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Date: Mon, 23 Jun 2008 19:18:19 +0200
From: Philippe Gerum <rpm@xenomai.org>
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Subject: Re: [Xenomai-help] xenomai scheduler's ticks period
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To: Gilles Chanteperdrix <gilles.chanteperdrix@xenomai.org>, xenomai-help <xenomai@xenomai.org>

Gilles Chanteperdrix wrote:
> Philippe Gerum wrote:
>> Gilles Chanteperdrix wrote:
>>> Philippe Gerum wrote:
>>>> Matthieu wrote:
>>>>
>>>>> I have a segmentation fault error when I use modprobe xeno_vxworks
>>>>> tick_arg=0 (tick_arg=1000 works)
>>>>>
>>>> Any kernel log?
>>>>
>>> wind_sysclk_init uses its argument for a division.
>>>
>> --- ksrc/skins/vxworks/sysLib.c	(revision 3975)
>> +++ ksrc/skins/vxworks/sysLib.c	(working copy)
>> @@ -39,12 +39,12 @@
>>  int wind_sysclk_init(u_long period)
>>  {
>>  	extern u_long sync_time;
>> -	u_long init_rate = ONE_BILLION / period;
>> +	u_long init_rate = period ? ONE_BILLION / period : XN_APERIODIC_TICK;
>>  	int err;
>>
>>  	err = xntbase_alloc("vxworks", period, sync_time ? 0 : XNTBISO,
>>  			    &wind_tbase);
>> -	if (err)
>> +	if (err || period == 0)
>>  		return err;
>>
>>  	err = sysClkRateSet(init_rate);
> 
> Ok, but what about sysClkRateGet then ? It is needed for conversion
> between durations and ticks count. It will not work since sysClkRateSet
> was not called, and we can not call sysClkRateSet since it would start
> the timer.
> 
> 

We don't have to care about this. If people want to override the system timer,
then they should deal with the xntbase interface themselves. What is provided is
a mean to disable internal timing so that it does not conflict with the
user-provided stuff, nothing more.

-- 
Philippe.