am using ubuntu 12.10kernel version 3.5.0-17-generic

PLZ PROVIDE SOLUTION SIR

tushar

plz reply


Use sudo, yaar.sudo make oldconfig

tushar

1)when i do sudo make oldconfig then it is fine

2) but when i do sudo make modules_prepare i got fooliowing error

tushar@Sai:/usr/src/linux-headers-3.5.0-17$ sudo make modules_prepare

scripts/kconfig/conf silentoldconfig Kconfig

make[1]: *** No rule to make target `/usr/src/linux-headers-3.5.0-

17/arch/x86/syscalls/syscall_32.tbl, needed by`arch/x86/syscalls/../include/generated/asm/unistd_32.h. Stop.

make: *** [archheaders] Error 2


pls tell solution sir


How about sudo make prepare?If not, then some issue with the headers package installation.

Sunil S

hi.. i am facing the same problem Tushar was facing and got exact same error. I desperatelywant to move forward to next tutorial but can get rid of this compile issue

I know u said about headers package. But can you please point out exact issue..

Here is my system info:

Linux sunilshahu 3.5.0-17-generic #28-Ubuntu SMP Tue Oct 9 19:32:08 UTC 2012 i686athlon i686 GNU/Linux

and after doing what you suggested here is the error log i got:

root@sunilshahu:/usr/src/linux-headers-3.5.0-17# make oldconfigHOSTCC scripts/basic/fixdepHOSTCC scripts/kconfig/conf.oSHIPPED scripts/kconfig/zconf.tab.cSHIPPED scripts/kconfig/zconf.lex.cSHIPPED scripts/kconfig/zconf.hash.cHOSTCC scripts/kconfig/zconf.tab.oHOSTLD scripts/kconfig/confscripts/kconfig/conf oldconfig Kconfig## using defaults found in /boot/config-3.5.0-17-generic### configuration written to .config#root@sunilshahu:/usr/src/linux-headers-3.5.0-17#root@sunilshahu:/usr/src/linux-headers-3.5.0-17#root@sunilshahu:/usr/src/linux-headers-3.5.0-17# make preparescripts/kconfig/conf silentoldconfig Kconfigmake[1]: *** No rule to make target `/usr/src/linux-headers-3.5.0-17/arch/x86/syscalls/syscall_32.tbl, needed by`arch/x86/syscalls/../include/generated/asm/unistd_32.h. Stop.

make: *** [archheaders] Error 2root@sunilshahu:/usr/src/linux-headers-3.5.0-17# make preparemake[1]: *** No rule to make target `/usr/src/linux-headers-3.5.0-17/arch/x86/syscalls/syscall_32.tbl, needed by`arch/x86/syscalls/../include/generated/asm/unistd_32.h. Stop.make: *** [archheaders] Error 2

Thanks(it will we while(1){thanks;} if anybody will help to sort this out)

Sunil.

anil_pugalia

Does make modules_prepare also give the same problem? If yes, then as I said earlier, youalso have the some issue with the headers package installation. Try reinstalling the linux-headers package using apt-get.

Sunil S

ok. I did what Ajey said int the above discussion and changed make file as below

KERNEL_SOURCE := /lib/modules/3.5.0-17-generic/build

And it worked.. It compiled the ofd.c and i loaded and unloaded it successfully on my ubuntu12.10.

So, does it means my linux sources or headers are at above directory and not at/usr/src/linux-headers-3.5.0-17-generic and /usr/src/linux-source-3.5.0 , because i tried bothearlier?

anil_pugalia

Typically /lib/modules//build is a link to the corresponding source, these modules are builtfrom making it work with high probability. Please check the link and post here what does itpoint to. That would definitely give insight into this common problem.

Sunil S

hi, i have to change the system after above comment and missed to see the link on thatsystem.

now i am usingLinux sunils 3.2.0-23-generic #36-Ubuntu SMP Tue Apr 10 20:39:51 UTC 2012 x86_64x86_64 x86_64 GNU/Linux

my code compiled with this with make fileobj-m += ofd.oall:make -C /lib/modules/$(shell uname -r)/build M=$(PWD) modulesclean:

make -C /lib/modules/$(shell uname -r)/build M=$(PWD) clean

and when looking at the lib/modules//buld i find as below. but source link(/build/buildd/linux-3.2.0) was red colored(dont know why) and when looking what it pointsto i found that there is no such directory(but still i got my module compiled)

total 1088

drwxr-xr-x 7 root root 4096 Jul 2 13:54 ./

drwxr-xr-x 5 root root 4096 Jun 26 16:05 ../

drwxr-xr-x 3 root root 4096 Apr 25 2012 arch/

lrwxrwxrwx 1 root root 31 May 31 16:57 block -> ../linux-headers-3.2.0-23/block/

-rw-rr 1 root root 140241 Jul 2 13:53 .config

-rw-rr 1 root root 140241 Jul 2 12:25 .config.old

lrwxrwxrwx 1 root root 32 May 31 16:57 crypto -> ../linux-headers-3.2.0-23/crypto/

lrwxrwxrwx 1 root root 39 May 31 16:57 Documentation -> ../linux-headers-3.2.0-23/Documentation/

lrwxrwxrwx 1 root root 33 May 31 16:57 drivers -> ../linux-headers-3.2.0-23/drivers/

lrwxrwxrwx 1 root root 34 May 31 16:57 firmware -> ../linux-headers-3.2.0-23/firmware/

lrwxrwxrwx 1 root root 28 May 31 16:57 fs -> ../linux-headers-3.2.0-23/fs/

drwxr-xr-x 5 root root 4096 Apr 25 2012 include/

lrwxrwxrwx 1 root root 30 May 31 16:57 init -> ../linux-headers-3.2.0-23/init/

lrwxrwxrwx 1 root root 29 May 31 16:57 ipc -> ../linux-headers-3.2.0-23/ipc/

lrwxrwxrwx 1 root root 32 May 31 16:57 Kbuild -> ../linux-headers-3.2.0-23/Kbuild

lrwxrwxrwx 1 root root 33 May 31 16:57 Kconfig -> ../linux-headers-3.2.0-23/Kconfig

drwxr-xr-x 2 root root 4096 Jul 2 12:27 kernel/

lrwxrwxrwx 1 root root 29 May 31 16:57 lib -> ../linux-headers-3.2.0-23/lib/

lrwxrwxrwx 1 root root 34 May 31 16:57 Makefile -> ../linux-headers-3.2.0-23/Makefile

-rw-rr 1 root root 608 Apr 11 2012 .missing-syscalls.d

lrwxrwxrwx 1 root root 28 May 31 16:57 mm -> ../linux-headers-3.2.0-23/mm/

-rw-rr 1 root root 0 Jul 2 11:21 modules.order

-rw-rr 1 root root 791023 Apr 11 2012 Module.symvers

lrwxrwxrwx 1 root root 29 May 31 16:57 net -> ../linux-headers-3.2.0-23/net/

lrwxrwxrwx 1 root root 33 May 31 16:57 samples -> ../linux-headers-3.2.0-23/samples/

drwxr-xr-x 7 root root 4096 Apr 25 2012 scripts/

lrwxrwxrwx 1 root root 34 May 31 16:57 security -> ../linux-headers-3.2.0-23/security/

lrwxrwxrwx 1 root root 31 May 31 16:57 sound -> ../linux-headers-3.2.0-23/sound/

lrwxrwxrwx 1 root root 25 May 31 16:57 source -> /build/buildd/linux-3.2.0

drwxr-xr-x 2 root root 4096 Apr 11 2012 .tmp_versions/

lrwxrwxrwx 1 root root 31 May 31 16:57 tools -> ../linux-headers-3.2.0-23/tools/

lrwxrwxrwx 1 root root 32 May 31 16:57 ubuntu -> ../linux-headers-3.2.0-23/ubuntu/

lrwxrwxrwx 1 root root 29 May 31 16:57 usr -> ../linux-headers-3.2.0-23/usr/

lrwxrwxrwx 1 root root 30 May 31 16:57 virt -> ../linux-headers-3.2.0-23/virt/

anil_pugalia

What output have you sent? Please send the output of:ls -l /lib/modules/`uname -r`/

Sunil S

Here is the output:

root@sunils:~# ls -l /lib/modules/`uname -r`/

total 4276

lrwxrwxrwx 1 root root 39 May 31 16:56 build -> /usr/src/linux-headers-3.2.0-23-generic

drwxr-xr-x 2 root root 4096 Apr 25 2012 initrd

drwxr-xr-x 10 root root 4096 Apr 25 2012 kernel

-rw-rr 1 root root 685840 Apr 25 2012 modules.alias

-rw-rr 1 root root 667167 Apr 25 2012 modules.alias.bin

-rw-rr 1 root root 5724 Apr 11 2012 modules.builtin

-rw-rr 1 root root 7132 Apr 25 2012 modules.builtin.bin

-rw-rr 1 root root 69 Apr 25 2012 modules.ccwmap

-rw-rr 1 root root 314947 Apr 25 2012 modules.dep

-rw-rr 1 root root 463653 Apr 25 2012 modules.dep.bin

-rw-rr 1 root root 186 Apr 25 2012 modules.devname

-rw-rr 1 root root 889 Apr 25 2012 modules.ieee1394map

-rw-rr 1 root root 295 Apr 25 2012 modules.inputmap

-rw-rr 1 root root 4624 Apr 25 2012 modules.isapnpmap

-rw-rr 1 root root 1421 Apr 25 2012 modules.ofmap

-rw-rr 1 root root 128682 Apr 11 2012 modules.order

-rw-rr 1 root root 451186 Apr 25 2012 modules.pcimap

-rw-rr 1 root root 2815 Apr 25 2012 modules.seriomap

-rw-rr 1 root root 131 Apr 25 2012 modules.softdep

-rw-rr 1 root root 260900 Apr 25 2012 modules.symbols

-rw-rr 1 root root 330555 Apr 25 2012 modules.symbols.bin

-rw-rr 1 root root 998947 Apr 25 2012 modules.usbmap

anil_pugalia

I hope that clarifies all the doubts. The link is correctly pointing to the headers, which areworking for you. Pasting it here for reference:lrwxrwxrwx 1 root root 39 May 31 16:56 build -> /usr/src/linux-headers-3.2.0-23-generic

[email protected]

I use your code and compile successfully.But when insmod by sudo insmod ofd.ko, error prompt- insmod: error inserting ofd.ko': -1Invalid module format.Can you tell me why?Thx.


Make sure that the kernel headers you used to compile the driver has the same version asthe running kernel.

[email protected]

I change the KERNEL_SOURCE to /lib/module/$(shell uname -r)/build.It is ok right now.

tushraj

I use your code and compile by make command then i got following error

tushar@tushar-SVE14112ENW:~/devdrv$ makemake -C /usr/src/linux-headers-3.5.0-17 SUBDIRS=/home/tushar/devdrv modulesmake[1]: Entering directory `/usr/src/linux-headers-3.5.0-17WARNING: Symbol version dump /usr/src/linux-headers-3.5.0-17/Module.symvers ismissing;modules will have no dependencies and modversions.Building modules, stage 2.

MODPOST 0 modules

/bin/sh: 1: scripts/mod/modpost: not found

make[2]: *** [__modpost] Error 127

make[1]: *** [modules] Error 2

make[1]: Leaving directory `/usr/src/linux-headers-3.5.0-17

make: *** [default] Error 2


Check out the comments below for the solution to the same problem.

enigma

obj-m := ofd.o should be obj-m += ofd.o ?


In this particular case, even := is fine as, we are limiting the build to the drivers directory andmore to our driver, alone.

janakiram

I use your code and compile by make command then i got following errors

make -C /usr/src/linux-headers-3.2.0-29 SUBDIRS=/home/shivaram/jani modulesmake[1]: Entering directory `/usr/src/linux-headers-3.2.0-29

ERROR: Kernel configuration is invalid.include/generated/autoconf.h or include/config/auto.conf are missing.Run make oldconfig && make prepare on kernel src to fix it.

WARNING: Symbol version dump /usr/src/linux-headers-3.2.0-29/Module.symversis missing; modules will have no dependencies and modversions.

Building modules, stage 2./usr/src/linux-headers-3.2.0-29/scripts/Makefile.modpost:42: include/config/auto.conf: Nosuch file or directorymake[2]: *** No rule to make target `include/config/auto.conf. Stop.make[1]: *** [modules] Error 2make[1]: Leaving directory `/usr/src/linux-headers-3.2.0-29make: *** [default] Error 2s

And also i tried with make oldconfig&&make prepare then i got problem like

make: *** No rule to make target `oldconfig. Stop.

i installed ubuntu through vmware. one of my friend said its the problem u should installnormal way..


Check out the discussion threads below.

uday

sir,i have created a makefile and added obj-m := ofd.o in it.

After saving and exiting the terminal,i have given command like this

make -C /usr/src/linux-headers-generic-pae-3.2.0-12 SUBDIRS=$PWD modules

but it is showing no rule to makepls help me.regards,uday.


Make sure that you use *only tabs* to indent your makefile. You get such errors, if you haveused spaces instead.

Ajey

Namaste, When I used Kernel_Source as KERNEL_SOURCE := /usr/src/linux-header-3.5.0-30-generic > I get an error No such file or directory and when I change Kernel_Source asKERNEL_SOURCE := /lib/modules/3.5.0-30-generic/build (this was recommended in one ofcomments below), then I get following error. Not able to proceed beyond this .

make -C /lib/modules/3.5.0-30-generic/build SUBDIRS=/ modulesmake[1]: Entering directory `/usr/src/linux-headers-3.5.0-30-genericscripts/Makefile.build:128: kbuild: Makefile.build is included improperlymake[2]: *** No rule to make target `kernel/bounds.c, needed by `kernel/bounds.s. Stop.make[1]: *** [_module_] Error 2make[1]: Leaving directory `/usr/src/linux-headers-3.5.0-30-genericmake: *** [default] Error 2

anil_pugalia

Seems like, there is some problem with the installation of the kernel headers with thisversion of the distro you are using.

xpress_embedo

I too got this error, the problem was that I had created a folder Linux Device Driver and underthis HelloWorld, When i remove Space and Change Folder name as LinuxDeviceDriver,everything works fine, Hoping you too had done same thing.Hope this help.

Very Nice Tutorial:-)

anil_pugalia

Oh! Thats great input. Hey guys, please fix your problems, if you are having the sameproblem.

Ajey

After I upgraded to Ubuntu 13.04, the problem got rectified, only thing is, in the sampleMakefile, I had to change Kernel_Source := /lib/modules//3.8.0-23-generic/build. Thanks forthis article.

anil_pugalia

You are welcome.

nandan

Thanks sir ..you have done a great job.

anil_pugalia

Thanks for reading & appreciating.

nbtsos

hi sir, i can compile on ubuntu version 8, but when i use ubuntu 12.04 lts, i tried every way tocompile but still cannot compile:user@ubuntu:~/Study$ makemake: Nothing to be done for `default.

Then i add default: ofd.o to our Makefile but it raise another error:cc -c -o ofd.o ofd.cofd.c:2:26: fatal error: linux/module.h: No such file or directory compilation terminated.

Later, i must use command (type manually to terminal) like this to compile :make -C /lib/modules/3.5.0-37-generic/build SUBDIRS=/home/user/Study modules

And the result is OK:make: Entering directory `/usr/src/linux-headers-3.5.0-37-genericCC [M] /home/nobita/Study/ofd.oBuilding modules, stage 2.MODPOST 1 modulesCC /home/nobita/Study/ofd.mod.oLD [M] /home/nobita/Study/ofd.komake: Leaving directory `/usr/src/linux-headers-3.5.0-37-generic

Could you help me how to handle this, and why cant i use Makefile??Thanks in advance!

nbtsos

And there is a slight problem here, when using Ubuntu 8.x (kernel 2.6x) with your Makefile,everything ok. When insmod -> dmesg -> get line Namaskar: ofcd registered, when rmmod -> dmesg -> get line Alvida: ofcd unregistered. But with ubuntu 12.04 LTS (kernel 3.5x),compile with method state above, when When insmod -> dmesg -> nothing, but when rmmod-> dmesg -> get 2 line Namaskar and Alvida

anil_pugalia

Thanks for your appreciation, as well.

Ajay

Hi sir,I am getting there error plz help me out

ajay@ubuntu:~/module$ makemake -C /usr/src/linux-headers-3.5.0-17-generic SUBDIRS-/home/ajay/module modulemake[1]: Entering directory `/usr/src/linux-headers-3.5.0-17-genericHOSTCC scripts/basic/fixdepscripts/basic/fixdep.c:433:1: fatal error: opening dependency file scripts/basic/.fixdep.d:Permission deniedcompilation terminated.make[3]: *** [scripts/basic/fixdep] Error 1make[2]: *** [scripts_basic] Error 2make[1]: *** No rule to make target `SUBDIRS-/home/ajay/module. Stop.make[1]: Leaving directory `/usr/src/linux-headers-3.5.0-17-genericmake: *** [all] Error 2

anil_pugalia

I hope pjms comment as mentioned above, has solved your problem.

Ajay

Hi sir,I am getting there error plz help me out

ajay@ubuntu:~/module$ makemake -C /usr/src/linux-headers-3.5.0-17-generic SUBDIRS-/home/ajay/module modulemake[1]: Entering directory `/usr/src/linux-headers-3.5.0-17-genericHOSTCC scripts/basic/fixdepscripts/basic/fixdep.c:433:1: fatal error: opening dependency file scripts/basic/.fixdep.d:Permission deniedcompilation terminated.make[3]: *** [scripts/basic/fixdep] Error 1make[2]: *** [scripts_basic] Error 2make[1]: *** No rule to make target `SUBDIRS-/home/ajay/module. Stop.make[1]: Leaving directory `/usr/src/linux-headers-3.5.0-17-genericmake: *** [all] Error 2

pjmpjm

peter@Ubuntu2:~$peter@Ubuntu2:~$ rm ofd.mod.opeter@Ubuntu2:~$ rm ofd.ko

peter@Ubuntu2:~$peter@Ubuntu2:~$ make -f makefilemake: Nothing to be done for `default.peter@Ubuntu2:~$ make -f Makefilemake -C /usr/src/linux-headers-3.2.0-56-generic SUBDIRS=/home/peter modulesmake[1]: Entering directory `/usr/src/linux-headers-3.2.0-56-genericBuilding modules, stage 2.MODPOST 1 modulesCC /home/peter/ofd.mod.oLD [M] /home/peter/ofd.komake[1]: Leaving directory `/usr/src/linux-headers-3.2.0-56-genericpeter@Ubuntu2:~$

makefile( indented lines have 4 leading spaces using cut&paste from this article)

ifneq (${KERNELRELEASE},)obj-m := ofd.o# Otherwise we were called directly from the command line.# Invoke the kernel build system.elseKERNEL_SOURCE := /usr/src/linux-headers-3.2.0-56-genericPWD := $(shell pwd)default:${MAKE} -C ${KERNEL_SOURCE} SUBDIRS=${PWD} modules

clean:${MAKE} -C ${KERNEL_SOURCE} SUBDIRS=${PWD} cleanendif

Makefile ( indented lines have 1 leading tab after editing)

ifneq (${KERNELRELEASE},)obj-m := ofd.o# Otherwise we were called directly from the command line.# Invoke the kernel build system.elseKERNEL_SOURCE := /usr/src/linux-headers-3.2.0-56-genericPWD := $(shell pwd)default:${MAKE} -C ${KERNEL_SOURCE} SUBDIRS=${PWD} modules

clean:${MAKE} -C ${KERNEL_SOURCE} SUBDIRS=${PWD} cleanendif

Sooooooo if you cut and paste from this tutorial to create your makefile edit it so that theleading white space is one Tab this is with Ububtu 12.04

hope this helps

nice work Anil

pjm

anil_pugalia

Thanks pjm.

Sham

Hello,

I am trying to compile USB driver code, but getting followingwarnings:

root@ubuntu:/opt/linux-cortexm-1.4.1/projects/developer/app/driver#makemake -C /opt/linux-cortexm-1.4.1/linux M=`pwd` modules CFLAGS=LDFLAGS=make[1]: Entering directory `/opt/linux-cortexm-1.4.1/linuxCC [M] /opt/linux-cortexm-1.4.1/projects/developer/app/driver/vcom.oBuilding modules, stage 2.MODPOST 1 modulesWARNING: usb_register_driver[/opt/linux-cortexm-1.4.1/projects/developer/app/driver/vcom.ko]undefined!WARNING: usb_register_dev[/opt/linux-cortexm-1.4.1/projects/developer/app/driver/vcom.ko]undefined!WARNING: usb_get_dev[/opt/linux-cortexm-1.4.1/projects/developer/app/driver/vcom.ko]undefined!WARNING: usb_put_dev[/opt/linux-cortexm-1.4.1/projects/developer/app/driver/vcom.ko]undefined!WARNING: usb_deregister_dev[/opt/linux-cortexm-1.4.1/projects/developer/app/driver/vcom.ko]undefined!WARNING: usb_find_interface[/opt/linux-cortexm-1.4.1/projects/developer/app/driver/vcom.ko]undefined!WARNING: usb_bulk_msg[/opt/linux-cortexm-1.4.1/projects/developer/app/driver/vcom.ko]undefined!WARNING: usb_deregister[/opt/linux-cortexm-1.4.1/projects/developer/app/driver/vcom.ko]undefined!CC /opt/linux-cortexm-1.4.1/projects/developer/app/driver/vcom.mod.oLD [M]

/opt/linux-cortexm-1.4.1/projects/developer/app/driver/vcom.komake[1]: Leaving directory `/

Date post:	06-Nov-2015
Category:	Documents
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