Undefined reference to `_exit'

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Verbose mode can be enabled via `-v, --verbose` option
CONFIGURATION: https://docs.platformio.org/page/boards/ststm32/black_f407zg.html
PLATFORM: ST STM32 (15.4.1) > Black STM32F407ZG
HARDWARE: STM32F407ZGT6 168MHz, 128KB RAM, 1MB Flash
DEBUG: Current (blackmagic) External (blackmagic, cmsis-dap, jlink, stlink)     
PACKAGES:
 - toolchain-gccarmnoneeabi @ 1.70201.0 (7.2.1)
LDF: Library Dependency Finder -> https://bit.ly/configure-pio-ldf
LDF Modes: Finder ~ chain, Compatibility ~ soft
Found 0 compatible libraries
Scanning dependencies...
No dependencies
Building in debug mode
Compiling .pio\build\genericSTM32F407ZGTx\src\Core\Src\gpio.o
Compiling .pio\build\genericSTM32F407ZGTx\src\Core\Src\main.o
Compiling .pio\build\genericSTM32F407ZGTx\src\Core\Src\stm32f4xx_hal_msp.o
Compiling .pio\build\genericSTM32F407ZGTx\src\Core\Src\stm32f4xx_it.o     
Compiling .pio\build\genericSTM32F407ZGTx\src\Core\Src\system_stm32f4xx.o
Compiling .pio\build\genericSTM32F407ZGTx\src\Drivers\STM32F4xx_HAL_Driver\Src\stm32f4xx_hal.o
Compiling .pio\build\genericSTM32F407ZGTx\src\Drivers\STM32F4xx_HAL_Driver\Src\stm32f4xx_hal_cortex.o
Compiling .pio\build\genericSTM32F407ZGTx\src\Drivers\STM32F4xx_HAL_Driver\Src\stm32f4xx_hal_dma.o   
Compiling .pio\build\genericSTM32F407ZGTx\src\Drivers\STM32F4xx_HAL_Driver\Src\stm32f4xx_hal_dma_ex.o
Compiling .pio\build\genericSTM32F407ZGTx\src\Drivers\STM32F4xx_HAL_Driver\Src\stm32f4xx_hal_exti.o 
Compiling .pio\build\genericSTM32F407ZGTx\src\Drivers\STM32F4xx_HAL_Driver\Src\stm32f4xx_hal_flash.o
Compiling .pio\build\genericSTM32F407ZGTx\src\Drivers\STM32F4xx_HAL_Driver\Src\stm32f4xx_hal_flash_ex.o
Compiling .pio\build\genericSTM32F407ZGTx\src\Drivers\STM32F4xx_HAL_Driver\Src\stm32f4xx_hal_flash_ramfunc.o
Compiling .pio\build\genericSTM32F407ZGTx\src\Drivers\STM32F4xx_HAL_Driver\Src\stm32f4xx_hal_gpio.o
Compiling .pio\build\genericSTM32F407ZGTx\src\Drivers\STM32F4xx_HAL_Driver\Src\stm32f4xx_hal_pwr.o
Compiling .pio\build\genericSTM32F407ZGTx\src\Drivers\STM32F4xx_HAL_Driver\Src\stm32f4xx_hal_pwr_ex.o
Compiling .pio\build\genericSTM32F407ZGTx\src\Drivers\STM32F4xx_HAL_Driver\Src\stm32f4xx_hal_rcc.o
Compiling .pio\build\genericSTM32F407ZGTx\src\Drivers\STM32F4xx_HAL_Driver\Src\stm32f4xx_hal_rcc_ex.o
Compiling .pio\build\genericSTM32F407ZGTx\src\Drivers\STM32F4xx_HAL_Driver\Src\stm32f4xx_hal_tim.o
Compiling .pio\build\genericSTM32F407ZGTx\src\Drivers\STM32F4xx_HAL_Driver\Src\stm32f4xx_hal_tim_ex.o
Compiling .pio\build\genericSTM32F407ZGTx\src\startup_stm32f407xx.o
Linking .pio\build\genericSTM32F407ZGTx\firmware.elf
d:/devel/platformio/packages/toolchain-gccarmnoneeabi/bin/../lib/gcc/arm-none-eabi/7.2.1/../../../../arm-none-eabi/lib/thumb/v7e-m\libc.a(lib_a-exit.o): In function `exit':
exit.c:(.text.exit+0x16): undefined reference to `_exit'  
collect2.exe: error: ld returned 1 exit status
*** [.pio\build\genericSTM32F407ZGTx\firmware.elf] Error 1
=================================================================== [FAILED] Took 1.67 seconds ===================================================================

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2

I think it’s missing nano.specs, you only have nosys.specs. Put the pio-gd32f350cb/add_nanolib.py at main · maxgerhardt/pio-gd32f350cb · GitHub in the root of your project and add extra_scripts = add_nanolib.py in the platformio.ini .

1 Like
3

Thank you, it worked.

4

I had the same error, in similar STM32 bare metal project. The suggestion from @maxgerhardt solves it, but I’d like to have a bit more understanding of what is going on…
@maxgerhardt , can you briefly explain why this error and why the extra linker flags solve it ?

If you have an empty bare metal project, who/what is calling _exit() ?

Thanks!