# IAR 5.41 getting to Hard Fault with low opt **URL:** \ **Category:** Kernel\ **Created:** [August 12, 2011, 4:21pm UTC](https://forums.freertos.org/t/iar-5-41-getting-to-hard-fault-with-low-opt/3385 "2011-08-12T16:21:50Z")\ **Posts on this page:** 6\ **Page:** 1
**Author:** ![system](https://d2v6vdsk2p900z.cloudfront.net/original/1X/7fc8fdb729c645aab5b20282bbe34e57cb407be6.jpeg) [@system](https://forums.freertos.org/u/system)\ **Post date:** [August 12, 2011, 4:21pm UTC](https://forums.freertos.org/t/iar-5-41-getting-to-hard-fault-with-low-opt/3385/1 "2011-08-12T16:21:50Z")
**[baranov](https://sourceforge.net/u/baranov/)** wrote on [Friday, August 12, 2011](https://sourceforge.net/p/freertos/discussion/382005/thread/8e599053/#bd7e): Hello. I am not really sure that the problem is FreeRtos related.  I have a project with one task consisting only of vTaskDelay(5000); When I compile the project with medium and high optimization options it works fine. When I switch to low it goes to Hard Fault Interrupt. When I single step, it runs to vPortStartFirstTask() and gets into: ``` vPortSVCHandler; ldr r3, =pxCurrentTCB ldr r1, [r3] ldr r0, [r1] ldmia r0!, {r4-r11} msr psp, r0 mov r0, #0 msr basepri, r0 orr r14, r14, #13 bx r14 ``` On exit from it my debugger shows: \*\*Usage fault: Attempt to use a coprocessor instruction! \*\* Of course I tried to vary stack and heap sizes but it did not clarify the situation. Could anybody give a clue, what did the optimization option change? ---
**Author:** ![rtel](https://d3iykfbgfh8zhg.cloudfront.net/user_avatar/forums.freertos.org/rtel/32/31_2.png) [@rtel](https://forums.freertos.org/u/rtel)\ **Post date:** [August 14, 2011, 10:35am UTC](https://forums.freertos.org/t/iar-5-41-getting-to-hard-fault-with-low-opt/3385/2 "2011-08-14T10:35:58Z")
**[rtel](https://sourceforge.net/u/rtel/)** wrote on [Sunday, August 14, 2011](https://sourceforge.net/p/freertos/discussion/382005/thread/8e599053/#07ee): I am guessing, and it is just a guess, that you are using a Cortex-M3 device. If so, then IAR V5.x is out of date.  Other than that, how is your C start up code written?  The symptom you describe can often happen when the start up is written completely in C, and is caused by a loop variable being stored on the stack with zero optimisation (and so getting wiped out by its own initialisation code) compared to the same variable being held in a register at higher optimisation (and so being safe from being wiped out by memory clearing and initialisation code). Regards. ---
**Author:** ![system](https://d2v6vdsk2p900z.cloudfront.net/original/1X/7fc8fdb729c645aab5b20282bbe34e57cb407be6.jpeg) [@system](https://forums.freertos.org/u/system)\ **Post date:** [August 15, 2011, 12:34pm UTC](https://forums.freertos.org/t/iar-5-41-getting-to-hard-fault-with-low-opt/3385/3 "2011-08-15T12:34:35Z")
**[baranov](https://sourceforge.net/u/baranov/)** wrote on [Monday, August 15, 2011](https://sourceforge.net/p/freertos/discussion/382005/thread/8e599053/#1508): Thank you very much!. Yes, it is STM32.  I will try IAR 6.10. ---
**Author:** ![system](https://d2v6vdsk2p900z.cloudfront.net/original/1X/7fc8fdb729c645aab5b20282bbe34e57cb407be6.jpeg) [@system](https://forums.freertos.org/u/system)\ **Post date:** [August 15, 2011, 2:04pm UTC](https://forums.freertos.org/t/iar-5-41-getting-to-hard-fault-with-low-opt/3385/4 "2011-08-15T14:04:36Z")
**[baranov](https://sourceforge.net/u/baranov/)** wrote on [Monday, August 15, 2011](https://sourceforge.net/p/freertos/discussion/382005/thread/8e599053/#0241): IAR 6.10 did not help. I saw that in **"medium**" option  vPortSVCHandler  enters assembler function shown above  with LR = 0xFFFFFFF9, which is correct and in “ **low** ” option LR has some other value. In my case it is e.g. 0x800D7FF. I guess, I simply have to use medium optimization. ---
**Author:** ![system](https://d2v6vdsk2p900z.cloudfront.net/original/1X/7fc8fdb729c645aab5b20282bbe34e57cb407be6.jpeg) [@system](https://forums.freertos.org/u/system)\ **Post date:** [August 15, 2011, 2:13pm UTC](https://forums.freertos.org/t/iar-5-41-getting-to-hard-fault-with-low-opt/3385/5 "2011-08-15T14:13:35Z")
**[davedoors](https://sourceforge.net/u/davedoors/)** wrote on [Monday, August 15, 2011](https://sourceforge.net/p/freertos/discussion/382005/thread/8e599053/#2216): Can you post the code that initializes the C run time environment. The bit that zeros out the memory, normally in a file called crt0 or cstart or startup, etc. ---
**Author:** ![system](https://d2v6vdsk2p900z.cloudfront.net/original/1X/7fc8fdb729c645aab5b20282bbe34e57cb407be6.jpeg) [@system](https://forums.freertos.org/u/system)\ **Post date:** [August 15, 2011, 2:52pm UTC](https://forums.freertos.org/t/iar-5-41-getting-to-hard-fault-with-low-opt/3385/6 "2011-08-15T14:52:47Z")
**[baranov](https://sourceforge.net/u/baranov/)** wrote on [Monday, August 15, 2011](https://sourceforge.net/p/freertos/discussion/382005/thread/8e599053/#8910): I think, I solved the problem. I had: ``` const intvec_elem __vector_table[] = { { . __ptr =__ sfe( "CSTACK" ) }, __iar_program_start, NMIException, HardFaultException, MemManageException, BusFaultException, UsageFaultException, 0, 0, 0, 0, // Reserved SVCHandler, DebugMonitor, 0, // Reserved PendSVC, SysTickHandler }; ``` and ``` void SVCHandler( void ) { #ifdef FREERTOS vPortSVCHandler(); #endif } ``` I replaced it by: ``` const intvec_elem __vector_table[] = { { . __ptr =__ sfe( "CSTACK" ) }, __iar_program_start, NMIException, HardFaultException, MemManageException, BusFaultException, UsageFaultException, 0, 0, 0, 0, // Reserved vPortSVCHandler, DebugMonitor, 0, // Reserved PendSVC, SysTickHandler }; ``` It eliminated call from SVCHandler and now it works with low optimization too. Any comments including scornful will be highly appreciated.