# Stack destroyed after return from long vTaskDelay

**URL:** <https://forums.freertos.org/t/stack-destroyed-after-return-from-long-vtaskdelay/24787>\
**Category:** Kernel\
**Created:** [December 19, 2025, 10:05am UTC](https://forums.freertos.org/t/stack-destroyed-after-return-from-long-vtaskdelay/24787 "2025-12-19T10:05:35Z")\
**Posts on this page:** 20\
**Page:** 1

<div class="post-metadata">

**Author:** ![rasty1](https://d3iykfbgfh8zhg.cloudfront.net/user_avatar/forums.freertos.org/rasty1/32/5886_2.png) [@rasty1](https://forums.freertos.org/u/rasty1)\
**Post date:** [December 19, 2025, 10:05am UTC](https://forums.freertos.org/t/stack-destroyed-after-return-from-long-vtaskdelay/24787/1 "2025-12-19T10:05:35Z")

</div>

Hi  
I’m struggling with some problem. after return from vTaskDelay task stack is destroyed. I wrapped vTaskDelay and check sp (cortex R5). What I see is that SP is not(!) between between pxStack and pxTopOfStack as I would expect. Task defined as _static task_.  
Need some fresh idea?

 ![image](https://d2v6vdsk2p900z.cloudfront.net/original/2X/2/2c81531df1266b0c653cf78175b9df7b70a6af18.png)  
Thanks

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<div class="post-metadata">

**Author:** ![aggarg](https://d3iykfbgfh8zhg.cloudfront.net/user_avatar/forums.freertos.org/aggarg/32/4245_2.png) [@aggarg](https://forums.freertos.org/u/aggarg)\
**Post date:** [December 19, 2025, 11:25am UTC](https://forums.freertos.org/t/stack-destroyed-after-return-from-long-vtaskdelay/24787/2 "2025-12-19T11:25:26Z")

</div>

`pxTopOfStack` is updated at the time of context switch. So this may not be a problem. Can you check if SP is between `pxStack` and `(pxStack + stack_size_in_bytes)`? Are you facing any problem?

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<div class="post-metadata">

**Author:** ![rasty1](https://d3iykfbgfh8zhg.cloudfront.net/user_avatar/forums.freertos.org/rasty1/32/5886_2.png) [@rasty1](https://forums.freertos.org/u/rasty1)\
**Post date:** [December 19, 2025, 2:26pm UTC](https://forums.freertos.org/t/stack-destroyed-after-return-from-long-vtaskdelay/24787/3 "2025-12-19T14:26:05Z")

</div>

Hi  
Good idea! as far as I can see stack size/depth is not stored in tcb. I added it to tcb.  
I my goal it to figure out where stack corruption takes place before and during sleep. I have to do it in vTaskDelay wrapper, because any modification to application code changes whole picture.  
I’ll keep you posted.  
Rasty

---

<div class="post-metadata">

**Author:** ![RAc](https://d3iykfbgfh8zhg.cloudfront.net/user_avatar/forums.freertos.org/rac/32/1389_2.png) [@RAc](https://forums.freertos.org/u/RAc)\
**Post date:** [December 19, 2025, 8:34pm UTC](https://forums.freertos.org/t/stack-destroyed-after-return-from-long-vtaskdelay/24787/4 "2025-12-19T20:34:49Z")

</div>

be aware, though, that the corruption of your sp may be a symptom of something that happens at a completly different place in the system (for example, something overtrampling memory that ends right before a sytem data structure whose corruption causes what you see as a side effect). If you can pinpoint a faulty write to a specific memory address as the culprit, your best strategy is a hardware breakpoint on that location.

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<div class="post-metadata">

**Author:** ![aggarg](https://d3iykfbgfh8zhg.cloudfront.net/user_avatar/forums.freertos.org/aggarg/32/4245_2.png) [@aggarg](https://forums.freertos.org/u/aggarg)\
**Post date:** [December 22, 2025, 5:28am UTC](https://forums.freertos.org/t/stack-destroyed-after-return-from-long-vtaskdelay/24787/5 "2025-12-22T05:28:07Z")

</div>

As I said before, this may not be the case of SP corruption. Would you please describe the problem you are trying to solve? As @RAc mentioned, data breakpoints are very useful when trying to catch memory corruptions.

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<div class="post-metadata">

**Author:** ![rasty1](https://d3iykfbgfh8zhg.cloudfront.net/user_avatar/forums.freertos.org/rasty1/32/5886_2.png) [@rasty1](https://forums.freertos.org/u/rasty1)\
**Post date:** [December 22, 2025, 6:44am UTC](https://forums.freertos.org/t/stack-destroyed-after-return-from-long-vtaskdelay/24787/6 "2025-12-22T06:44:48Z")

</div>

Hi  
thanks for suggestions.  
it is bit more complicated.  
due to optimization , vtaskdelay inserted between preparing of argument (constant) in register and call itself  
ld r10, constant\_path – argument for fopen  
vtaskdelay(const)  
fopen(constant\_path\_in\_r10)

sometimes r10 gets garbage in fopen.

hardware watchpoint does not help becase only register is corrupted , not memory.  
i use trace.

i’ll keep you posted and add disassemble in the next reply.  
thanks  
rasty

---

<div class="post-metadata">

**Author:** ![rasty1](https://d3iykfbgfh8zhg.cloudfront.net/user_avatar/forums.freertos.org/rasty1/32/5886_2.png) [@rasty1](https://forums.freertos.org/u/rasty1)\
**Post date:** [December 22, 2025, 8:47am UTC](https://forums.freertos.org/t/stack-destroyed-after-return-from-long-vtaskdelay/24787/7 "2025-12-22T08:47:37Z")

</div>

OK.  
I managed to put a break point and catch corrupted data (with fopen wrapper and simple if). What I see that after return from vTaskDelay register R7 is does not carry expected data. It is not direct memory corruption , because R9 is loaded from constant, before call to vTaskDelay.  
I rule out instruction memory corruption - I checked opcodes, they match disassembly.

 ![crash_fopen](https://d2v6vdsk2p900z.cloudfront.net/original/2X/9/9a1579f0cdcb7363b178f4dc4ba2bf18ecb226d2.jpeg)  
I cannot upload full instrcution trace because of account limitation.  
Any fresh idea would be approciated.

Thanks  
Rasty

97390,End of trace, Entered debug state when halting debug-mode is enabled,UNKNOWN,??:0  
97389,0x8028763C,0x8A000007,97388,\_\_wrap\_fopen,newlib\_locks.c:332  
97388,0x80287638,0xE3730219,97387,\_\_wrap\_fopen,newlib\_locks.c:332  
97387,0x80287634,0xE51B3010,97386,\_\_wrap\_fopen,newlib\_locks.c:332  
97386,0x80287630,0xE50B1014,97385,\_\_wrap\_fopen,newlib\_locks.c:331  
97385,0x8028762C,0xE50B0010,97384,\_\_wrap\_fopen,newlib\_locks.c:331  
97384,0x80287628,0xE24DD010,97383,\_\_wrap\_fopen,newlib\_locks.c:331  
97383,0x80287624,0xE28DB004,97382,\_\_wrap\_fopen,newlib\_locks.c:331  
97382,0x80287620,0xE92D4800,97381,\_\_wrap\_fopen,newlib\_locks.c:331  
97381,0x80213850,0xEB01CF72,97380,cStatistics::SaveStatisticsTask(void\*),Statistics.cpp:276  
97380,0x8021384C,0xE1A00007,97379,cStatistics::SaveStatisticsTask(void\*),Statistics.cpp:276  
97379,0x80213848,0xE1A0100A,97378,cStatistics::SaveStatisticsTask(void\*),Statistics.cpp:276  
97378,0x70107AFE,0x0000BD30,97377,vTaskDelay,tasks.c:2479  
97377,0x70107AFC,0x0000B003,97376,vTaskDelay,tasks.c:2479  
97376,0x70100214,0xF8BD0A00,97375,HwiP\_svc\_handler,portASM.S:149  
97375,0x70100210,0xE8BD5FFF,97374,HwiP\_svc\_handler,portASM.S:149  
97374,0x7010020C,0xF57FF01F,97373,HwiP\_svc\_handler,portASM.S:149  
97373,0x70100208,0x1EE10A10,97372,HwiP\_svc\_handler,portASM.S:149  
97372,0x70100204,0x1CBD0B20,97371,HwiP\_svc\_handler,portASM.S:149  
97371,0x70100200,0x149D0004,97370,HwiP\_svc\_handler,portASM.S:149  
97370,0x701001FC,0xE3510000,97369,HwiP\_svc\_handler,portASM.S:149  
97369,0x701001F8,0xE5801000,97368,HwiP\_svc\_handler,portASM.S:149  
97368,0x701001F4,0xE49D1004,97367,HwiP\_svc\_handler,portASM.S:149  
97367,0x701001F0,0xE59F0150,97366,HwiP\_svc\_handler,portASM.S:149  
97366,0x701001EC,0xE591D000,97365,HwiP\_svc\_handler,portASM.S:149  
97365,0x701001E8,0xE5901000,97364,HwiP\_svc\_handler,portASM.S:149  
97364,0x701001E4,0xE59F0158,97363,HwiP\_svc\_handler,portASM.S:149  
97363,0x70106250,0xE8BD8FF0,97362,vTaskSwitchContext,tasks.c:5140  
97362,0x7010624E,0x0000B005,97361,vTaskSwitchContext,tasks.c:5140  
97361,0x7010624A,0xF8CA3000,97360,vTaskSwitchContext,tasks.c:5126  
97360,0x70106246,0xF8D33088,97359,vTaskSwitchContext,tasks.c:5126  
97359,0x70106242,0xF8D93000,97358,vTaskSwitchContext,tasks.c:5126  
97358,0x7010623E,0xF8D93000,97357,vTaskSwitchContext,tasks.c:5121  
97357,0x7010623A,0xF8CB4000,97356,vTaskSwitchContext,tasks.c:5115  
97356,0x70106236,0xF8C93000,97355,vTaskSwitchContext,tasks.c:5115  
97355,0x70106234,0x000068DB,97354,vTaskSwitchContext,tasks.c:5115  
97354,0x70106232,0x00006053,97353,vTaskSwitchContext,tasks.c:5115  
97353,0x70106230,0x000068D3,97352,vTaskSwitchContext,tasks.c:5115  
97352,0x7010622E,0x0000BF04,97351,vTaskSwitchContext,tasks.c:5115  
97351,0x7010622C,0x000042B3,97350,vTaskSwitchContext,tasks.c:5115  
97350,0x7010622A,0x00006053,97349,vTaskSwitchContext,tasks.c:5115  
97349,0x70106228,0x0000685B,97348,vTaskSwitchContext,tasks.c:5115  
97348,0x70106226,0x00006853,97347,vTaskSwitchContext,tasks.c:5115  
97347,0x70106224,0x00003608,97346,vTaskSwitchContext,tasks.c:5115  
97346,0x70106222,0x00004616,97345,vTaskSwitchContext,tasks.c:5115  
97345,0x7010621E,0xEB060283,97344,vTaskSwitchContext,tasks.c:5115  
97344,0x7010621C,0x00004423,97343,vTaskSwitchContext,tasks.c:5115  
97343,0x70106218,0xF8DD900C,97342,vTaskSwitchContext,tasks.c:5115  
97342,0x70106216,0x000000A3,97341,vTaskSwitchContext,tasks.c:5115  
97341,0x70106214,0x0000464E,97340,vTaskSwitchContext,tasks.c:5115  
97340,0x70106212,0x0000D0F2,97339,vTaskSwitchContext,tasks.c:5115  
97339,0x70106210,0x00002B00,97338,vTaskSwitchContext,tasks.c:5115  
97338,0x7010620C,0xF8553D14,97337,vTaskSwitchContext,tasks.c:5115  
97337,0x802F068A,0x00004770,97336,\_DebugP\_assert,DebugP\_log.c:92  
97336,0x802F0688,0x0000B100,97335,\_DebugP\_assert,DebugP\_log.c:92  
97335,0x7015991C,0xE51FF004,97334,\_\_\_DebugP\_assert\_from\_arm,:?  
97334,0x70106208,0xF053EB88,97333,vTaskSwitchContext,tasks.c:5115  
97333,0x70106206,0x00003C01,97332,vTaskSwitchContext,tasks.c:5115  
97332,0x70106204,0x00009600,97331,vTaskSwitchContext,tasks.c:5115  
97331,0x70106202,0x00004639,97330,vTaskSwitchContext,tasks.c:5115  
97330,0x70106200,0x00004642,97329,vTaskSwitchContext,tasks.c:5115  
97329,0x701061FE,0x00004620,97328,vTaskSwitchContext,tasks.c:5115  
97328,0x701061FA,0xF24133FB,97327,vTaskSwitchContext,tasks.c:5115  
97327,0x70106212,0x0000D0F2,97326,vTaskSwitchContext,tasks.c:5115  
97326,0x70106210,0x00002B00,97325,vTaskSwitchContext,tasks.c:5115  
97325,0x7010620C,0xF8553D14,97324,vTaskSwitchContext,tasks.c:5115  
97324,0x802F068A,0x00004770,97323,\_DebugP\_assert,DebugP\_log.c:92  
97323,0x802F0688,0x0000B100,97322,\_DebugP\_assert,DebugP\_log.c:92  
97322,0x7015991C,0xE51FF004,97321,\_\_\_DebugP\_assert\_from\_arm,:?  
97321,0x70106208,0xF053EB88,97320,vTaskSwitchContext,tasks.c:5115  
97320,0x70106206,0x00003C01,97319,vTaskSwitchContext,tasks.c:5115  
97319,0x70106204,0x00009600,97318,vTaskSwitchContext,tasks.c:5115  
97318,0x70106202,0x00004639,97317,vTaskSwitchContext,tasks.c:5115  
97317,0x70106200,0x00004642,97316,vTaskSwitchContext,tasks.c:5115  
97316,0x701061FE,0x00004620,97315,vTaskSwitchContext,tasks.c:5115  
97315,0x701061FA,0xF24133FB,97314,vTaskSwitchContext,tasks.c:5115  
97314,0x70106212,0x0000D0F2,97313,vTaskSwitchContext,tasks.c:5115  
97313,0x70106210,0x00002B00,97312,vTaskSwitchContext,tasks.c:5115  
97312,0x7010620C,0xF8553D14,97311,vTaskSwitchContext,tasks.c:5115  
97311,0x802F068A,0x00004770,97310,\_DebugP\_assert,DebugP\_log.c:92  
97310,0x802F0688,0x0000B100,97309,\_DebugP\_assert,DebugP\_log.c:92  
97309,0x7015991C,0xE51FF004,97308,\_\_\_DebugP\_assert\_from\_arm,:?  
97308,0x70106208,0xF053EB88,97307,vTaskSwitchContext,tasks.c:5115  
97307,0x70106206,0x00003C01,97306,vTaskSwitchContext,tasks.c:5115  
97306,0x70106204,0x00009600,97305,vTaskSwitchContext,tasks.c:5115  
97305,0x70106202,0x00004639,97304,vTaskSwitchContext,tasks.c:5115  
97304,0x70106200,0x00004642,97303,vTaskSwitchContext,tasks.c:5115  
97303,0x701061FE,0x00004620,97302,vTaskSwitchContext,tasks.c:5115  
97302,0x701061FA,0xF24133FB,97301,vTaskSwitchContext,tasks.c:5115  
97301,0x70106212,0x0000D0F2,97300,vTaskSwitchContext,tasks.c:5115  
97300,0x70106210,0x00002B00,97299,vTaskSwitchContext,tasks.c:5115  
97299,0x7010620C,0xF8553D14,97298,vTaskSwitchContext,tasks.c:5115  
97298,0x802F068A,0x00004770,97297,\_DebugP\_assert,DebugP\_log.c:92  
97297,0x802F0688,0x0000B100,97296,\_DebugP\_assert,DebugP\_log.c:92  
97296,0x7015991C,0xE51FF004,97295,\_\_\_DebugP\_assert\_from\_arm,:?  
97295,0x70106208,0xF053EB88,97294,vTaskSwitchContext,tasks.c:5115  
97294,0x70106206,0x00003C01,97293,vTaskSwitchContext,tasks.c:5115  
97293,0x70106204,0x00009600,97292,vTaskSwitchContext,tasks.c:5115  
97292,0x70106202,0x00004639,97291,vTaskSwitchContext,tasks.c:5115  
97291,0x70106200,0x00004642,97290,vTaskSwitchContext,tasks.c:5115  
97290,0x701061FE,0x00004620,97289,vTaskSwitchContext,tasks.c:5115  
97289,0x701061FA,0xF24133FB,97288,vTaskSwitchContext,tasks.c:5115  
97288,0x70106212,0x0000D0F2,97287,vTaskSwitchContext,tasks.c:5115  
97287,0x70106210,0x00002B00,97286,vTaskSwitchContext,tasks.c:5115  
97286,0x7010620C,0xF8553D14,97285,vTaskSwitchContext,tasks.c:5115  
97285,0x802F068A,0x00004770,97284,\_DebugP\_assert,DebugP\_log.c:92  
97284,0x802F0688,0x0000B100,97283,\_DebugP\_assert,DebugP\_log.c:92  
97283,0x7015991C,0xE51FF004,97282,\_\_\_DebugP\_assert\_from\_arm,:?  
97282,0x70106208,0xF053EB88,97281,vTaskSwitchContext,tasks.c:5115  
97281,0x70106206,0x00003C01,97280,vTaskSwitchContext,tasks.c:5115  
97280,0x70106204,0x00009600,97279,vTaskSwitchContext,tasks.c:5115  
97279,0x70106202,0x00004639,97278,vTaskSwitchContext,tasks.c:5115  
97278,0x70106200,0x00004642,97277,vTaskSwitchContext,tasks.c:5115  
97277,0x701061FE,0x00004620,97276,vTaskSwitchContext,tasks.c:5115  
97276,0x701061FA,0xF24133FB,97275,vTaskSwitchContext,tasks.c:5115  
97275,0x70106212,0x0000D0F2,97274,vTaskSwitchContext,tasks.c:5115  
97274,0x70106210,0x00002B00,97273,vTaskSwitchContext,tasks.c:5115  
97273,0x7010620C,0xF8553D14,97272,vTaskSwitchContext,tasks.c:5115  
97272,0x802F068A,0x00004770,97271,\_DebugP\_assert,DebugP\_log.c:92  
97271,0x802F0688,0x0000B100,97270,\_DebugP\_assert,DebugP\_log.c:92  
97270,0x7015991C,0xE51FF004,97269,\_\_\_DebugP\_assert\_from\_arm,:?  
97269,0x70106208,0xF053EB88,97268,vTaskSwitchContext,tasks.c:5115  
97268,0x70106206,0x00003C01,97267,vTaskSwitchContext,tasks.c:5115  
97267,0x70106204,0x00009600,97266,vTaskSwitchContext,tasks.c:5115  
97266,0x70106202,0x00004639,97265,vTaskSwitchContext,tasks.c:5115  
97265,0x70106200,0x00004642,97264,vTaskSwitchContext,tasks.c:5115  
97264,0x701061FE,0x00004620,97263,vTaskSwitchContext,tasks.c:5115  
97263,0x701061FA,0xF24133FB,97262,vTaskSwitchContext,tasks.c:5115  
97262,0x701061F8,0x00004690,97261,vTaskSwitchContext,tasks.c:5115  
97261,0x701061F6,0x00004646,97260,vTaskSwitchContext,tasks.c:5115  
97260,0x701061F2,0xF2C70710,97259,vTaskSwitchContext,tasks.c:5115  
97259,0x701061F0,0x000046B1,97258,vTaskSwitchContext,tasks.c:5115  
97258,0x701061EC,0xF2C70210,97257,vTaskSwitchContext,tasks.c:5115  
97257,0x701061E8,0xF8CD900C,97256,vTaskSwitchContext,tasks.c:5115  
97256,0x701061E4,0xF2C70810,97255,vTaskSwitchContext,tasks.c:5115  
97255,0x701061E0,0xF64537E0,97254,vTaskSwitchContext,tasks.c:5115  
97254,0x701061DC,0xF6484278,97253,vTaskSwitchContext,tasks.c:5115  
97253,0x701061D8,0xF2461828,97252,vTaskSwitchContext,tasks.c:5115  
97252,0x701061D6,0x0000BB0A,97251,vTaskSwitchContext,tasks.c:5115  
97251,0x701061D2,0xF8562022,97250,vTaskSwitchContext,tasks.c:5115  
97250,0x701061CE,0xEB060582,97249,vTaskSwitchContext,tasks.c:5115  
97249,0x701061CC,0x000000A3,97248,vTaskSwitchContext,tasks.c:5115  
97248,0x701061C8,0xF8C10088,97247,vTaskSwitchContext,tasks.c:5106  
97247,0x701061C4,0xEB040284,97246,vTaskSwitchContext,tasks.c:5115  
97246,0x701061C0,0xF8DA0000,97245,vTaskSwitchContext,tasks.c:5106  
97245,0x701061BC,0xF8DB4000,97244,vTaskSwitchContext,tasks.c:5115  
97244,0x701061B8,0xF2C70A10,97243,vTaskSwitchContext,tasks.c:5106  
97243,0x701061B4,0xF2C70610,97242,vTaskSwitchContext,tasks.c:5115  
97242,0x701061B0,0xF6425AA0,97241,vTaskSwitchContext,tasks.c:5106  
97241,0x701061AC,0xF2C70B10,97240,vTaskSwitchContext,tasks.c:5115  
97240,0x701061A8,0xF8D91000,97239,vTaskSwitchContext,tasks.c:5106  
97239,0x701061A4,0xF64256B0,97238,vTaskSwitchContext,tasks.c:5115  
97238,0x701061A0,0xF2430B48,97237,vTaskSwitchContext,tasks.c:5115  
97237,0x7010619E,0x0000D959,97236,vTaskSwitchContext,tasks.c:5101  
97236,0x7010619C,0x0000429A,97235,vTaskSwitchContext,tasks.c:5101  
97235,0x7010619A,0x00006B1B,97234,vTaskSwitchContext,tasks.c:5101  
97234,0x70106198,0x0000680A,97233,vTaskSwitchContext,tasks.c:5101  
97233,0x70106196,0x00006010,97232,vTaskSwitchContext,tasks.c:5096  
97232,0x70106192,0xF8D93000,97231,vTaskSwitchContext,tasks.c:5101  
97231,0x7010618E,0xF8D91000,97230,vTaskSwitchContext,tasks.c:5101  
97230,0x7010618C,0x00006818,97229,vTaskSwitchContext,tasks.c:5096  
97229,0x7010618A,0x000067C1,97228,vTaskSwitchContext,tasks.c:5089  
97228,0x70106188,0x00001949,97227,vTaskSwitchContext,tasks.c:5089  
97227,0x70106186,0x0000BF84,97226,vTaskSwitchContext,tasks.c:5089  
97226,0x70106184,0x00001B09,97225,vTaskSwitchContext,tasks.c:5089  
97225,0x70106182,0x00006FC1,97224,vTaskSwitchContext,tasks.c:5089  
97224,0x7010617E,0xF8D90000,97223,vTaskSwitchContext,tasks.c:5089  
97223,0x7010617C,0x0000681D,97222,vTaskSwitchContext,tasks.c:5089  
97222,0x7010617A,0x0000BF81,97221,vTaskSwitchContext,tasks.c:5089  
97221,0x70106178,0x000042A1,97220,vTaskSwitchContext,tasks.c:5087  
97220,0x70106176,0x00006819,97219,vTaskSwitchContext,tasks.c:5087  
97219,0x70106174,0x00006018,97218,vTaskSwitchContext,tasks.c:5077  
97218,0x70106172,0x00006814,97217,vTaskSwitchContext,tasks.c:5087  
97217,0x7010616E,0xF2C70910,97216,vTaskSwitchContext,tasks.c:5089  
97216,0x7010616A,0xF2C70210,97215,vTaskSwitchContext,tasks.c:5087  
97215,0x70106166,0xF64259A4,97214,vTaskSwitchContext,tasks.c:5089  
97214,0x70106162,0xF2C70310,97213,vTaskSwitchContext,tasks.c:5077  
97213,0x7010615E,0xF2430230,97212,vTaskSwitchContext,tasks.c:5087  
97212,0x7010615A,0xF2430334,97211,vTaskSwitchContext,tasks.c:5077  
97211,0x7010902E,0x0000BD08,97210,uiPortGetRunTimeCounterValue,port.c:357  
97210,0x802F0C4E,0x00001830,97209,ClockP\_getTimeUsec,ClockP\_freertos.c:298  
97209,0x802F0C4A,0xFB027705,97208,ClockP\_getTimeUsec,ClockP\_freertos.c:292  
97208,0x802F0C46,0xFBB3F0F0,97207,ClockP\_getTimeUsec,ClockP\_freertos.c:294  
97207,0x802F0C42,0xFBA26704,97206,ClockP\_getTimeUsec,ClockP\_freertos.c:292  
97206,0x802F0C3E,0xFB02F303,97205,ClockP\_getTimeUsec,ClockP\_freertos.c:294  
97205,0x802F0C3C,0x000043C0,97204,ClockP\_getTimeUsec,ClockP\_freertos.c:294  
97204,0x802F0C3A,0x00001A1B,97203,ClockP\_getTimeUsec,ClockP\_freertos.c:294  
97203,0x802F0C38,0x000068B2,97202,ClockP\_getTimeUsec,ClockP\_freertos.c:292  
97202,0x802F0C36,0x00006B30,97201,ClockP\_getTimeUsec,ClockP\_freertos.c:294  
97201,0x802F0C32,0xF1450500,97200,ClockP\_getTimeUsec,ClockP\_freertos.c:288  
97200,0x802F0C30,0x00003401,97199,ClockP\_getTimeUsec,ClockP\_freertos.c:288  
97199,0x802F0C2E,0x0000B117,97198,ClockP\_getTimeUsec,ClockP\_freertos.c:286  
97198,0x802F0C2C,0x0000D1E4,97197,ClockP\_getTimeUsec,ClockP\_freertos.c:283 (discriminator 1)  
97197,0x802F0C2A,0x00002900,97196,ClockP\_getTimeUsec,ClockP\_freertos.c:283 (discriminator 1)  
97196,0x802F0C26,0xF0410101,97195,ClockP\_getTimeUsec,ClockP\_freertos.c:283 (discriminator 1)  
97195,0x802F0C24,0x0000BF88,97194,ClockP\_getTimeUsec,ClockP\_freertos.c:283 (discriminator 1)  
97194,0x802F0C22,0x00004582,97193,ClockP\_getTimeUsec,ClockP\_freertos.c:283 (discriminator 1)  
97193,0x802F0C20,0x00004603,97192,ClockP\_getTimeUsec,ClockP\_freertos.c:281 (discriminator 1)  
97192,0x802F0C1E,0x00002100,97191,ClockP\_getTimeUsec,ClockP\_freertos.c:283 (discriminator 1)  
97191,0x802F0C1C,0x00002101,97190,ClockP\_getTimeUsec,ClockP\_freertos.c:283 (discriminator 1)  
97190,0x802F0C1A,0x00004544,97189,ClockP\_getTimeUsec,ClockP\_freertos.c:283 (discriminator 1)  
97189,0x802F0C18,0x0000BF0A,97188,ClockP\_getTimeUsec,ClockP\_freertos.c:283 (discriminator 1)  
97188,0x802F0C16,0x0000454D,97187,ClockP\_getTimeUsec,ClockP\_freertos.c:283 (discriminator 1)  
97187,0x802F0C12,0xE9D64500,97186,ClockP\_getTimeUsec,ClockP\_freertos.c:282 (discriminator 1)  
97186,0x802F1E3A,0x00004770,97185,TimerP\_getCount,TimerP.c:171  
97185,0x802F1E38,0x00006BC0,97184,TimerP\_getCount,TimerP.c:170  
97184,0x802F0CA4,0xF001B8C8,97183,ClockP\_getTimerCount,ClockP\_freertos\_r5.c:43  
97183,0x802F0C0E,0xF000F849,97182,ClockP\_getTimeUsec,ClockP\_freertos.c:281 (discriminator 1)  
97182,0x802F0C0C,0x00006AF0,97181,ClockP\_getTimeUsec,ClockP\_freertos.c:281 (discriminator 1)  
97181,0x802F0C0A,0x00004607,97180,ClockP\_getTimeUsec,ClockP\_freertos.c:278 (discriminator 1)  
97180,0x802F1E56,0x00004770,97179,TimerP\_isOverflowed,TimerP.c:212  
97179,0x802F1E52,0xF3C00040,97178,TimerP\_isOverflowed,TimerP.c:212  
97178,0x802F1E50,0x00006A40,97177,TimerP\_isOverflowed,TimerP.c:209  
97177,0x802F0C06,0xF001F923,97176,ClockP\_getTimeUsec,ClockP\_freertos.c:278 (discriminator 1)  
97176,0x802F0C04,0x00006AF0,97175,ClockP\_getTimeUsec,ClockP\_freertos.c:278 (discriminator 1)  
97175,0x802F0C02,0x00004682,97174,ClockP\_getTimeUsec,ClockP\_freertos.c:271 (discriminator 1)  
97174,0x802F0C00,0x000046A9,97173,ClockP\_getTimeUsec,ClockP\_freertos.c:271 (discriminator 1)  
97173,0x802F1E3A,0x00004770,97172,TimerP\_getCount,TimerP.c:171  
97172,0x802F1E38,0x00006BC0,97171,TimerP\_getCount,TimerP.c:170  
97171,0x802F0CA4,0xF001B8C8,97170,ClockP\_getTimerCount,ClockP\_freertos\_r5.c:43  
97170,0x802F0BFC,0xF000F852,97169,ClockP\_getTimeUsec,ClockP\_freertos.c:271 (discriminator 1)  
97169,0x802F0BFA,0x000046A0,97168,ClockP\_getTimeUsec,ClockP\_freertos.c:271 (discriminator 1)  
97168,0x802F0BF8,0x00006AF0,97167,ClockP\_getTimeUsec,ClockP\_freertos.c:271 (discriminator 1)  
97167,0x802F0BF4,0xE9D64500,97166,ClockP\_getTimeUsec,ClockP\_freertos.c:262  
97166,0x802F0BF0,0xF2C8060E,97165,ClockP\_getTimeUsec,ClockP\_freertos.c:262  
97165,0x802F0BEC,0xF64F5600,97164,ClockP\_getTimeUsec,ClockP\_freertos.c:262  
97164,0x802F0BE8,0xE92D47F0,97163,ClockP\_getTimeUsec,ClockP\_freertos.c:262  
97163,0x70159710,0xE51FF004,97162,\_\_ClockP\_getTimeUsec\_veneer,:?  
97162,0x7010614E,0xE92D4FF0,97161,vTaskSwitchContext,tasks.c:5057  
97161,0x7010614A,0xF2C70310,97160,vTaskSwitchContext,tasks.c:5069  
97160,0x70106148,0x00002200,97159,vTaskSwitchContext,tasks.c:5069  
97159,0x70106144,0xF24303C8,97158,vTaskSwitchContext,tasks.c:5069  
97158,0x70106722,0xF7FFBD0F,97157,vTaskSwitchContext,tasks.c:5140  
97157,0x70106720,0x00004770,97156,vTaskSwitchContext,tasks.c:5140  
97156,0x7010671E,0x0000601A,97155,vTaskSwitchContext,tasks.c:5065  
97155,0x7010671A,0xF2C70310,97154,vTaskSwitchContext,tasks.c:5065  
97154,0x70106718,0x00002201,97153,vTaskSwitchContext,tasks.c:5065  
97153,0x70106714,0xF24303C8,97152,vTaskSwitchContext,tasks.c:5065  
97152,0x70106712,0x0000B133,97151,vTaskSwitchContext,tasks.c:5061  
97151,0x70106710,0x0000681B,97150,vTaskSwitchContext,tasks.c:5061  
97150,0x7010670C,0xF2C70310,97149,vTaskSwitchContext,tasks.c:5061  
97149,0x70106708,0xF2430340,97148,vTaskSwitchContext,tasks.c:5061  
97148,0x701001E0,0xE12FFF30,97147,HwiP\_svc\_handler,portASM.S:148  
97147,0x701001DC,0xE59F0168,97146,HwiP\_svc\_handler,portASM.S:147  
97146,0x701001D8,0xE581D000,97145,HwiP\_svc\_handler,portASM.S:146  
97145,0x701001D4,0xE5901000,97144,HwiP\_svc\_handler,portASM.S:146  
97144,0x701001D0,0xE59F016C,97143,HwiP\_svc\_handler,portASM.S:146  
97143,0x701001CC,0xE52D3004,97142,HwiP\_svc\_handler,portASM.S:146  
97142,0x701001C8,0x152D1004,97141,HwiP\_svc\_handler,portASM.S:146  
97141,0x701001C4,0x1D2D0B20,97140,HwiP\_svc\_handler,portASM.S:146  
97140,0x701001C0,0x1EF11A10,97139,HwiP\_svc\_handler,portASM.S:146  
97139,0x701001BC,0xE3530000,97138,HwiP\_svc\_handler,portASM.S:146  
97138,0x701001B8,0xE5923000,97137,HwiP\_svc\_handler,portASM.S:146  
97137,0x701001B4,0xE59F218C,97136,HwiP\_svc\_handler,portASM.S:146  
97136,0x701001B0,0xE92D5FFF,97135,HwiP\_svc\_handler,portASM.S:146  
97135,0x701001AC,0xF102001F,97134,HwiP\_svc\_handler,portASM.S:146  
97134,0x701001A8,0xF96D051F,97133,HwiP\_svc\_handler,portASM.S:146  
97133,0x00000008,0xE59FF018,97132,Supervisor call (SVC),\_vectors,HwiP\_armv7r\_vectors\_freertos\_asm.S:42  
97132,0x7010A0E2,0x0000DF00,97131,xQueueSemaphoreTake,queue.c:1804  
97131,0x7010A0E0,0x0000B900,97130,xQueueSemaphoreTake,queue.c:1802  
97130,0x70107A5A,0xE8BD8FF0,97129,xTaskResumeAll,tasks.c:4104  
97129,0x70107A58,0x0000B007,97128,xTaskResumeAll,tasks.c:4104  
97128,0x70107A56,0x00009802,97127,xTaskResumeAll,tasks.c:4104  
97127,0x70107034,0x0000BD30,97126,vTaskExitCritical,tasks.c:7076  
97126,0x70107032,0x0000B003,97125,vTaskExitCritical,tasks.c:7076  
97125,0x70107030,0x0000B662,97124,vEnableInterruptPriority,portmacro.h:195  
97124,0x7010702E,0x0000B903,97123,vTaskExitCritical,tasks.c:7056  
97123,0x7010702C,0x00006D4B,97122,vTaskExitCritical,tasks.c:7056  
97122,0x7010702A,0x00006553,97121,vTaskExitCritical,tasks.c:7054  
97121,0x70107028,0x00003B01,97120,vTaskExitCritical,tasks.c:7054  
97120,0x70107026,0x00006D53,97119,vTaskExitCritical,tasks.c:7054  
97119,0x70107024,0x00006821,97118,vTaskExitCritical,tasks.c:7056  
97118,0x70107022,0x00006822,97117,vTaskExitCritical,tasks.c:7054  
97117,0x70107020,0x0000B13B,97116,vTaskExitCritical,tasks.c:7052  
97116,0x7010701E,0x00006D5B,97115,vTaskExitCritical,tasks.c:7052  
97115,0x7010701C,0x00006823,97114,vTaskExitCritical,tasks.c:7052  
97114,0x802F068A,0x00004770,97113,\_DebugP\_assert,DebugP\_log.c:92  
97113,0x802F0688,0x0000B100,97112,\_DebugP\_assert,DebugP\_log.c:92  
97112,0x7015991C,0xE51FF004,97111,\_\_\_DebugP\_assert\_from\_arm,:?  
97111,0x70107018,0xF052EC80,97110,vTaskExitCritical,tasks.c:7050  
97110,0x70107016,0x00000940,97109,vTaskExitCritical,tasks.c:7050  
97109,0x70107012,0xFAB0F080,97108,vTaskExitCritical,tasks.c:7050  
97108,0x7010700E,0xF641338A,97107,vTaskExitCritical,tasks.c:7050  
97107,0x7010700A,0xF2C70110,97106,vTaskExitCritical,tasks.c:7050  
97106,0x70107008,0x00009300,97105,vTaskExitCritical,tasks.c:7050  
97105,0x70107004,0xF64531E0,97104,vTaskExitCritical,tasks.c:7050  
97104,0x70107002,0x00006808,97103,vTaskExitCritical,tasks.c:7050  
97103,0x70106FFE,0xF2C70210,97102,vTaskExitCritical,tasks.c:7050  
97102,0x70106FFA,0xF2C70310,97101,vTaskExitCritical,tasks.c:7050  
97101,0x70106FF6,0xF64852D8,97100,vTaskExitCritical,tasks.c:7050  
97100,0x70106FF2,0xF2C70110,97099,vTaskExitCritical,tasks.c:7050  
97099,0x70106FEE,0xF64663E4,97098,vTaskExitCritical,tasks.c:7050  
97098,0x70106FEA,0xF24301D0,97097,vTaskExitCritical,tasks.c:7050  
97097,0x802F068A,0x00004770,97096,\_DebugP\_assert,DebugP\_log.c:92  
97096,0x802F0688,0x0000B100,97095,\_DebugP\_assert,DebugP\_log.c:92  
97095,0x7015991C,0xE51FF004,97094,\_\_\_DebugP\_assert\_from\_arm,:?  
97094,0x7010610C,0x0000681B,97093,xTaskIncrementTick,tasks.c:4864  
97093,0x70106108,0xF2C70310,97092,xTaskIncrementTick,tasks.c:4864  
97092,0x70106104,0xF24303C8,97091,xTaskIncrementTick,tasks.c:4864  
97091,0x70106022,0x0000D36F,97090,xTaskIncrementTick,tasks.c:4715  
97090,0x7010601E,0xF04F0C00,97089,xTaskIncrementTick,tasks.c:4675  
97089,0x7010601C,0x0000BF38,97088,xTaskIncrementTick,tasks.c:4675  
97088,0x7010601A,0x00004598,97087,xTaskIncrementTick,tasks.c:4715  
97087,0x70106018,0x0000681B,97086,xTaskIncrementTick,tasks.c:4715  
97086,0x70106016,0x00009B05,97085,xTaskIncrementTick,tasks.c:4715  
97085,0x70106014,0x00009305,97084,prvResetNextTaskUnblockTime,tasks.c:6464  
97084,0x70106010,0xF2C70310,97083,prvResetNextTaskUnblockTime,tasks.c:6464  
97083,0x7010600C,0xF2430378,97082,prvResetNextTaskUnblockTime,tasks.c:6464  
97082,0x70105F9C,0x0000D136,97081,xTaskIncrementTick,tasks.c:4702  
97081,0x70105F98,0xF1B80F00,97080,xTaskIncrementTick,tasks.c:4702  
97080,0x70105F94,0xF8C38000,97079,xTaskIncrementTick,tasks.c:4700  
97079,0x70105F90,0xF1020801,97078,xTaskIncrementTick,tasks.c:4696  
97078,0x70105F8E,0x0000B087,97077,xTaskIncrementTick,tasks.c:4671  
97077,0x70105F8C,0x0000681A,97076,xTaskIncrementTick,tasks.c:4696  
97076,0x70105F88,0xE92D4FF0,97075,xTaskIncrementTick,tasks.c:4671  
97075,0x70105F84,0xF2C70310,97074,xTaskIncrementTick,tasks.c:4696  
97074,0x70105F80,0xF24303C4,97073,xTaskIncrementTick,tasks.c:4696  
97073,0x70107A16,0xF7FEFAB3,97072,xTaskIncrementTick,tasks.c:4055  
97072,0x70107A28,0x0000D0F5,97071,xTaskIncrementTick,tasks.c:4692  
97071,0x70107A26,0x00002B00,97070,xTaskIncrementTick,tasks.c:4692  
97070,0x70107A24,0x00006823,97069,xTaskIncrementTick,tasks.c:4692  
97069,0x70107A14,0x0000E006,97068,xTaskResumeAll,tasks.c:4055  
97068,0x70107A12,0x00002701,97067,xTaskResumeAll,tasks.c:4055  
97067,0x70107A0E,0xF8DD8010,97066,xTaskResumeAll,tasks.c:4055

---

<div class="post-metadata">

**Author:** ![rasty1](https://d3iykfbgfh8zhg.cloudfront.net/user_avatar/forums.freertos.org/rasty1/32/5886_2.png) [@rasty1](https://forums.freertos.org/u/rasty1)\
**Post date:** [December 22, 2025, 10:32am UTC](https://forums.freertos.org/t/stack-destroyed-after-return-from-long-vtaskdelay/24787/8 "2025-12-22T10:32:06Z")

</div>

here is stack frame (shown before and after CurrentTcb-\>PxTopOfStack.  
There is a correlation between value (red) 0x40100221 in R7 and its location in Frame and registers stored before and after R7 It seems that registers are stored at offset CurrentTcb-\>PxTopOfStack + 4 bytes. I do not have logical explanations for this offset (probably LR stored first?)

 ![image](https://d2v6vdsk2p900z.cloudfront.net/original/2X/e/e5c03fd4affa68279dd5f78d19cc663bea668e56.png)

incorrect value (0x40100221) is persistent - reproduces avery time, even if I change an app a little bit.

---

<div class="post-metadata">

**Author:** ![rasty1](https://d3iykfbgfh8zhg.cloudfront.net/user_avatar/forums.freertos.org/rasty1/32/5886_2.png) [@rasty1](https://forums.freertos.org/u/rasty1)\
**Post date:** [December 22, 2025, 5:04pm UTC](https://forums.freertos.org/t/stack-destroyed-after-return-from-long-vtaskdelay/24787/9 "2025-12-22T17:04:55Z")

</div>

It looks like problem is somewhere in \_fclose\_r. R7 gets corrupted somewhere inside this function.

---

<div class="post-metadata">

**Author:** ![aggarg](https://d3iykfbgfh8zhg.cloudfront.net/user_avatar/forums.freertos.org/aggarg/32/4245_2.png) [@aggarg](https://forums.freertos.org/u/aggarg)\
**Post date:** [December 22, 2025, 5:34pm UTC](https://forums.freertos.org/t/stack-destroyed-after-return-from-long-vtaskdelay/24787/10 "2025-12-22T17:34:16Z")

</div>

Are you writing any function in assembly? Can you share your complete code?

---

<div class="post-metadata">

**Author:** ![rasty1](https://d3iykfbgfh8zhg.cloudfront.net/user_avatar/forums.freertos.org/rasty1/32/5886_2.png) [@rasty1](https://forums.freertos.org/u/rasty1)\
**Post date:** [December 22, 2025, 5:45pm UTC](https://forums.freertos.org/t/stack-destroyed-after-return-from-long-vtaskdelay/24787/11 "2025-12-22T17:45:49Z")

</div>

No assembly.  
Problem is probably in libc \_retarget\_lock\* functions that do not do what I expect.  
I use Mutex and figured out that some \_retarget\_lock\* functions are called before main.

Is there FreeRTOS-friendly \_retarget\_lock\* implementation for libc ?

---

<div class="post-metadata">

**Author:** ![aggarg](https://d3iykfbgfh8zhg.cloudfront.net/user_avatar/forums.freertos.org/aggarg/32/4245_2.png) [@aggarg](https://forums.freertos.org/u/aggarg)\
**Post date:** [December 23, 2025, 4:57am UTC](https://forums.freertos.org/t/stack-destroyed-after-return-from-long-vtaskdelay/24787/12 "2025-12-23T04:57:45Z")

</div>

> [@rasty1](#):
>
> I use Mutex and figured out that some \_retarget\_lock\* functions are called before main.

Can you change your implementation to use mutex only after the scheduler is started:

```auto
if( xTaskGetSchedulerState() != taskSCHEDULER_NOT_STARTED )
{
       /* use mutex. */
}

```

---

<div class="post-metadata">

**Author:** ![rasty1](https://d3iykfbgfh8zhg.cloudfront.net/user_avatar/forums.freertos.org/rasty1/32/5886_2.png) [@rasty1](https://forums.freertos.org/u/rasty1)\
**Post date:** [December 23, 2025, 5:40am UTC](https://forums.freertos.org/t/stack-destroyed-after-return-from-long-vtaskdelay/24787/13 "2025-12-23T05:40:45Z")

</div>

that’s it!  
it is better then  
if (!xTaskGetCurrentTaskHandle()) /\* not in task \*/  
{  
return;  
}

---

<div class="post-metadata">

**Author:** ![aggarg](https://d3iykfbgfh8zhg.cloudfront.net/user_avatar/forums.freertos.org/aggarg/32/4245_2.png) [@aggarg](https://forums.freertos.org/u/aggarg)\
**Post date:** [December 23, 2025, 5:55pm UTC](https://forums.freertos.org/t/stack-destroyed-after-return-from-long-vtaskdelay/24787/14 "2025-12-23T17:55:53Z")

</div>

Great! So this fixes your problem, right?

---

<div class="post-metadata">

**Author:** ![rasty1](https://d3iykfbgfh8zhg.cloudfront.net/user_avatar/forums.freertos.org/rasty1/32/5886_2.png) [@rasty1](https://forums.freertos.org/u/rasty1)\
**Post date:** [December 23, 2025, 6:13pm UTC](https://forums.freertos.org/t/stack-destroyed-after-return-from-long-vtaskdelay/24787/15 "2025-12-23T18:13:32Z")

</div>

unfortunaty not yet. problem is somewhere on stitch between libc and freertos.  
any modification/instrumentation to problematic code and problem goes away.  
i’ll post results , but it may take time.  
the funny thing that i didnt find any glue code for libc that looks good and is not being criticized.

---

<div class="post-metadata">

**Author:** ![rasty1](https://d3iykfbgfh8zhg.cloudfront.net/user_avatar/forums.freertos.org/rasty1/32/5886_2.png) [@rasty1](https://forums.freertos.org/u/rasty1)\
**Post date:** [December 24, 2025, 6:04am UTC](https://forums.freertos.org/t/stack-destroyed-after-return-from-long-vtaskdelay/24787/16 "2025-12-24T06:04:18Z")

</div>

I think that I found direction.  
In the newer version of FreeRTOS port of TI  
I see that configUSE\_NEWLIB\_REENTRANT is abandoned and configUSE\_C\_RUNTIME\_TLS\_SUPPORT do something similar.  
**It would be nice if they could keep the same heuristics if configUSE\_NEWLIB\_REENTRANT is enabled.**

So setting configUSE\_NEWLIB\_REENTRANT (which is still in FreeRTOS.h) to 1 makes no effect.  
instead  
#ifndef configSET\_TLS\_BLOCK  
#define configSET\_TLS\_BLOCK( xTLSBlock ) ( \_impure\_ptr = &( xTLSBlock ) )  
#endif

UPDATE: there is the same heuristics, configSET\_TLS\_BLOCK depends on configUSE\_NEWLIB\_REENTRANT. indirectly.  
I enable it and keep fingers crossed.  
UPDATE 1:  
I recall why it was not defined, because in TI RTOS wrappers they use hardcoded TCB size  
/\*\* Minimum requirement for FreeRTOS MPU Port to work

- In this case, TCB stores the MPU settings including system mode stack as well the task context. \*/  
#define TaskP\_OBJECT\_SIZE\_MAX (4568u)  
#else  
#define TaskP\_OBJECT\_SIZE\_MAX (180u)  
#endif  
and system load stops in some ASSERT.

---

<div class="post-metadata">

**Author:** ![rasty1](https://d3iykfbgfh8zhg.cloudfront.net/user_avatar/forums.freertos.org/rasty1/32/5886_2.png) [@rasty1](https://forums.freertos.org/u/rasty1)\
**Post date:** [December 24, 2025, 6:08pm UTC](https://forums.freertos.org/t/stack-destroyed-after-return-from-long-vtaskdelay/24787/17 "2025-12-24T18:08:47Z")

</div>

UPDATE2:  
It appears that configUSE\_NEWLIB\_REENTRANT is not enough.  
Need also to rewrite \_\_sfp\_lock\_acquire and \_\_sfp\_lock\_release, which is bit more tricky, since these symbols are defined as “strong” in newlib and maybe also a bunch of functions that start with \_\_retarget\_lock\*

---

<div class="post-metadata">

**Author:** ![rasty1](https://d3iykfbgfh8zhg.cloudfront.net/user_avatar/forums.freertos.org/rasty1/32/5886_2.png) [@rasty1](https://forums.freertos.org/u/rasty1)\
**Post date:** [December 25, 2025, 1:25pm UTC](https://forums.freertos.org/t/stack-destroyed-after-return-from-long-vtaskdelay/24787/18 "2025-12-25T13:25:49Z")

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Final verdict  
configUSE\_NEWLIB\_REENTRANT plus \_\_sfp\_lock\_acquire and \_\_sfp\_lock\_release

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**Author:** ![dc42](https://d3iykfbgfh8zhg.cloudfront.net/user_avatar/forums.freertos.org/dc42/32/487_2.png) [@dc42](https://forums.freertos.org/u/dc42)\
**Post date:** [December 31, 2025, 8:05am UTC](https://forums.freertos.org/t/stack-destroyed-after-return-from-long-vtaskdelay/24787/19 "2025-12-31T08:05:27Z")

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I’m glad you got it working.

In our embedded system the additional per-task storage that configUSE\_NEWLIB\_REENTRANT causes was unafffordable. Instead we designed our software to avoid using any library functions that uses impure\_ptr. This required:

- Writing our own versions of printf and similar functions. Doing this also allowed us to printf to our own data structures and add facilities for JSON escaping. The printf code in newlib is quite complicated because it handles all representable floating pint values; however if your application doesn’t need to print values that are always correct to the very last digit then a simpler implementation will suffice.
- Writing our own versions of strtod and related functions. Again, the newlib version handles all representable values, but if your application doesn’t need to handle extreme values accurately then a simpler version is possible.
- Several standard library functions such as gmtime return a pointer to a static buffer, which is in the area pointed to by impure\_ptr. However, gcc provides alternative versions of these functions such as gmtime\_r where you supply the buffer; so we use those instead.

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**Author:** ![aggarg](https://d3iykfbgfh8zhg.cloudfront.net/user_avatar/forums.freertos.org/aggarg/32/4245_2.png) [@aggarg](https://forums.freertos.org/u/aggarg)\
**Post date:** [December 31, 2025, 8:48am UTC](https://forums.freertos.org/t/stack-destroyed-after-return-from-long-vtaskdelay/24787/20 "2025-12-31T08:48:50Z")

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Glad that you worked it out!

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