| View previous topic :: View next topic |
| Author |
Message |
IRQsRFun
Apprentice
Joined: 02 May 2003
Posts: 195
Location: Somewhere between .3 and .7 Vdd
|
 Posted: Mon Nov 05, 2007 12:34 am Post subject: Looking for a device driver template (solved) |
 |
|
I am currently looking at an O'Rielly book Linux Device Drivers (for linux version 2.4). I now realize there may be some fundamental differences between kernel 2.4 and 2.6 (duh).
When I try to build the first example, I get a large number of warnings and errors.
Here is a what the example is trying to do (text changed):
| Code: |
int init_module(void) { printk("<1>Init Module\n"); return 0; }
void cleanup_module(void) { printk("<1>Cleanup Module\n"); }
|
I know this is insanely simple, but I have to start somewhere.
I have looked around in the linux sources, but I did not find anything I felt confortable using witout some guidance.
Any help would be appreciated.
Last edited by IRQsRFun on Sat Nov 10, 2007 2:18 pm; edited 1 time in total |
|
| Back to top |
|
 |
entox
n00b
Joined: 19 Jun 2005
Posts: 36
|
| Posted: Wed Nov 07, 2007 6:37 pm Post subject: |
|
|
Hi
also had some trouble with this.
Here is a simple HelloWorld-Module:
| Code: |
#include <linux/init.h>
#include <linux/module.h>
#include <linux/kernel.h>
static int hello_init(void) {
printk(KERN_ALERT "Hello World \n");
return 0;
}
static void hello_exit(void) {
printk(KERN_ALERT "Finishing ... \n");
}
module_init(hello_init);
module_exit(hello_exit);
MODULE_LICENSE("GPL");
MODULE_AUTHOR("Entox");
|
Afaik in 2.6 you have to register the init / exit -Function explicit using module_init, module_exit.
Entox |
|
| Back to top |
|
|
IRQsRFun
Apprentice
Joined: 02 May 2003
Posts: 195
Location: Somewhere between .3 and .7 Vdd
|
| Posted: Thu Nov 08, 2007 12:00 am Post subject: Thank you but.... |
|
|
Thank you for your reply.
So far, I have had to add:
before
| Code: |
#include <linux/module.h>
|
I am still working on other compile errors. Is there something you are using to setup gcc before compiling?
I am currently doing this to build:
| Code: |
gcc -c -I/usr/src/linux/include hello.c &> temp
|
Any help would be appreciated. |
|
| Back to top |
|
|
IRQsRFun
Apprentice
Joined: 02 May 2003
Posts: 195
Location: Somewhere between .3 and .7 Vdd
|
| Posted: Thu Nov 08, 2007 3:02 am Post subject: |
|
|
Update:
Got your original to compile by adding
#include <linux/autoconf.h>
on the top line.
I also had to take from a makefile and get:
| Code: |
KERNELDIR = /usr/src/linux
include $(KERNELDIR)/.config
CFLAGS = -D__KERNEL__ -DMODULE -I$(KERNELDIR)/include \
-O -Wall
ifdef CONFIG_SMP
CFLAGS += -D__SMP__ -DSMP
endif
all: hello.o
|
When I execute
dmesg reports:
| Quote: |
No module found in object
|
insmod reports:
| Quote: |
insmod: error inserting 'hello.o': -1 Invalid module format
|
Any help would be appreciated. |
|
| Back to top |
|
|
dev_zero
n00b
Joined: 01 Nov 2007
Posts: 28
Location: Somewhere in the kernel source
|
| Posted: Thu Nov 08, 2007 4:38 am Post subject: |
|
|
This is how the makefile should look like:
| Code: | obj-m += hello-1.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 |
Btw there is a guide about kernel module programming over at tldp. http://tldp.org/LDP/lkmpg/2.6/html/index.html
_________________
Dell Latitude D630 DSDT |
|
| Back to top |
|
|
IRQsRFun
Apprentice
Joined: 02 May 2003
Posts: 195
Location: Somewhere between .3 and .7 Vdd
|
| Posted: Fri Nov 09, 2007 2:11 am Post subject: |
|
|
Thank you dev_zero for the response and the link.
However, I am still having trouble.
I am using the makefile and the hello world program in the above link. (same makefile as above) If you are new to makefiles and reading this, please undestand that make uses tabs, not spaces for indentation.
Here is my error:
| Quote: |
prompt # make
make -C /lib/modules/2.6.24-rc2/build M=/root/Desktop/hello_world modules
make: *** /lib/modules/2.6.24-rc2/build: No such file or directory. Stop.
make: *** [all] Error 2
|
| Quote: |
prompt # ls /lib/modules/2.6.24-rc2
modules.alias modules.ieee1394map modules.ofmap modules.symbols
modules.ccwmap modules.inputmap modules.pcimap modules.usbmap
modules.dep modules.isapnpmap modules.seriomap video
|
As shown, there is no file named build in lib/modules/2.6.24-rc2.
Any help would be appreciated |
|
| Back to top |
|
|
IRQsRFun
Apprentice
Joined: 02 May 2003
Posts: 195
Location: Somewhere between .3 and .7 Vdd
|
| Posted: Sat Nov 10, 2007 2:17 pm Post subject: |
|
|
Success!!
Somewhere between 2.6.18-gentoo-r2 and 2.6.18-gentoo-r3 the symbolic link build was not included in /lib/modules/XXXX. Therefore, I had to change my makefile to:
| Code: |
obj-m = hello.o
# all:
# make -C /lib/modules/$(shell uname -r)/build M=$(PWD) modules
all:
make -C /usr/src/linux M=$(PWD) modules
# clean:
# make -C /lib/modules/$(shell uname -r)/build M=$(PWD) clean
clean:
make -C /usr/src/linux M=$(PWD) clean
|
thank you to all who have tried to help me with this hello world build. |
|
| Back to top |
|
|
|
Kernel & Hardware
