arm-none-eabi-ld malloc undefined reference

Question

I'm working on some code for Texas Instruments' Tiva C Series TMC123G Launchpad (an ARM Cortex M4 MCU board), my code doesn't compile due to a undefined reference to 'malloc'. startup_gcc.c and project.ld are part of TivaWare. Equivalent files can be found here:

/src/startup_gcc.c
/TM4C123GH6PM.ld

Here my console output when building:

arm-none-eabi-gcc -o build/minimal.o src/minimal.c -g -mthumb -mcpu=cortex-m4 -mfpu=fpv4-sp-d16 -mfloat-abi=softfp -Os -ffunction-sections -fdata-sections -MD -std=c99 -Wall -pedantic -DPART_TM4C123GH6PM -c -DTARGET_IS_BLIZZARD_RA1 -Dgcc -DF_CPU=80000000L -Isrc -Ilibraries -I/home/jakob/opt/tivaware
arm-none-eabi-gcc -o build/startup_gcc.o /home/jakob/opt/tivaware/examples/project/startup_gcc.c -g -mthumb -mcpu=cortex-m4 -mfpu=fpv4-sp-d16 -mfloat-abi=softfp -Os -ffunction-sections -fdata-sections -MD -std=c99 -Wall -pedantic -DPART_TM4C123GH6PM -c -DTARGET_IS_BLIZZARD_RA1 -Dgcc - DF_CPU=80000000L -Isrc -Ilibraries -I/home/jakob/opt/tivaware
arm-none-eabi-ld -o build/a.out build/minimal.o build/startup_gcc.o -T /home/jakob/opt/tivaware/examples/project/project.ld --entry ResetISR --gc-sections
build/minimal.o: In function `Struct_begin':
/home/jakob/TivaMallocProblemMini/src/minimal.c:29: undefined reference to `malloc'
Makefile:66: recipe for target 'build/a.out' failed
make: *** [build/a.out] Error 1

Here is a minimal example of the problem, ~~the malloc in the main function does not seem to cause any problems, only the one in the Struct_begin function.~~ (It was optimized away.)

#include <stdint.h>
#include <stdbool.h>
#include <stdlib.h>

typedef struct s_Struct
{
    int16_t param;
} Struct;

Struct* Struct_begin(int16_t param);

int main() {
    Struct* s;

    s = malloc(sizeof(Struct));
    free(s);

    s = Struct_begin(10);
    s->param=0;

    for(;;);

    return EXIT_SUCCESS;
}

Struct* Struct_begin(int16_t param) {
    Struct* s;

    s = malloc(sizeof(Struct));
    s->param = param;

    return s;
}

github.com/dwelch67/tivac_launchpad has some bare metal examples for the tiva c launchpads. Not sure what problem you are really trying to solve here (why would you ever malloc on a microcontroller) but these very simple examples provide makefiles and such to get a working binary for these microcontrollers. — old_timer
Is there a better way to get a pointer on a struct, always happy to learn more. — Jakob Klepp
just declare the struct not a pointer to it, this is embedded bare metal code not an operating system — old_timer

doron doron · Accepted Answer · 2014-10-14T12:51:50

You are working on an embedded platform. In these circumstances, GCC (or rather ld) may not automatically link to a standard C library. You might need to explicitly need to link to the platform's standard library or you might need to supply your own implementation of malloc.

arm-none-eabi-ld malloc undefined reference

1 Answers