Posted by andreaspiezia on 2019-05-11 19:28

Hi all,
I’m run a project that use printf with:
Eclipse IDE for C/C++ Developers
Version: Neon.3 Release (4.6.3)
Build id: 20170314-1500

If I add -u _printf_float to linker flags I’ve error from compiler: (to print floating)

Invoking: MCU GCC Linker
arm-none-eabi-gcc -mcpu=cortex-m4 -mthumb -mfloat-abi=hard -mfpu=fpv4-sp-d16 -specs=nosys.specs -specs=nano.specs -u _printf_float -T”../STM32F401RETx_FLASH.ld” -Wl,-Map=output.map -Wl,--gc-sections -o “NucleoF401RE_53L1_Expansion.elf” @”objects.list” -lm
Application/SW4STM32/syscalls.o: In function `_sbrk’:
C:/en.X-CUBE-53L1A1/STM32CubeExpansion_53L1A1_V2.1.0/Projects/STM32F401RE-Nucleo/Examples/53L1A1/SimpleRanging/SW4STM32/syscalls.c:135: undefined reference to `end’
collect2.exe: error: ld returned 1 exit status
makefile:37: recipe for target ‘NucleoF401RE_53L1_Expansion.elf’ failed
make: *** NucleoF401RE_53L1_Expansion.elf Error 1

If I don’t add -u _printf_float to linker flags it compile with no errors:
make all
Building target: NucleoF401RE_53L1_Expansion.elf
Invoking: MCU GCC Linker
arm-none-eabi-gcc -mcpu=cortex-m4 -mthumb -mfloat-abi=hard -mfpu=fpv4-sp-d16 -specs=nosys.specs -specs=nano.specs -T”../STM32F401RETx_FLASH.ld” -Wl,-Map=output.map -Wl,--gc-sections -o “NucleoF401RE_53L1_Expansion.elf” @”objects.list” -lm
Finished building target: NucleoF401RE_53L1_Expansion.elf

make --no-print-directory post-build
Generating hex and Printing size information:
arm-none-eabi-objcopy -O ihex “NucleoF401RE_53L1_Expansion.elf” “NucleoF401RE_53L1_Expansion.hex”
arm-none-eabi-size “NucleoF401RE_53L1_Expansion.elf”
text data bss dec hex filename
8 0 0 8 8 NucleoF401RE_53L1_Expansion.elf