Optimization issue in RISC-V BSP

Sat Jul 29 23:35:20 UTC 2017

2017-07-29 19:14 GMT+02:00 Joel Sherrill <joel at rtems.org>:

>
>
> On Jul 29, 2017 4:04 AM, "Denis Obrezkov" <denisobrezkov at gmail.com> wrote:
>
> 2017-07-29 3:45 GMT+02:00 Joel Sherrill <joel at rtems.org>:
>
>>
>>
>> On Jul 28, 2017 7:11 PM, "Denis Obrezkov" <denisobrezkov at gmail.com>
>> wrote:
>>
>> 2017-07-29 1:41 GMT+02:00 Joel Sherrill <joel at rtems.org>:
>>
>>>
>>>
>>> On Jul 28, 2017 6:39 PM, "Denis Obrezkov" <denisobrezkov at gmail.com>
>>> wrote:
>>>
>>> 2017-07-29 1:28 GMT+02:00 Joel Sherrill <joel at rtems.org>:
>>>
>>>>
>>>>
>>>> On Jul 28, 2017 6:14 PM, "Denis Obrezkov" <denisobrezkov at gmail.com>
>>>> wrote:
>>>>
>>>> 2017-07-29 0:57 GMT+02:00 Joel Sherrill <joel at rtems.org>:
>>>>
>>>>>
>>>>>
>>>>> On Jul 28, 2017 5:55 PM, "Denis Obrezkov" <denisobrezkov at gmail.com>
>>>>> wrote:
>>>>>
>>>>> 2017-07-28 22:36 GMT+02:00 Joel Sherrill <joel at rtems.org>:
>>>>>
>>>>>> Can you check the memory immediately after a download'?
>>>>>>
>>>>>> Then after the loop that copies initialized data into place?
>>>>>>
>>>>>> I suspect something off there. Could be a linker script issue or the
>>>>>> copy gone crazy.
>>>>>>
>>>>>> --joel
>>>>>>
>>>>>> On Fri, Jul 28, 2017 at 3:20 PM, Denis Obrezkov <
>>>>>> denisobrezkov at gmail.com> wrote:
>>>>>>
>>>>>>> 2017-07-28 22:16 GMT+02:00 Joel Sherrill <joel at rtems.org>:
>>>>>>>
>>>>>>>>
>>>>>>>>
>>>>>>>> On Fri, Jul 28, 2017 at 2:50 PM, Denis Obrezkov <
>>>>>>>> denisobrezkov at gmail.com> wrote:
>>>>>>>>
>>>>>>>>>
>>>>>>>>>>> I can see that during task initialization I have a call:
>>>>>>>>>>>  _Thread_Initialize_information (information=information at entry=0x80000ad4
>>>>>>>>>>> <_RTEMS_tasks_Information>, the_api=the_api at entry=OBJECTS_CLASSIC_API,
>>>>>>>>>>> the_class=the_class at entry=1, maximum=124,
>>>>>>>>>>>     is_string=is_string at entry=false,
>>>>>>>>>>> maximum_name_length=maximum_name_length at entry=4)
>>>>>>>>>>>
>>>>>>>>>>> And maximum is 124, but I have a configuration parameter:
>>>>>>>>>>> #define CONFIGURE_MAXIMUM_TASKS             4
>>>>>>>>>>>
>>>>>>>>>>
>>>>>>>>>> I can't imagine any standard RTEMS test configuring that many
>>>>>>>>>> tasks.
>>>>>>>>>> Is there a data corruption issue?
>>>>>>>>>>
>>>>>>>>>> 124 = 0x7c which doesn't ring any bells for me on odd memory
>>>>>>>>>> issues.
>>>>>>>>>>
>>>>>>>>>> What is the contents of "Configuration_RTEMS_API"?
>>>>>>>>>>
>>>>>>>>> Oh, I change my configuration options a bit, they are:
>>>>>>>>>   #define CONFIGURE_APPLICATION_NEEDS_CLOCK_DRIVER
>>>>>>>>>   #define CONFIGURE_APPLICATION_DISABLE_FILESYSTEM
>>>>>>>>>   #define CONFIGURE_DISABLE_NEWLIB_REENTRANCY
>>>>>>>>>   #define CONFIGURE_TERMIOS_DISABLED
>>>>>>>>>   #define CONFIGURE_LIBIO_MAXIMUM_FILE_DESCRIPTORS 0
>>>>>>>>>   #define CONFIGURE_MINIMUM_TASK_STACK_SIZE 512
>>>>>>>>>   #define CONFIGURE_MAXIMUM_PRIORITY 3
>>>>>>>>>   #define CONFIGURE_DISABLE_CLASSIC_API_NOTEPADS
>>>>>>>>>   #define CONFIGURE_IDLE_TASK_BODY Init
>>>>>>>>>   #define CONFIGURE_IDLE_TASK_INITIALIZES_APPLICATION
>>>>>>>>>   #define CONFIGURE_TASKS 4
>>>>>>>>>
>>>>>>>>>   #define CONFIGURE_MAXIMUM_TASKS             4
>>>>>>>>>
>>>>>>>>>   #define CONFIGURE_UNIFIED_WORK_AREAS
>>>>>>>>>
>>>>>>>>> Also it is the test from a lower ticker example.
>>>>>>>>> Configuration_RTEMS_API with -O0 option:
>>>>>>>>> {maximum_tasks = 5, maximum_timers = 0, maximum_semaphores = 7,
>>>>>>>>> maximum_message_queues = 0, maximum_partitions = 0, maximum_regions = 0,
>>>>>>>>> maximum_ports = 0, maximum_periods = 0,
>>>>>>>>>   maximum_barriers = 0, number_of_initialization_tasks = 0,
>>>>>>>>> User_initialization_tasks_table = 0x0}
>>>>>>>>>
>>>>>>>>> with -Os option:
>>>>>>>>> {maximum_tasks = 124, maximum_timers = 0, maximum_semaphores = 7,
>>>>>>>>> maximum_message_queues = 0, maximum_partitions = 0, maximum_regions = 0,
>>>>>>>>> maximum_ports = 0, maximum_periods = 0,
>>>>>>>>>   maximum_barriers = 0, number_of_initialization_tasks = 0,
>>>>>>>>> User_initialization_tasks_table = 0x0}
>>>>>>>>>
>>>>>>>>
>>>>>>>> Hmmm.. If you look at this structure in gdb without attaching to
>>>>>>>> the target, what
>>>>>>>> is maximum_tasks?
>>>>>>>>
>>>>>>>> --joel
>>>>>>>>
>>>>>>>>>
>>>>>>>>>
>>>>>>>>>
>>>>>>>>>>
>>>>>>>>>>>
>>>>>>>>>>> It seems that other tasks are LIBBLOCK tasks.
>>>>>>>>>>>
>>>>>>>>>>> Also, this is my Configuration during run:
>>>>>>>>>>> (gdb) p Configuration.stack_space_size
>>>>>>>>>>> $1 = 2648
>>>>>>>>>>> (gdb) p Configuration.work_space_size
>>>>>>>>>>> $2 = 4216
>>>>>>>>>>> (gdb) p Configuration.interrupt_stack_size
>>>>>>>>>>> $3 = 512
>>>>>>>>>>> (gdb) p Configuration.idle_task_stack_size
>>>>>>>>>>> $4 = 512
>>>>>>>>>>>
>>>>>>>>>>
>>>>>>>>>> That looks reasonable. Add CONFIGURE_MAXIMUM_PRIORITY and set it
>>>>>>>>>> to 4. That should
>>>>>>>>>> reduce the workspace.
>>>>>>>>>>
>>>>>>>>>>  long term, we might want to consider lowering it permanently
>>>>>>>>>> like one of the Coldfires
>>>>>>>>>> had to. Or change the default scheduler to the Simple one to save
>>>>>>>>>> memory.
>>>>>>>>>>
>>>>>>>>>>
>>>>>>>>> I haven't dealt with the Scheduler option yet.
>>>>>>>>>
>>>>>>>>>
>>>>>>>>>
>>>>>>>>> --
>>>>>>>>> Regards, Denis Obrezkov
>>>>>>>>>
>>>>>>>>
>>>>>>>> maximum_tasks = 4
>>>>>>> So, is it a linker file issue?
>>>>>>>
>>>>>>> This is it:
>>>>>>> https://github.com/embeddedden/rtems-riscv/blob/hifive1/c/sr
>>>>>>> c/lib/libbsp/riscv32/hifive1/startup/linkcmds
>>>>>>>
>>>>>>> --
>>>>>>> Regards, Denis Obrezkov
>>>>>>>
>>>>>>
>>>>>> After download:
>>>>> {maximum_tasks = 938162044, maximum_timers = 1270834941,
>>>>> maximum_semaphores = 2534801264 <(253)%20480-1264>,
>>>>> maximum_message_queues = 425684620, maximum_partitions = 1496738036,
>>>>>   maximum_regions = 3085560870 <(308)%20556-0870>, maximum_ports =
>>>>> 4269782132, maximum_periods = 2362012542 <(236)%20201-2542>,
>>>>> maximum_barriers = 1138223297, number_of_initialization_tasks = 4224313421,
>>>>>   User_initialization_tasks_table = 0x43bd1bd3}
>>>>>
>>>>> right after data copying:
>>>>> {maximum_tasks = 124, maximum_timers = 0, maximum_semaphores = 1,
>>>>> maximum_message_queues = 0, maximum_partitions = 0, maximum_regions = 0,
>>>>> maximum_ports = 0, maximum_periods = 0,
>>>>>   maximum_barriers = 0, number_of_initialization_tasks = 0,
>>>>> User_initialization_tasks_table = 0x0}
>>>>>
>>>>> But I found the mistake - I made it in .data initialization code
>>>>> (https://github.com/embeddedden/rtems-riscv/blob/hifive1/c/s
>>>>> rc/lib/libbsp/riscv32/hifive1/start/start.S#L116 - first byte in the
>>>>> loop was uninitialized)
>>>>>
>>>>>
>>>>> Awesome! Does that mean it is running?
>>>>>
>>>>>
>>>>>
>>>>> --
>>>>> Regards, Denis Obrezkov
>>>>>
>>>>>
>>>>> Yes, it is running now. Not far, but running.
>>>> Now I am having an exception during atexit( Clock_exit )
>>>>
>>>>
>>>> Does it get to bsp_cleanup and bsp_reset? Are you seeing the Terminate?
>>>>
>>>> I think those are the names. Basically some BSPs deliberately throw an
>>>> exception as the way to end.
>>>>
>>>>
>>>>
>>>>
>>>>
>>>> --
>>>> Regards, Denis Obrezkov
>>>>
>>>>
>>>> Unfortunately, I have an exception in the beginning during clock driver
>>> initialization around this line:
>>> 0x204053a0      80      in ../../../../../gcc-7.1.0/newli
>>> b/libc/stdlib/__atexit.c
>>>
>>>
>>> No obvious suggestions from me right now except to debug.
>>>
>>>
>>>
>>>
>>>
>>> --
>>> Regards, Denis Obrezkov
>>>
>>>
>>> Is it possible that newlib has a wrong linker file? That a variable
>> placed out of the rtems-linkcmd-defined bounds?
>>
>>
>> I don't think so. Look at the atexit source and see what it assume is
>> initialized
>>
>>
>>
>>
>> --
>> Regards, Denis Obrezkov
>>
>>
>> I found out that the error occurs in gcc-7.1.0/newlib/libc/stdlib/_
> _atexit.c:80:
> p = _GLOBAL_ATEXIT;
>
> p defined like:
> register struct _atexit *p;
>
> on the one hand the value of p is:
> (gdb) print p
> $56 = <optimized out>
>
> on the other hand:
> _GLOBAL_ATEXIT:
>
> #ifdef _REENT_GLOBAL_ATEXIT
> extern struct _atexit *_global_atexit; /* points to head of LIFO stack */
> # define _GLOBAL_ATEXIT _global_atexit
> #else
> # define _GLOBAL_ATEXIT (_GLOBAL_REENT->_atexit)
> #endif
>
> and _REENT_GLOBAL_ATEXIT should be defined due to
> (newlib/libc/include/sys):
> #if defined(__rtems__)
> #define __FILENAME_MAX__ 255
> #define _READ_WRITE_RETURN_TYPE _ssize_t
> #define __DYNAMIC_REENT__
> #define _REENT_GLOBAL_ATEXIT
> #endif
>
> but _global_atexit  located at random locations outside of my memory
> regions.
>
>
> Does it show up at a valid address when you look at the nm output?
>
> Does it behave differently when you drop optimization?
>
>
>
> --
> Regards, Denis Obrezkov
>
>
Oh, the pointer itself is located in a proper location, but the value it
stores is out of memory.
Anyway, it fails before it is able to utilize the wrong value.
It behaves the same way without optimization.

-- 
Regards, Denis Obrezkov
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