Antwort: Re: help reqd rgd example preempt pls(with denx core)

Wolfgang Grandegger wolfgang.grandegger at
Wed Oct 6 15:41:28 CEST 2004

On 10/06/2004 09:41 AM deepa.vijayaraghavan at wrote:
> Hi Wolfgang,
>    Here, are a few details.
> ELDK Ver 3.0
> Linux : Linuxppc_2_4_devel
> Patch: patch-denx-linuxppc_2_4_devel-LABEL_2004_04_30_1320
> RTAI: rtai-24.1.12
> The example I am referring to, is the one in
> rtai-24.1.1/examples/preempt directory.
> The module gets built when I build the RTAI.
> The ebony board boots up fine. I 'insmod' rtai.o, rtai_fifos.o,
> rtai_sched_up.o. I get all outputs, as it should be, as stated in
> README.install on the denx ftp server.
> Then I insmod $MYPATH/rtai-24.1.1/examples/preempt/ex_preempt.o
> I run check.
> I get no output. I tried adding some rt_printk statements within the
> while loop in the tasks, nothing gets printed. But rmmod returns with no
> error.
> Once I changed the second parameter of the rt_task_make_periodic()
> function to 0, I started getting output, a few times, based on the
> number of times the tasks get scheduled before the completion of the
> init_module() function.
> I do not know why the tasks don't run continuously.
> In rmmod, I checked the return value of rt_task_delete(). No errors. So,
> the tasks do exist!
> I use One shot timer. If I use periodic timer, I get no output at all in
> any case.
> I do not understand what you mean by 'can we have a look at the test
> module'. Do you want me to attach the built module, that I have here?

No, I thought you are using a hand-made module and not the preempt
example as-is. Does the latency calibration test work properly and what
does the output look like. Unfortunately I do not have an Ebony board
and therefore I cannot try to reproduce your problem.


> 	*wolfgang.grandegger at*
> Gesendet von: rtai-admin at
> 05.10.2004 22:04
>         An:        deepa.vijayaraghavan at
>         Kopie:        rtai at
>         Thema:        Re: help reqd rgd example preempt pls(with denx core)
> On 10/01/2004 09:39 AM deepa.vijayaraghavan at wrote:
>> hi all,
>> there were a few mistakes, as the earlier mail was typed in a hurry..
>> sorry abt that.
>> I am referring to the example preempt, that demonstrates how a higher
>> priority task and a lower priority task work together. My application is
>> also sort of similar, hence clarity on this example will help me a great
>> deal.
>> I am using IBM ppc 440 based ebony board.
>> In the functions rt_task_make_periodic(), if the second parameter is
>> left as it is(now + tick_period), I get no output. Infact when I check
>> if the task gets scheduled at all, by using rt_printk statements, I get
>> no output.
>> But if I set the delay to 0(or some small number), I get output so long
>> as the init_module() runs. I get output based on the number of times the
>> tasks get scheduled before the init_module() function is completed. I
>> use 'insmod' for the loading the module.
>> When I do rmmod, the tasks are terminated without errors.
>> The same is the case with the 'Frank' example too.
>> I use the 'One shot' timer. With 'periodic' timer, i see no output
>> whatsoever.
>> Any help is highly appreciated.
> Can you please provide more information on the problems and errors. What
> version of RTAI are you using? Can we have a look to a test module
> demostrating the problem?
> Wolfgang.
> _______________________________________________
> RTAI mailing list
> RTAI at

More information about the Rtai mailing list