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

[Philippe Gerum <rpm@xenomai.org>]

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.

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


> Best regards
> 


-- 
Philippe.