pthread_getattr_np does not work

Tue Sep 26 15:16:44 UTC 2017

Yes. Then pthread_create a thread to use that stack, let it run,
and make sure pthread_getattr_np reports things correctly.

On Tue, Sep 26, 2017 at 6:52 AM, xuelin.tian at qkmtech.com <
xuelin.tian at qkmtech.com> wrote:

> You mean, I allocate an array of some size in another thread, and set the
> pointer of this array as the stack address using pthread_attr_setstackaddr?
>
>
> ------------------------------
> Best wishes,
> xuelin.tian at qkmtech.com
>
>
> *From:* Joel Sherrill <joel at rtems.org>
> *Date:* 2017-09-26 00:29
> *To:* xuelin.tian at qkmtech.com
> *CC:* users at rtems.org; Sebastian Huber
> <sebastian.huber at embedded-brains.de>
> *Subject:* Re: Re: pthread_getattr_np does not work
> I would suggest adding a test of another thread with a user provided stack
> space that is properly aligned (e.g. array of double of minimum stack size
> divided by sizeof(double)). This would give you known address range and
> size for that thread.
>
> For the case of RTEMS allocating the stack, the pointer returned to you
> will vary based on the BSP and will essentially be random to the
> application.
> If the application allocates it, then it knows the starting address.
>
> You should be able to add that to the existing test without much trouble.
>
> --joel
>
>
> On Sun, Sep 24, 2017 at 9:45 PM, xuelin.tian at qkmtech.com <
> xuelin.tian at qkmtech.com> wrote:
>
>> OK, I will try to do this.
>>
>> ------------------------------
>> Best wishes,
>> xuelin.tian at qkmtech.com
>>
>>
>> *From:* Joel Sherrill <joel at rtems.org>
>> *Date:* 2017-09-24 21:32
>> *To:* xuelin.tian <xuelin.tian at qkmtech.com>
>> *CC:* rtems-users at rtems.org <users at rtems.org>; Sebastian Huber
>> <sebastian.huber at embedded-brains.de>
>> *Subject:* Re: Re: pthread_getattr_np does not work
>> No. But you are welcome to submit patches so the behavior matches Linux.
>>
>> On Sep 24, 2017 1:09 AM, "xuelin.tian" <xuelin.tian at qkmtech.com> wrote:
>>
>>> So, is there a substitute function for this in RTEMS, without modifying
>>> the source code?
>>>
>>>
>>> ------------------ Original ------------------
>>> *From: * "Joel Sherrill"<joel at rtems.org>;
>>> *Date: * Sun, Sep 24, 2017 00:15 AM
>>> *To: * "xuelin.tian"<xuelin.tian at qkmtech.com>;
>>> *Cc: * "Sebastian Huber"<sebastian.huber at embedded-brains.de>; "
>>> users at rtems.org"<users at rtems.org>;
>>> *Subject: * Re: Re: pthread_getattr_np does not work
>>>
>>>
>>>
>>> On Fri, Sep 22, 2017 at 9:26 PM, xuelin.tian <xuelin.tian at qkmtech.com>
>>> wrote:
>>>
>>>> Thanks so much for your test.
>>>>
>>>
>>> No problem. Just trying to help.
>>>
>>>
>>>> The parts of this structure I care about most are the stackaddr and
>>>> stacksize (and guardsize maybe), where stackaddr always returns 0. The
>>>> value of stacksize is either 8192 or 0, based on the fact that this
>>>> attribute structure is retrieved from POSIX_Init or other pthreads in my
>>>> system (maybe I use pthread_create in a wrong way...).
>>>>
>>>
>>> Without looking at the code, 8192 is almost certainly the port specific
>>> default
>>> stack size since it is normally a value like that. A stack size request
>>> of anything
>>> less than the recommended minimum will always get you an allocation of
>>> the
>>> minimum. So 0 or 8192 might simply indicate whether the structure is
>>> explicitly
>>> initialized via pthread_attr_init() or filled in explicitly by the
>>> application with
>>> the minimum stack size constant.
>>>
>>>
>>>>
>>>> So, from the result you post, the stackaddr is 0 too, which means this
>>>> element is not supported in rtems, or there is something wrong with this
>>>> function?
>>>>
>>>
>>> This means the user application didn't specify the stack area in RTEMS.
>>> Since
>>> this method is "NP", there is no standard specifying the behavior.
>>>
>>> This method doesn't exist on FreeBSD and appears to only exist in Linux
>>> and
>>> RTEMS. If there is consensus that it should behave the same on Linux and
>>> RTEMS, then there should be a ticket filed with (hopefully) patches.
>>> <hint>
>>>
>>> It isn't a complicated method and all if should take is filling in the
>>> attribute
>>> structure with different fields in the TCB. I think it primarily parrots
>>> back
>>> the attribute structure passed to pthread_create().
>>>
>>> Also writing the man page for the RTEMS POSIX manual would be
>>> appreciated.
>>>
>>> Nothing like wandering into something that is even beyond unspecified in
>>> POSIX to a method that is explicitly non-portable for fun. :)
>>>
>>> --joel
>>>
>>> --joel
>>>
>>>>
>>>>
>>>> ------------------ Original ------------------
>>>> *From: * "Joel Sherrill"<joel at rtems.org>;
>>>> *Date: * Fri, Sep 22, 2017 10:15 PM
>>>> *To: * "xuelin.tian at qkmtech.com"<xuelin.tian at qkmtech.com>;
>>>> *Cc: * "Sebastian Huber"<sebastian.huber at embedded-brains.de>; "
>>>> users at rtems.org"<users at rtems.org>;
>>>> *Subject: * Re: Re: pthread_getattr_np does not work
>>>>
>>>> The test does verify the values. I don't see a specific case of
>>>> creating a thread
>>>> with a non-standard stack value and verifying that value in the task
>>>> but the
>>>> test creates a thread which retrieves its values and verifies many
>>>> (most, all?)
>>>> of them:
>>>>
>>>> (gdb)
>>>> Thread - pthread_getattr_np - Verify value
>>>> 46        sc = pthread_getattr_np( Thread_id, &attr );
>>>> (gdb)
>>>> 47        rtems_test_assert( sc == 0 );
>>>> (gdb)
>>>> 52        puts( "Thread - pthread_setschedparam: Setting highest
>>>> priority SCHED_FIFO" );
>>>> (gdb) p attr
>>>> $1 = {is_initialized = 1, stackaddr = 0x0, stacksize = 8192,
>>>>   contentionscope = 0, inheritsched = 2, schedpolicy = 2, schedparam = {
>>>>     sched_priority = 3, sched_ss_low_priority = 285216961,
>>>>     sched_ss_repl_period = {tv_sec = 0, tv_nsec = 16},
>>>>     sched_ss_init_budget = {tv_sec = 0, tv_nsec = 1}, sched_ss_max_repl
>>>> = 0},
>>>>   guardsize = 0, cputime_clock_allowed = 1, detachstate = 1,
>>>>   affinitysetsize = 0, affinityset = 0x0, affinitysetpreallocated = {
>>>>     __bits = {0}}}
>>>>
>>>> Clearly the attribute structure returned is not all zero.
>>>>
>>>> I am not sure what you are seeing but it doesn't match what I see in
>>>> this test on the erc32.
>>>>
>>>> --joel
>>>>
>>>> On Fri, Sep 22, 2017 at 4:04 AM, xuelin.tian at qkmtech.com <
>>>> xuelin.tian at qkmtech.com> wrote:
>>>>
>>>>> OK, no problem, thanks anyway.
>>>>>
>>>>> ------------------------------
>>>>> Best wishes,
>>>>> xuelin.tian at qkmtech.com
>>>>>
>>>>>
>>>>> *From:* Sebastian Huber <sebastian.huber at embedded-brains.de>
>>>>> *Date:* 2017-09-22 16:58
>>>>> *To:* xuelin.tian at qkmtech.com; users at rtems.org
>>>>> *Subject:* Re: pthread_getattr_np does not work
>>>>> On 22/09/17 10:55, xuelin.tian at qkmtech.com wrote:
>>>>>
>>>>> > OK, I will try to do some fix on this function. And if Sherrill and
>>>>> > you have time, please take some time on this. Thanks a lot.
>>>>>
>>>>> No, sorry. I have no time to fix this.
>>>>>
>>>>> --
>>>>> Sebastian Huber, embedded brains GmbH
>>>>>
>>>>> Address : Dornierstr. 4
>>>>> <https://maps.google.com/?q=Dornierstr.+4&entry=gmail&source=g>,
>>>>> D-82178 Puchheim, Germany
>>>>> Phone   : +49 89 189 47 41-16
>>>>> Fax     : +49 89 189 47 41-09
>>>>> E-Mail  : sebastian.huber at embedded-brains.de
>>>>> PGP     : Public key available on request.
>>>>>
>>>>> Diese Nachricht ist keine geschäftliche Mitteilung im Sinne des EHUG.
>>>>>
>>>>>
>>>>> _______________________________________________
>>>>> users mailing list
>>>>> users at rtems.org
>>>>> http://lists.rtems.org/mailman/listinfo/users
>>>>>
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