# Better Firmware with LLVM/Clang | Interrupt

**URL:** <https://community.memfault.com/t/better-firmware-with-llvm-clang-interrupt/195>\
**Category:** Blog\
**Created:** [May 20, 2020, 5:59am UTC](https://community.memfault.com/t/better-firmware-with-llvm-clang-interrupt/195 "2020-05-20T05:59:25Z")\
**Posts on this page:** 1\
**Showing post:** 32

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**Author:** ![chrisc](https://yyz2.discourse-cdn.com/flex030/user_avatar/community.memfault.com/chrisc/32/22_2.png) [@chrisc](https://community.memfault.com/u/chrisc)\
**Post date:** [November 22, 2020, 10:22pm UTC](https://community.memfault.com/t/better-firmware-with-llvm-clang-interrupt/195/32 "2020-11-22T22:22:32Z")

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Hi @apullin, one idea would be to try would be adding `--ffunction-sections` & `--fdata-sections` to your compiler flags. Without these flags, unused dependencies will get pulled into your build and could be the cause of the undefined symbol errors you were seeing.

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