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CMSIS-RTOS: stack size to create a thread > 8000

steve kerich

Hi

I am using the new CMSIS-RTOS and seem to have a stack problem that I don't understand. In order to create even the simple of task (one that just polls a CAN interface) that will not cause a hard fault when created I cannot use a default thread stack size of 512 or even 4096. I have to declare a user stack size of 8000 bytes just to keep it from causing a hard fault when it is created.

Since the thread itself does not require hardly any memory at all, I assume it is the RTOS that requires the memory in order to start the thread. It does not make any sense to me why so much memory is needed.

I have had to declare user stacks for all of my threads in order to get them created without a hard fault. The system works fine if I do this.

Unfortunately I want to use 14 threads so I cannot continue to use this "work around" or avoid figuring out why the threads need such large stack sizes. This is because there apparently is a limit as to the number of user defined stacks.

Error: "too many threads with user-provided stack size"

My simple thread does not use any buffers and just a few local ints I cannot blame the threads themselves in that they are using too much memory. There is something more central that is causing this minimum of 8000 bytes for me to create a task.

I just cannot figure out what setting or whatever is causing the RTOS to want so much memory.

Does anyone have any ideas as to what I must have set up wrong in RTX_Conf_CM.c or what might be the cause of this per thread memory?

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    I am trying to learn RTX. I have some example code from the M0 book by Yui.
    Every thing I see in the examples is about TASK and not thread. I took a search
    for size. one thing I saw was the statement

    C:\Keil_v5\ARM\RV31\INC\RTL.h(220) :

    #define os_sys_init_user(tsk,prio,stk,size)

    Also

    C:\Keil_v5\ARM\RV31\INC\RTL.h(126) :
    #define os_sys_init_user(tsk,prio,stk,size)

    RTX Config C file
    // <o>Task stack size [bytes] <20-4096:8><#/4>
    // Set the stack size for tasks which is assigned by the system.
    //     Default: 200
    #ifndef OS_STKSIZE #define OS_STKSIZE 50
    #endif

    this one uses the default stack size defined in rtx.h

    #include <rtl.h>

    OS_TID os_tsk_create ( void (*task)(void), /* Task to create */ U8 priority ); /* Task priority (1-254) */

    http://www.keil.com/support/man/docs/rlarm/rlarm_os_tsk_create.htm

    I think the rtx.h is really supposed to be RTL.h.

    If you open RTL.h and look there is a config wizard and on my examples from the book
    the size of task stack size was 200 bytes.

    Gary

    \

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  • 0

    I am trying to learn RTX. I have some example code from the M0 book by Yui.
    Every thing I see in the examples is about TASK and not thread. I took a search
    for size. one thing I saw was the statement

    C:\Keil_v5\ARM\RV31\INC\RTL.h(220) :

    #define os_sys_init_user(tsk,prio,stk,size)

    Also

    C:\Keil_v5\ARM\RV31\INC\RTL.h(126) :
    #define os_sys_init_user(tsk,prio,stk,size)

    RTX Config C file
    // <o>Task stack size [bytes] <20-4096:8><#/4>
    // Set the stack size for tasks which is assigned by the system.
    //     Default: 200
    #ifndef OS_STKSIZE #define OS_STKSIZE 50
    #endif

    this one uses the default stack size defined in rtx.h

    #include <rtl.h>

    OS_TID os_tsk_create ( void (*task)(void), /* Task to create */ U8 priority ); /* Task priority (1-254) */

    http://www.keil.com/support/man/docs/rlarm/rlarm_os_tsk_create.htm

    I think the rtx.h is really supposed to be RTL.h.

    If you open RTL.h and look there is a config wizard and on my examples from the book
    the size of task stack size was 200 bytes.

    Gary

    \

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