Kernel development on Nios Linux 2.6 distribution

Hey come on!

Am I the only one wanting to develop kernel drivers with this package. I seriously doubt that...

Gimme some input here, please... http://forum.niosforum.com/work2/style_emoticons/<#EMO_DIR#>/laugh.gif

-Tervis

This message will describe building a hello_world driver for the kernel. The driver will be listed as a miscellaneous driver inside the kernel configuration tool.

(1) Create the code for the driver (hello_world.c):

#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 "Goodbye, cruel world\n");
}
module_init (hello_init);
module_exit (hello_exit);
MODULE_LICENSE("Dual BSD/GPL");

(2) Create the Makefile for the driver:

ifneq ($(KERNELRELEASE),)
#  This is the section of the Makefile that builds the module inside the kernel
obj-$(CONFIG_HELLO_WORLD) := hello_world.o
else
#  This section is for building the module outside of the source #  $(ECLIPSE_WORKSPACE) is assumed to be defined externally by the environment
#  please reference the articles on http://www.lwn.net regarding#  kernel module development for more information about this Makefile
KDIR := $(KERNEL_PLUGIN)/linux-2.6.x
KERNEL_PROJECT := eval_kit_0
BUILDDIR := $(ECLIPSE_WORKSPACE)/$(KERNEL_PROJECT)/build
PWD := $(shell pwd)
default:
    $(MAKE) -C $(KDIR) O=$(BUILDDIR) SUBDIRS=$(PWD) modules
endif

(3) Copy the two files into the source tree using the following few commands:

cd <wherever the above files live>
mkdir $(KERNEL_PLUGIN)/linux-2.6.x/misc/hello_world
cp * $(KERNEL_PLUGIN)/linux-2.6.x/drivers/misc/hello_world

(4) Update the Makefile and Kconfig file in the $(KERNEL_PLUGIN)/linux-2.6.x/drivers/misc directory...

##  Makefile for misc devices that really don't fit anywhere else.# 
obj- := misc.o   #  Dummy rule to force built-in.o to be made
obj-$(CONFIG_IBM_ASM)    += ibmasm/
#  add the following line
obj-$(CONFIG_HELLO_WORLD) += hello_world/

##  Misc strange devices# 
menu "Misc devices"
config IBM_ASM
    tristate "Device driver for IBM RSA service processor"
    depends on X86
    default n
    ---help---
   This option enables device driver support for in-band access to the
   IBM RSA (Condor) service processor in eServer xSeries systems.
   The ibmasm device driver allows user space application to access
   ASM (Advanced Systems Management) functions on the service
   processor. The driver is meant to be used in conjunction with
   a user space API.
   The ibmasm driver also enables the OS to use the UART on the
          service processor board as a regular serial port.
   
   If unsure, say N.
#  add the following few lines
config HELLO_WORLD
     tristate "Hello_world example"
     default n
endmenu

After saving all the modified files, you can now configure a kernel with the above driver. It is recommended that the driver be compiled into the kernel for testing purposes since that should help with the debugging effort.

The kernel option will appear in Device Drivers -> Miscellaneous -> Hello_world example.

Once you have configured, built, and uploaded your kernel, the kernel should start and display: "Hello, World!" while it is starting up.

Much of the above code was taken from LWN.net&#39;s Device driver series of articles.

Hope this helps...

Ken.

BTW, debugging is discussed within the reference manual I believe... I may post some additional instructions up here later on if people have trouble with debugging the kernel.

Is it possible to develop a kernel driver as an independant module ? This module will be dynamically linked in the kernel with insmod command.

I tried to develop such a module, like I used to do under "standard" Linux (Red Hat or Montavista), but I get several warnings on compiling "linux/module.h" and "linux/kernel.h". Is there other defines to add that __KERNEL__ and MODULE ? Should I use the standard C library for kernel development ?

<div class='quotetop'>QUOTE </div>

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Is it possible to develop a kernel driver as an independant module ? This module will be dynamically linked in the kernel with insmod command.[/b]

--- Quote End ---

Yep. You&#39;ll need to use insmod from busybox to load in the module. I&#39;ve done it a number of times using a very simple hello_world example driver.

<div class='quotetop'>QUOTE </div>

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Is there other defines to add that __KERNEL__ and MODULE ? Should I use the standard C library for kernel development ?[/b]

--- Quote End ---

That I&#39;m not sure of, my driver development skills aren&#39;t very strong. I would recommend the following two sites for more information.

linux device drivers, 2nd edition: online book (http://www.xml.com/ldd/chapter/book/)

lwn: porting device drivers to the 2.6 kernel (http://lwn.net/articles/driver-porting/)

I found that most of the information from both sources are quite applicable.

Hope this helps...

Previous answer is not enough to build a module independantly from Kernel. My goal is to have my source files on a separate directory (which is handled by a Software Configuration Manager, here ClearCase) with a Makefile to generate the .o module file.

I try to get back the compilation options from the .xxx.o.cmd file in kernel/build/drivers directory. I can now compile files and generate a module without any warning nor error. But this .o file is not recognized by insmod : it gives the following error message :

No module found in object

insmod: cannot insert "testModule_mod.o": Invalid module format (-1): Exec format error

Here is the Makefile (a little bit ... complicated !). With this Makefile, I tried to re-compile one Kernel driver, and I&#39;m very surprise to find an object with a different size (124kb instead of 126kb) : I surely made a mistake, but I can&#39;t see where (no errors, no warning... but a little small difference !).

all: testModule_mod.o
testModule_mod.o: testModule.o
    nios2-elf-ld  -mnios2elf  -r -o testModule_mod.o testModule.o
testModule.o: testModule.c Makefile
    nios2-elf-gcc -nostdinc -Wp,-MD,.testModule.o.d -iwithprefix include -D__KERNEL__ -Iinclude -Iinclude2 -I/cygdrive/c/altera/kits/nios2/bin/eclipse/plugins/com.microtronix.nios2linux.kernel_0.1.5/linux-2.6.x/include -I/cygdrive/c/altera/kits/nios2/bin/eclipse/plugins/com.microtronix.nios2linux.kernel_0.1.5/linux-2.6.x/ -I$(LIBMYKERNEL) -I$(LIBKERNEL) -D__KERNEL__ -I/cygdrive/c/altera/kits/nios2/bin/eclipse/plugins/com.microtronix.nios2linux.kernel_0.1.5/linux-2.6.x/include -Iinclude -I/cygdrive/c/altera/kits/nios2/bin/eclipse/plugins/com.microtronix.nios2linux.kernel_0.1.5/linux-2.6.x/include2 -Iinclude2  -I/cygdrive/c/altera/kits/nios2/bin/eclipse/plugins/com.microtronix.nios2linux.kernel_0.1.5/linux-2.6.x/include -Wall -Wstrict-prototypes -Wno-trigraphs -fno-strict-aliasing -fno-common -DNO_MM -pipe -D__linux__ -D__ELF__ -DNO_TEXT_SECTIONS -fno-builtin -O2 -g -G 0 -DUTS_SYSNAME=\"uClinux\"  -I/cygdrive/c/altera/kits/nios2/bin/nios2-gnutools/H-i686-pc-cygwin/bin/../lib/gcc-lib/nios2-elf/3.3.3/include -O2 -fomit-frame-pointer  -DKBUILD_BASENAME=testModule  -DMODULE -c -o testModule.o testModule.c

That&#39;s an extremely complicated makefile... have you tried using the Makefile I provided in this thread? It does allow for building outside of the kernel tree. As a bonus, it also pulls in all the necessary rules for building the module properly from the original kernel source instead of requiring you to specify the rules manually.

Give it a try, and post any errors that you get when you try running "make". It worked like a charm when I did it.

In fact, here&#39;s the Makefile tailored to your situation:

CONFIG_TEST_MOD=m
ifneq ($(KERNELRELEASE),)
#  This is the section of the Makefile that builds the module inside the kernel
obj-$(CONFIG_TEST_MOD) := testModule_mod.o
else
#  This section is for building the module outside of the source#  $(ECLIPSE_WORKSPACE) is assumed to be defined externally by the environment
#  please reference the articles on http://www.lwn.net regarding#  kernel module development for more information about this Makefile
KDIR := $(KERNEL_PLUGIN)/linux-2.6.x
$(error You need to specify the kernel project that this module is being built for before this will work!)#  delete the above line after you have modified the variable below to its proper setting
KERNEL_PROJECT := your_kernel_project
BUILDDIR := $(ECLIPSE_WORKSPACE)/$(KERNEL_PROJECT)/build
PWD := $(shell pwd)
default:
$(MAKE) -C $(KDIR) O=$(BUILDDIR) SUBDIRS=$(PWD) modules
endif

I&#39;m sorry, but I still have a lot of errors with your Makefile. I think the basic environment information is missing...

Here are the error messages : (invoked directly from NIOS II-IDE, Build project option)

<div class='quotetop'>QUOTE </div>

--- Quote Start ---

make -k default

make -C /cygdrive/c/altera/kits/nios2/bin/eclipse/plugins/com.microtronix.nios2linux.kernel_0.1.5/linux-2.6.x O=/cygdrive/c/altera/kits/nios2/bin/eclipse/workspace/Kernel_DemoBoard_LAN/build SUBDIRS=/cygdrive/c/altera/kits/nios2/bin/eclipse/workspace/testModule modules

make[1]: Entering directory `/cygdrive/c/altera/kits/nios2/bin/eclipse/plugins/com.microtronix.nios2linux.kernel_0.1.5/linux-2.6.x&#39;

/cygdrive/c/altera/kits/nios2/bin/eclipse/plugins/com.microtronix.nios2linux.kernel_0.1.5/linux-2.6.x/Makefile:421: /cygdrive/c/altera/kits/nios2/bin/eclipse/plugins/com.microtronix.nios2linux.kernel_0.1.5/linux-2.6.x/arch/i386/Makefile: No such file or directory

gcc: not found

make[2]: *** No rule to make target `/cygdrive/c/altera/kits/nios2/bin/eclipse/plugins/com.microtronix.nios2linux.kernel_0.1.5/linux-2.6.x/arch/i386/Makefile&#39;.

make[2]: Failed to remake makefile `/cygdrive/c/altera/kits/nios2/bin/eclipse/plugins/com.microtronix.nios2linux.kernel_0.1.5/linux-2.6.x/arch/i386/Makefile&#39;.

gcc: not found

Using /cygdrive/c/altera/kits/nios2/bin/eclipse/plugins/com.microtronix.nios2linux.kernel_0.1.5/linux-2.6.x as source for kernel

gcc: not found

*** Warning: Overriding SUBDIRS on the command line can cause

*** inconsistencies

gcc: not found

HOSTCC scripts/basic/fixdep

gcc: not found

make[3]: *** [scripts/basic/fixdep] Error 127

make[3]: Target `__build&#39; not remade because of errors.

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

make[2]: Target `modules&#39; not remade because of errors.

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

make[1]: Leaving directory `/cygdrive/c/altera/kits/nios2/bin/eclipse/plugins/com.microtronix.nios2linux.kernel_0.1.5/linux-2.6.x&#39;

make: *** [default] Error 2[/b]

--- Quote End ---

It appears that architecture information is missing, as Cross-compiler. So I tried to add &#39;ARCH=nios2nommu CROSS_COMPILE=nios2-elf-&#39; in $(MAKE) command. Result is better, but there is still problems :

<div class='quotetop'>QUOTE </div>

--- Quote Start ---

make -k default

make -C /cygdrive/c/altera/kits/nios2/bin/eclipse/plugins/com.microtronix.nios2linux.kernel_0.1.5/linux-2.6.x ARCH=nios2nommu CROSS_COMPILE=nios2-elf- O=/cygdrive/c/altera/kits/nios2/bin/eclipse/workspace/Kernel_DemoBoard_LAN/build SUBDIRS=/cygdrive/c/altera/kits/nios2/bin/eclipse/workspace/testModule modules

make[1]: Entering directory `/cygdrive/c/altera/kits/nios2/bin/eclipse/plugins/com.microtronix.nios2linux.kernel_0.1.5/linux-2.6.x&#39;

Using /cygdrive/c/altera/kits/nios2/bin/eclipse/plugins/com.microtronix.nios2linux.kernel_0.1.5/linux-2.6.x as source for kernel

*** Warning: Overriding SUBDIRS on the command line can cause

*** inconsistencies

HOSTCC scripts/basic/fixdep

gcc: not found

make[3]: *** [scripts/basic/fixdep] Error 127

make[3]: Target `__build&#39; not remade because of errors.

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

make[2]: Target `modules&#39; not remade because of errors.

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

make: *** [default] Error 2

make[1]: Leaving directory `/cygdrive/c/altera/kits/nios2/bin/eclipse/plugins/com.microtronix.nios2linux.kernel_0.1.5/linux-2.6.x&#39;[/b]

--- Quote End ---

Don&#39;t you have such errors ?

Ah... I see. I forgot to mention that I meant for you to use the Makefile from Nios II SDK shell. There isn&#39;t an appropriate project type within the Nios II IDE for module/driver development yet.

The Nios II SDK shell will contain all the correct environment variables that you need. It will also contain a correct PATH setting.

Give it another shot through the Nios II SDK Shell and let me know how it goes...

OK, it&#39;s perfect ! I&#39;m sorry for so many exchanges for a so easy conclusion !

Hope it may help other guys !

Hi,

To continue on this same subject, I just dowloaded the new release 1.3 and I try to compile my driver, as a module.

It doesn&#39;t compile any more : the error is "cannot find .config file".

It seems to look for this file in the "plugins" kernel directory instead of my kernel directory.

Is there something to change in the Makefile ?

CONFIG_TEST_MOD=m
ifneq ($(KERNELRELEASE),)
#  This is the section of the Makefile that builds the module inside the kernel
obj-$(CONFIG_TEST_MOD) := JGXEOE.o
else
#  This section is for building the module outside of the source#  $(ECLIPSE_WORKSPACE) is assumed to be defined externally by the environment
#  please reference the articles on http://www.lwn.net regarding#  kernel module development for more information about this Makefile
KERNEL_PLUGIN := /cygdrive/c/altera/kits/nios2/bin/eclipse/plugins/com.microtronix.nios2linux.kernel_0.1.5
ECLIPSE_WORKSPACE := /cygdrive/c/altera/kits/nios2/bin/eclipse/workspace
KDIR := $(KERNEL_PLUGIN)/linux-2.6.x
KERNEL_PROJECT := Kernel_MUX
BUILDDIR := $(ECLIPSE_WORKSPACE)/$(KERNEL_PROJECT)/build
PWD := $(shell pwd)
default:
    $(MAKE) -C $(KDIR) O=$(BUILDDIR) SUBDIRS=$(PWD) modules
endif