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How to compile linux kernel module

Want to compile a linux kernel module. Start to work on it from a simple hello example, here is error info:
$ make hello
cc hello.c -o hello
hello.c:1:60: error: linux/module.h: No such file or directory
hello.c:3:60: error: linux/init.h: No such file or directory
hello.c:5: error: expected =, ,, ;, asm or __attribute__ before hello_start
hello.c:12: error: expected =, ,, ;, asm or __attribute__ before hello_end
hello.c:17: warning: data definition has no type or storage class
hello.c:17: warning: parameter names (without types) in function declaration
hello.c:18: warning: data definition has no type or storage class
hello.c:18: warning: parameter names (without types) in function declaration
make: *** [hello] Error 1
--------------------------------
What 's wrong with it? Looking forwards to hear from experts.

hello.c
#include <linux/module.h>       /* Needed by all modules */
#include <linux/kernel.h>       /* Needed for KERN_INFO */
#include <linux/init.h>         /* Needed for the macros */
 
static int __init hello_start(void)
{
printk(KERN_INFO "Loading hello module...\n");
printk(KERN_INFO "Hello world\n");
return 0;
}
 
static void __exit hello_end(void)
{
printk(KERN_INFO "Goodbye Mr.\n");
}
 
module_init(hello_start);
module_exit(hello_end);
 
Makefile:
obj-m = hello.o
KVERSION = $(shell uname -r)
all:
        make -C /lib/modules/$(KVERSION)/build M=$(PWD) modules
clean:
        make -C /lib/modules/$(KVERSION)/build M=$(PWD) clean

Open in new window

ravenpl

Do You have installed "kernel-devel" package?
yum install kernel-devel

also, it may happen, that the running kernel and kernel-devel version differ - boot to proper kernel then, or change the
KVERSION = $(shell uname -r)
to
KVERSION = 2.6.27.19-170.2.35.fc10.i686 # change to kernel-devel package version

jl66

ASKER

I installed the kernel-devel package, whose version is different from the fedora 10 binary version. Could you please elaborate your solution in detail?
In which file can I change the KVERSION?

ravenpl

> In which file can I change the KVERSION?
In the makefile You provided.
say
# rpm -q kernel-devel # says
kernel-devel-2.6.27.19-170.2.35.fc10.i686
then edit the Makefile and change the KVERSION. Of course module compiled for kernel other than running will not load to this kernel.

jl66

ASKER

I copied the Makefile. Do you think it makes sense in Fedora 10? If not, do you have a good example for it?

jl66

ASKER

It does not seem working:
$ cat Makefile
obj-m = hello.o
KVERSION = 2.6.27.19-170.2.35.fc10.i686
all:
make -C /lib/modules/$(KVERSION)/build M=$(PWD) modules
clean:
make -C /lib/modules/$(KVERSION)/build M=$(PWD) clean
[jeff@localhost demo]$ make hello
cc hello.c -o hello
hello.c:1:60: error: linux/module.h: No such file or directory
hello.c:3:60: error: linux/init.h: No such file or directory
hello.c:5: error: expected =, ,, ;, asm or __attribute__ before hello_start
hello.c:12: error: expected =, ,, ;, asm or __attribute__ before hello_end
hello.c:17: warning: data definition has no type or storage class
hello.c:17: warning: parameter names (without types) in function declaration
hello.c:18: warning: data definition has no type or storage class
hello.c:18: warning: parameter names (without types) in function declaration
make: *** [hello] Error 1

What else can I try?

ravenpl

try issuing just
make

jl66

ASKER

Still can't make it.
$ cat Makefile
obj-m = hello.o
KVERSION = 2.6.27.19-170.2.35.fc10.i686
all:
make -C /lib/modules/$(KVERSION)/build M=$(PWD) modules
clean:
make -C /lib/modules/$(KVERSION)/build M=$(PWD) clean
[jeff@localhost demo]$ make
make: Nothing to be done for `all'.

ravenpl

I suppose You are lacking the <tab> char before make in the Makefile, use the attached one.

Makefile

jl66

ASKER

I used your makefile to make hello module, but it still failed.
[jeff@localhost demo]$ make
make -C /lib/modules/2.6.27.19-170.2.35.fc10.i686/build M=/home/jeff/demo modules
make: *** /lib/modules/2.6.27.19-170.2.35.fc10.i686/build: No such file or directory. Stop.
make: *** [all] Error 2

I checked I could not find the directory /lib/modules/2.6.27.19-170.2.35.fc10.i686. Should we have to make a link? BTW, did you test the Makefile in your system? How did it go?

SOLUTION

ravenpl

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jl66

ASKER

I downloaded the source code linux-2.6.29.tar.bz2. Could you point me to a link on how to load the new source in or list the steps I can follow for it? I found so many links, but lack knowledge on how to select it.

ravenpl

Why You downloaded those sources.
You better give me output from those two commands
rpm -qa | grep ^kernel
uname -r

jl66

ASKER

Here they are:

[jeff@localhost ~]$ rpm -qa | grep ^kernel
kernel-2.6.27.5-117.fc10.i686
kernel-devel-2.6.27.19-170.2.35.fc10.i686
kerneloops-0.12-1.fc10.i386
kernel-firmware-2.6.27.5-117.fc10.noarch
kernel-headers-2.6.27.19-170.2.35.fc10.i386

[jeff@localhost ~]$ uname -r
2.6.27.5-117.fc10.i686

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ravenpl

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jl66

ASKER

After issuing that command and rebooting the server, re-issue the commands:

[jeff@localhost Documents]$ rpm -qa | grep ^kernel
kernel-2.6.27.5-117.fc10.i686
kernel-devel-2.6.27.19-170.2.35.fc10.i686
kerneloops-0.12-1.fc10.i386
kernel-devel-2.6.27.21-170.2.56.fc10.i686
kernel-headers-2.6.27.19-170.2.35.fc10.i386
kernel-2.6.27.21-170.2.56.fc10.i686
kernel-firmware-2.6.27.21-170.2.56.fc10.noarch

[jeff@localhost Documents]$ uname -r
2.6.27.21-170.2.56.fc10.i686

ravenpl

This is very strange, have You blocked the kernel updates in yum.conf?
Tyr installing: yum install kernel-2.6.27.19-170.2.35.fc10.i686

jl66

ASKER

[root@localhost ~]# yum install kernel-2.6.27.19-170.2.35.fc10.i686
Loaded plugins: refresh-packagekit
updates | 2.3 kB 00:00
fedora | 2.8 kB 00:00
Setting up Install Process
Parsing package install arguments
No package kernel-2.6.27.19-170.2.35.fc10.i686 available.
Nothing to do
----------------------
How do you think?

jl66

ASKER

I did not do anything on blocking the config. file. Can you tell me the commands I can check?

ravenpl

Sure, there's already newer one
Please download
ftp://download.fedora.redhat.com/pub/fedora/linux/updates/10/i386/kernel-2.6.27.21-170.2.56.fc10.i686.rpm
ftp://download.fedora.redhat.com/pub/fedora/linux/updates/10/i386/kernel-devel-2.6.27.21-170.2.56.fc10.i686.rpm
install them with
yum localinstall kernel-2.6.27.21-170.2.56.fc10.i686.rpm kernel-devel-2.6.27.21-170.2.56.fc10.i686.rpm
reboot
change the Makefile line back to
KVERSION = $(shell uname -r)

and build the module - it worked for me.

jl66

ASKER

[root@localhost Download]# yum localinstall kernel-2.6.27.21-170.2.56.fc10.i686.rpm kernel-devel-2.6.27.21-170.2.56.fc10.i686.rpm
Loaded plugins: refresh-packagekit
Setting up Local Package Process
Examining kernel-2.6.27.21-170.2.56.fc10.i686.rpm: kernel-2.6.27.21-170.2.56.fc10.i686
Marking kernel-2.6.27.21-170.2.56.fc10.i686.rpm as an update to kernel-2.6.27.5-117.fc10.i686
kernel-2.6.27.21-170.2.56.fc10.i686.rpm: does not update installed package.
Examining kernel-devel-2.6.27.21-170.2.56.fc10.i686.rpm: kernel-devel-2.6.27.21-170.2.56.fc10.i686
Marking kernel-devel-2.6.27.21-170.2.56.fc10.i686.rpm as an update to kernel-devel-2.6.27.19-170.2.35.fc10.i686
kernel-devel-2.6.27.21-170.2.56.fc10.i686.rpm: does not update installed package.
Resolving Dependencies
--> Running transaction check
---> Package kernel-devel.i686 0:2.6.27.21-170.2.56.fc10 set to be installed
---> Package kernel.i686 0:2.6.27.21-170.2.56.fc10 set to be installed
--> Finished Dependency Resolution

Dependencies Resolved

================================================================================
Package
Arch Version Repository Size
================================================================================
Installing:
kernel
i686 2.6.27.21-170.2.56.fc10 kernel-2.6.27.21-170.2.56.fc10.i686.rpm 50 M
kernel-devel
i686 2.6.27.21-170.2.56.fc10 kernel-devel-2.6.27.21-170.2.56.fc10.i686.rpm
18 M

Transaction Summary
================================================================================
Install 2 Package(s)
Update 0 Package(s)
Remove 0 Package(s)

Total download size: 68 M
Is this ok [y/N]: y
Downloading Packages:
Running rpm_check_debug
Running Transaction Test
Finished Transaction Test

Transaction Check Error:
package kernel-2.6.27.21-170.2.56.fc10.i686 is already installed
package kernel-devel-2.6.27.21-170.2.56.fc10.i686 is already installed

Error Summary
-------------

ravenpl

what about make now (changing the KVERSION line) ?