[Xenomai-help] Kompiling an RT Kernel Module

[Xenomai-help] Kompiling an RT Kernel Module

[Axel Beierlein]

Hello,

Now a few hours i try to compile a simple file as an RT Kernel Module and  
i get errors over errors.
I have included the kernel sources and the xenomai sources in different  
ways. I get many "in file includes" and other errors.

What are the minimal requirements to compile such a native rt module?  
(include path, lib path ....)
I can´t use the output of xeno-config cause the rootfs on my target(ppc)  
is mounted over NFS from my development host(i386). I have a look at the  
makefile http://svn.gna.org/svn/xenomai/trunk/examples/common/Makefile but  
that solved not my probs. On the contrary it confuses me more and more  
cause i don´t understand why the Makro KSRC is defined as an pointer to  
the librarys and this Makro was also used to point to the Kernelheaders.

Is there anywhere an example working with support for cross-developement?

I´ve compiled the running kernel with all xenomai stuff inside (no  
modules) but with module load support on.

Axel

sorry for my terrible English ;-)

--------------------------------------------------------------------

The Example-Source of Kernel Module:

#include <native/task.h>

#define TASK_PRIO  99              /* Highest RT priority */
#define TASK_MODE  T_FPU|T_CPU(0)  /* Uses FPU, bound to CPU #0 */
#define TASK_STKSZ 4096            /* Stack size (in bytes) */

RT_TASK task_desc;

void task_body (void *cookie)
{
    for (;;) {
      /* ... "cookie" should be NULL ... */
      }
}

int init_module (void)
  {
	int err;

      /* ... */

     err = rt_task_create(&task_desc,
                           "MyTaskName",
                          TASK_STKSZ,
                          TASK_PRIO,
                          TASK_MODE);
      if (!err)
          rt_task_start(&task_desc,&task_body,NULL);

     /* ... */
  }

  void cleanup_module (void)
  {
      rt_task_delete(&task_desc);
  }

Re: [Xenomai-help] Kompiling an RT Kernel Module

[Jan Kiszka]

[-- Attachment #1: Type: text/plain, Size: 2110 bytes --]

Axel Beierlein wrote:
> Hello,
> 
> Now a few hours i try to compile a simple file as an RT Kernel Module and  
> i get errors over errors.
> I have included the kernel sources and the xenomai sources in different  
> ways. I get many "in file includes" and other errors.
> 
> What are the minimal requirements to compile such a native rt module?  
> (include path, lib path ....)

Just a standard kernel module makefile you'll find almost anywhere + a
Xenomai include path, ie.

EXTRA_CFLAGS := -I$(KSRC)/include/xenomai
(taken from your cited example)

> I can?t use the output of xeno-config cause the rootfs on my target(ppc)  
> is mounted over NFS from my development host(i386). I have a look at the  

You don't need to for a pure kernel module target. Just pick that
example and follow its instructions: Clear APPLICATIONS, put your module
into MODULES, then run make: "make KSRC=<kernel-src>". Must work, really.

> makefile http://svn.gna.org/svn/xenomai/trunk/examples/common/Makefile but  
> that solved not my probs. On the contrary it confuses me more and more  
> cause i don?t understand why the Makro KSRC is defined as an pointer to  
> the librarys and this Makro was also used to point to the Kernelheaders.

Try to find out what is behind /lib/modules/`uname -r`/build on your
box... :->
(Note that "$(shell <command>)" in a makefile means `<command>` in your
shell.)

> 
> Is there anywhere an example working with support for cross-developement?

If you use a cross-compiler, additionally pass its prefix like this:

make KSRC=... CROSS_COMPILE=...

If you compile for a different arch, add ARCH=... as well.

> 
> I?ve compiled the running kernel with all xenomai stuff inside (no  
> modules) but with module load support on.
> 
> Axel
> 
> sorry for my terrible English ;-)

It's very well readable! I guess you haven't seen truly terrible English
on mailing lists yet. ;)

Jan


PS: If someone feels like adding a few words / references about "how do
I compile a kernel module for Xenomai?" to the wiki, please go ahead!


[-- Attachment #2: OpenPGP digital signature --]
[-- Type: application/pgp-signature, Size: 250 bytes --]

Re: [Xenomai-help] Kompiling an RT Kernel Module

[Gilles Chanteperdrix]

On 6/29/07, Axel Beierlein <belatronix@domain.hid> wrote:
> I can´t use the output of xeno-config cause the rootfs on my target(ppc)
> is mounted over NFS from my development host(i386).

As said by others, xeno-config is not meant to be used for building
modules. However xeno-config is meant to be used in the
cross-compiling case: this is what its DESTDIR variable is for.

-- 
                                               Gilles Chanteperdrix