pthread_getattr_np does not work

Joel Sherrill joel at rtems.org
Mon Sep 25 16:29:54 UTC 2017


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.
>>>>
>>>>
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>>>> users mailing list
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>>>> http://lists.rtems.org/mailman/listinfo/users
>>>>
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