# Free RTOS incompatible with reentrant newlib?

**URL:** <https://forums.freertos.org/t/free-rtos-incompatible-with-reentrant-newlib/4710>\
**Category:** Kernel\
**Created:** [August 14, 2011, 10:07am UTC](https://forums.freertos.org/t/free-rtos-incompatible-with-reentrant-newlib/4710 "2011-08-14T10:07:27Z")\
**Posts on this page:** 3\
**Page:** 1

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**Author:** ![system](https://d2v6vdsk2p900z.cloudfront.net/original/1X/7fc8fdb729c645aab5b20282bbe34e57cb407be6.jpeg) [@system](https://forums.freertos.org/u/system)\
**Post date:** [August 14, 2011, 10:07am UTC](https://forums.freertos.org/t/free-rtos-incompatible-with-reentrant-newlib/4710/1 "2011-08-14T10:07:27Z")

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**[ten-techhunter](https://sourceforge.net/u/ten-techhunter/)** wrote on [Sunday, August 14, 2011](https://sourceforge.net/p/freertos/discussion/382005/thread/d101b783/#0d6b):

While I know this is similar to my other thread, I really want that thread to focus on which C Standard Libraries people are using, and why. I’d like to focus here on the compatibility issue I found in a web search with reentrant newlib and Yagarto. Is this an incompatibility that prevents Yagarto from shipping with fully reentrant newlib to this day? Is it not possible to use a fully reentrant C Standard Library with Free RTOS?

An example of the issue in question is here: [https://sourceforge.net/projects/freertos/forums/forum/382005/topic/3234440](https://sourceforge.net/projects/freertos/forums/forum/382005/topic/3234440)

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**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, 10:29am UTC](https://forums.freertos.org/t/free-rtos-incompatible-with-reentrant-newlib/4710/2 "2011-08-14T10:29:16Z")

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**[rtel](https://sourceforge.net/u/rtel/)** wrote on [Sunday, August 14, 2011](https://sourceforge.net/p/freertos/discussion/382005/thread/d101b783/#22ec):

I don’t think the link you provided has anything to do with reentrancy as such, it is more to do with the application dependent functions that newlib expects you to provide yourself.&nbsp; With reference to reentrancy, I was referring more to newlibs use of struct \_reent, as described here: [http://vmlinux.org/crash/mirror/www.objsw.com/docs/libc\_127.html](http://vmlinux.org/crash/mirror/www.objsw.com/docs/libc_127.html)

If you search this forum, or the web, you will (maybe) find some modifications to FreeRTOS done by a third party to add the necessary pointer into the FreeRTOS task TCB.

Regards.

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**Author:** ![system](https://d2v6vdsk2p900z.cloudfront.net/original/1X/7fc8fdb729c645aab5b20282bbe34e57cb407be6.jpeg) [@system](https://forums.freertos.org/u/system)\
**Post date:** [August 14, 2011, 9:10pm UTC](https://forums.freertos.org/t/free-rtos-incompatible-with-reentrant-newlib/4710/3 "2011-08-14T21:10:45Z")

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**[ten-techhunter](https://sourceforge.net/u/ten-techhunter/)** wrote on [Sunday, August 14, 2011](https://sourceforge.net/p/freertos/discussion/382005/thread/d101b783/#c5b5):

Your answers are a bit too subtle for me. Are you saying that standard FreeRTOS is incompatible with standard reentrant newlib? Are there other fully reentrant C Standard Libraries that don’t have this problem?