基于Limifrog STM32L board examples，我正在尝试为ARM开发设置自己的工具链（基于STM32F40x） .

我收到一个错误：

C:\Users\pmu\embedded\empty_stm32>make
arm-none-eabi-gcc  -mthumb -mcpu=cortex-m4 -mfloat-abi=hard -mfpu=fpv4-sp-d16 -I
./inc -I./../Libraries/CMSIS/Device/ST/STM32F4xx/Include -I./../Libraries/CMSIS/
Include -Os -Wall -ffunction-sections -fdata-sections -fno-exceptions -Wno-write
-strings -o main src/main.c
c:/program files (x86)/gnu tools arm embedded/4.9 2015q3/bin/../lib/gcc/arm-none
-eabi/4.9.3/../../../../arm-none-eabi/lib/armv7e-m/fpu\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
make: *** [main] Error 1

编译时：

#include "My_Globals.h"

int main(void) {

  while(1) {

  }

  return 0;
}

这个错误是什么意思？为什么不在上面的董事会例子中出现？

Makefile

# Compilation Tools
CC      = arm-none-eabi-gcc
LD      = arm-none-eabi-ld
CP      = arm-none-eabi-objcopy
OD      = arm-none-eabi-objdump
SIZE    = arm-none-eabi-size

# Optimization (ß,1,2,s)
OPT = s

ROOT        = ./..
CMSIS_DIR   = $(ROOT)/Libraries/CMSIS
HAL_DIR     = $(ROOT)/Libraries/CMSIS/Include
SRC         = ./src
INC_LOCAL  = ./inc

INCLUDES   =  \
    $(INC_LOCAL) \
    $(CMSIS_DIR)/Device/ST/STM32F4xx/Include \
    $(CMSIS_DIR)/Include

ARCH_FLAGS = -mthumb -mcpu=cortex-m4 -mfloat-abi=hard -mfpu=fpv4-sp-d16

LD_FLAGS   = 

# Compiler flags
CFLAGS =  \
    $(ARCH_FLAGS) \
    $(addprefix -I,$(INCLUDES)) \
    -O$(OPT) \
    -Wall \
    -ffunction-sections \
    -fdata-sections \
    -fno-exceptions \
    -Wno-write-strings

main:
    @echo "start"
    @echo $@
    $(CC) $(LDFLAGS) $(CFLAGS) -o $@ src/main.c

现在，可以使用哪些库从其他地方重用_exit（）的实现？

c arm stm32