Re: [Xenomai-core] SOLO: Too limited priorities for vxWorks threads

[Philippe Gerum <rpm@xenomai.org>]

Philippe Gerum wrote:
> Niklaus Giger wrote:
>> Am Sonntag, 18. Mai 2008 schrieb Philippe Gerum:
>>> Niklaus Giger wrote:
>>>> Hi
>>>>
>>>> I just tried to get a sample test program to run under Xenomai-SOLO
>>>> and run into this panic message:
>>>> Xenomai/SOLO: current implementation restricts VxWorkspriority levels to range [-2..0]
>>>> looking at the code I found at taskLib.c
>>>>> 263     {
>>>>> 264             if (wind_prio < 0 || wind_prio > 255) /* In theory. */
>>>>> 265                     return S_taskLib_ILLEGAL_PRIORITY;
>>>>> 266
>>>>> 267             if (wind_prio >= threadobj_max_prio - 1) /* In practice. */
>>>>> 268                     panic("current implementation restricts VxWorks"
>>>>> 269                           "priority levels to range [%d..0]",
>>>>> 270                           threadobj_max_prio - 2);
>>>>> 271             return OK;
>>>> Therefore I seem to have only the option of priority 0 which is way too limited.
>>>>
>>> The SOLO version is purely Linux native, so you only get what the underlying
>>> kernel provides you, including in terms of available priority scales. Since RT
>>> threads are members of the SCHED_FIFO class, you get 99 priority levels, unless
>>> you patch the vanilla kernel to handle more. The way to solve this properly for
>>> SOLO is to write a patch against PREEMPT_RT that allows wider priority scales,
>>> and to get it merged upstream.
>> Sorry, but you did not get my point. I tried to call it with priority 50, which
>> should be in this range, which I verified with gdb
>> (gdb) info stack
>> #0  panic (fmt=0xb7eebb90 "current implementation restricts VxWorkspriority levels to range [%d..0]") at panic.c:45
>> #1  0xb7eea1ac in check_task_priority (wind_prio=50) at taskLib.c:268
>> #2  0xb7eea1d9 in __taskInit (task=0x9eda0e0, tcb=0x9eda10c, name=0xbfc43760 "BSysAsyncTimerMgrThread", prio=50, flags=0,
>>     entry=0x81281c4 <BSysOsWrapperThread_callback(int)>, stacksize=51200) at taskLib.c:284
>> <...>
>>
>> I am happy with the rang 0.99 and also will no run any latency tests, as
>> xenomai-SOLO is for me at the moment just a test bed to check for compiler
>> error etc, as at the moment I have no running powerpc kernel for my PPC440
>> target.
>>
> 
> Have a look at my next answer: the test fails because threadobj_max_prio is
> zero, which can't be the case after the emulator has properly initialized. You
> may have run into either of the following problems:
> 
> - since you seem to be using C++, don't create tasks in static constructors.
> They are run before solo_init() is called.
> 

Actually, don't do anything that involves the emulation services - except
calling kernelInit() - in static constructors.

> - make sure to call kernelInit() from the VxWorks emulation lib, just like the
> tests from the test suite do.
> 

i.e. kernelInit() calls solo_init(), which initializes the thread emulation
package, which sets threadobj_max_prio appropriately.

> 
>> Best regards
>>
> 
> 


-- 
Philippe.