exit.c:(.text+0x18): undefined reference to `_exit' when using arm-none-eabi-gcc

Question

I\'m new to the field of microcontrollers. I need to port an IDE which is compiling programs for AVR microcontrollers to compile programs for ARM microcontrollers. I have ju

Answer 1

This happens when compiling a file with arm-none-eabi-gcc in one machine/architecture to load it in an ARM target machine. Most probably you are not making use of semihosting, you want to retarget.

ARM® Compiler toolchain Version 4.1 indicates:

Semihosting is a mechanism that enables code running on an ARM target to communicate and use the Input/Output facilities on a host computer that is running a debugger.

From the toolchain's readme.txt (under folder .../gcc-arm-none-eabi-VERSION/share/doc/gcc-arm-none-eabi):

** non-semihosting/retarget

If you are using retarget, linking like: $ arm-none-eabi-gcc --specs=nosys.specs $(OTHER_LINK_OPTIONS)

For me --specs=nosys.specs was enough ;)

Answer 2

Use --specs=nosys.specs:

arm-none-eabi-gcc --specs=nosys.specs $(OTHER_LINK_OPTIONS)

Reference:

• ARM Options
• GNU Tools for ARM Embedded Processors

Answer 3

I had the same problem. The solution was as follows:

• Add options -ffreestanding -flto into compiler call line.
• And add options -flto -ffreestanding -nostdlib into linker call line.