AVR-GCC Makefile 链接问题答案

【问题标题】：AVR-GCC Makefile Linking IssueAVR-GCC Makefile 链接问题
【发布时间】：2016-10-19 10:15:56
【问题描述】：

我有以下 Makefile：

# Name: Makefile
# Author: <insert your name here>
# Copyright: <insert your copyright message here>
# License: <insert your license reference here>

# DEVICE ....... The AVR device you compile for
# CLOCK ........ Target AVR clock rate in Hertz
# OBJECTS ...... The object files created from your source files. This list is
#                usually the same as the list of source files with suffix ".o".
# PROGRAMMER ... Options to avrdude which define the hardware you use for
#                uploading to the AVR and the interface where this hardware
#                is connected.
# FUSES ........ Parameters for avrdude to flash the fuses appropriately.

CSRC       = main.c Sys_init.c BB_Timers.c SPI.c Radio_interface.c  
DEVICE     = atmega328p 
MCU        = m328p 
CLOCK      = 800000
PROGRAMMER = -c dragon_isp 
PORT       = -P usb 
#PROGRAMMER = -c /dev/buspirate 
OBJECTS    = main.o 
FUSES      = -U efuse:w:0xff:m -U lfuse:w:0xe2:m -U hfuse:w:0xde:m
OBJECTS    = $(CSRC:.c=.o) $(ASRC:.s=.o)


######################################################################
######################################################################

# Tune the lines below only if you know what you are doing:

AVRDUDE = avrdude $(PROGRAMMER) $(PORT) -p $(DEVICE) -vv
COMPILE = avr-gcc -Wall -Os -DF_CPU=$(CLOCK) -mmcu=$(DEVICE) # symbolic targets:
all:    main.hex

.c.o:
    $(COMPILE) -c $< -o $@

.S.o:
    $(COMPILE) -x assembler-with-cpp -c $< -o $@
# "-x assembler-with-cpp" should not be necessary since this is the default
# file type for the .S (with capital S) extension. However, upper case
# characters are not always preserved on Windows. To ensure WinAVR
# compatibility define the file type manually.

.c.s:
    $(COMPILE) -S $< -o $@

flash:  all
    $(AVRDUDE) -U flash:w:main.hex:i

fuse:
    $(AVRDUDE) $(FUSES)

install: flash fuse

# if you use a bootloader, change the command below appropriately:
load: all
    bootloadHID main.hex

clean:
    rm -f main.hex main.elf $(OBJECTS)

# file targets:
main.elf: $(OBJECTS)
    $(COMPILE) -o main.elf $(OBJECTS)

main.hex: main.elf
    rm -f main.hex
    avr-objcopy -j .text -j .data -O ihex main.elf main.hex
# If you have an EEPROM section, you must also create a hex file for the
# EEPROM and add it to the "flash" target.

# Targets for code debugging and analysis:
disasm: main.elf
    avr-objdump -d main.elf

cpp:
    $(COMPILE) -E main.c

当我使用make 编译时，我收到以下错误：

>> make    
avr-gcc -Wall -Os -DF_CPU=800000 -mmcu=atmega328p   -o main.elf main.o Sys_init.o BB_Timers.o SPI.o Radio_interface.o 
    Sys_init.o: In function `System_init':
    Sys_init.c:(.text+0x0): undefined reference to `One'
    Sys_init.c:(.text+0x2): undefined reference to `One'
    BB_Timers.o: In function `__vector_14':
    BB_Timers.c:(.text+0x2e): undefined reference to `One'
    BB_Timers.c:(.text+0x30): undefined reference to `One'
    collect2: error: ld returned 1 exit status
    make: *** [Makefile:66: main.elf] Error 1

我尝试过改组CSRC 的顺序，以前似乎有所作为，但这次不行。不过我觉得这是错误的，因为拥有许多源文件的人将如何为一个大项目处理这个问题？一定有更好的办法。

【问题讨论】：

什么是One，它在哪里定义？
➭ grep -rn "One" bb_system.h:25:extern struct bb_system One; Sys_init.c:7://struct bb_system One; Sys_init.c:23: BB_Struct_init(&One); Binary file Sys_init.o matches BB_Timers.c:31: One.sys_count++; //this will provide the count for taks BB_Timers.c:37: return (One.sys_count++;); Binary file BB_Timers.o matches
所以One 实际上并没有在任何地方定义，只是声明和使用？唯一的定义似乎被注释掉了。
好像是我在这里定义的吧？ bb_system.h:25:extern struct bb_system One;
@BrocolliRob 不，这是一个声明。在第 7 行的 Sys_init.c 中，您有一个 注释掉 定义。

标签： c gcc makefile compilation avr

【解决方案1】：

所以总结一下这个问题的cmets：

在第 25 行的 bb_system.h 中，您输入了以下语句：

extern struct bb_system One;

这意味着在你编译的文件中的某处必须有一个名为One 的变量struct bb_system

在第 7 行的 Sys_init.c 中，您注释掉了该声明

// struct bb_system One;

它可能会解决。

修复那条线

【讨论】：