当我尝试编译时出现此错误：boot.s:18: multiple definition of `_start';

如何解决当我尝试编译时出现此错误：boot.s:18: multiple definition of `_start';

我正在尝试为 raspberry pi 创建自己的操作系统，但是每当我尝试使用 ARM win32 交叉编译器使用 make 文件编译它时，我都会收到此错误：

c:/superpi/superpios/build/gcc-arm-none-eabi-10-2020-q4-major-win32/bin/../lib/gcc/arm-none-eabi/10.2.1/../../../../arm-none-eabi/bin/ld.exe: objects/boot.o: in function `_start':
C:\SuperPi\SuperPiOS\build/../src/kernel/boot.s:18: multiple definition of `_start'; objects/boot.o:C:\SuperPi\SuperPiOS\build/../src/kernel/boot.s:18: first defined here
collect2.exe: error: ld returned 1 exit status
make: *** [Makefile:54: build] Error 1

我尝试通过删除以下内容来修复它：.globl _start 但这似乎不起作用，它只是给了我另一个错误说：

gcc-arm-none-eabi-10-2020-q4-major-win32/bin/../lib/gcc/arm-none-eabi/10.2.1/../../../../arm-none-eabi/bin/ld.exe: warning: cannot find entry symbol _start; defaulting to 00008000

这是 boot.s 脚本：

.equ KERNEL_STACK_SIZE,4096
// To keep this in the first portion of the binary.

.section ".text.boot"
// Make _start global.

// Entry point for the kernel.
// r15 -> should begin execution at 0x8000.
// r0 -> 0x00000000
// r1 -> 0x00000C42
// r2 -> 0x00000100 - start of ATAGS
// preserve these registers as argument for kernel_main
.globl _start
_start:
    // This set of instructions sets 3 of the 4 cores to go to halt.
    // Model 1 only has 1 cpu and does not have this instruction,so don't include it if building for model 1
#ifndef MODEL_1
    mrc p15,#0,r1,c0,#5
    and r1,#3
    cmp r1,#0
    bne halt
#endif
    // Setup the stack.  Stack will be 32 KB above kernel image
    ldr sp,=__end
    mov r4,#(KERNEL_STACK_SIZE)
    add sp,sp,r4

    // Clear out bss.
    ldr r4,=__bss_start
    ldr r9,=__bss_end
    mov r5,#0
    mov r6,#0
    mov r7,#0
    mov r8,#0
    b       2f

1:
    // store multiple at r4.
    stmia r4!,{r5-r8}

// If we are still below bss_end,loop.
2:
    cmp r4,r9
    blo 1b

    // Call kernel_main
    mov r2,#0x100
    bl kernel_main
    b halt

// halt
halt:
    wfe
    b halt

哦，这是生成文件：

# Don't use normal gcc,use the arm cross compiler
TOOLCHAIN = ./gcc-arm-none-eabi-10-2020-q4-major-win32/bin/arm-none-eabi
CC = $(TOOLCHAIN)-gcc
OBJCOPY = $(TOOLCHAIN)-objcopy
GDB = $(TOOLCHAIN)-gdb


# Set any constants based on the raspberry pi model.  Version 1 has some differences to 2 and 3
ifeq ($(RASPI_MODEL),4)
    CPU = arm1176jzf-s
    DIRECTIVES = -D MODEL_4
    ARCHDIR = model4
else
    CPU = cortex-a7
    ARCHDIR = model2
endif

CFLAGS= -mcpu=$(CPU) -fpic -ffreestanding $(DIRECTIVES) -g
CXXFLAGS= -ggdb3 -O0
CSRCFLAGS= -O2 -Wall -Wextra
LFLAGS= -ffreestanding -O2 -nostdlib
ASMCFLAGS= -f elf32 -F dwarf -g -w+all
ASM= -s

# Location of the files
KER_SRC = ../src/kernel
KER_MENU_SRC = ../src/kernel/menu
KER_HEAD = ../include
COMMON_SRC = ../src/common
UI_IMAGES = ..images/ui
OBJ_DIR = objects
ASMSOURCES = $(wildcard $(KER_SRC)/*.s)
KERSOURCES = $(wildcard $(KER_SRC)/*.c)
#KERSOURCES = $(wildcard $(KER_SRC)/$(ARCHDIR)/*.c)
COMMONSOURCES = $(wildcard $(COMMON_SRC)/*.c)
KERSOURCESCPP = $(wildcard $(KER_SRC)/*.cpp)
#KERSOURCESCPP = $(wildcard $(KER_SRC)/$(ARCHDIR)/*.cpp)
#KERMENUSOURCESC = $(wildcard $(KER_MENU_SRC)/*.c)
#KERMENUSOURCESCPP = $(wildcard $(KER_MENU_SRC)/*.cpp)
UISOURCES = $(wildcard $(UI_IMAGES)/*.png)
OBJECTS = $(patsubst $(KER_SRC)/%.s,$(OBJ_DIR)/%.o,$(ASMSOURCES))
OBJECTS += $(patsubst $(KER_SRC)/%.s,$(ASMSOURCES))
OBJECTS += $(patsubst $(KER_SRC)/%.c,$(KERSOURCES))
OBJECTS += $(patsubst $(KER_SRC)/%.cpp,$(KERSOURCESCPP))
OBJECTS += $(patsubst $(COMMON_SRC)/%.c,$(COMMONSOURCES))
#OBJECTS += $(patsubst $(KER_MENU_SRC)/%.c,$(KERMENUSOURCESC))
#OBJECTS += $(patsubst $(KER_MENU_SRC)/%.cpp,$(KERMENUSOURCESCPP))
OBJECTS += $(patsubst $(UI_IMAGES)/%.png,$(UISOURCES))
HEADERS = $(wildcard $(KER_HEAD)/*.h)

IMG_NAME=SuperPiOS

build: $(OBJECTS) $(HEADERS)
    $(CC) -T linker.ld -o $(IMG_NAME).elf $(LFLAGS) $(OBJECTS)
    $(OBJCOPY) $(IMG_NAME).elf -O binary $(IMG_NAME).img

$(OBJ_DIR)/%.o: $(KER_SRC)/%.s
    mkdir -p $(@D)
    $(CC) $(CFLAGS) -I$(KER_SRC) -c $< -o $@

$(OBJ_DIR)/%.o: $(KER_SRC)/%.c
    mkdir -p $(@D)
    $(CC) $(CFLAGS) -I$(KER_SRC) -I$(KER_HEAD) -c $< -o $@ $(CSRCFLAGS)

$(OBJ_DIR)/%.o: $(KER_SRC)/$(ARCHDIR)/%.c
    mkdir -p $(@D)
    $(CC) $(CFLAGS) -I$(KER_SRC) -I$(KER_HEAD) -c $< -o $@ $(CSRCFLAGS)

$(OBJ_DIR)/%.o: $(KER_SRC)/%.cpp
    mkdir -p $(@D)
    $(CC) $(CXXFLAGS) -I$(KER_SRC) -I$(KER_HEAD) -c $< -o $@ $(CSRCFLAGS)

$(OBJ_DIR)/%.o: $(KER_SRC)/$(ARCHDIR)/%.cpp
    mkdir -p $(@D)
    $(CC) $(CXXFLAGS) -I$(KER_SRC) -I$(KER_HEAD) -c $< -o $@ $(CSRCFLAGS)

$(OBJ_DIR)/%.o: $(COMMON_SRC)/%.c
    mkdir -p $(@D)
    $(CC) $(CFLAGS) -I$(KER_SRC) -I$(KER_HEAD) -c $< -o $@ $(CSRCFLAGS)

#$(OBJ_DIR)/%.o: $(KER_MENU_SRC)/%.c
#   mkdir -p $(@D)
#   $(CC) $(CFLAGS) -I$(KER_SRC) -I$(KER_HEAD) -c $< -o $@ $(CSRCFLAGS)

#$(OBJ_DIR)/%.o: $(KER_MENU_SRC)/%.cpp
#   mkdir -p $(@D)
#   $(CC) $(CXXFLAGS) -I$(KER_SRC) -I$(KER_HEAD) -c $< -o $@ $(CSRCFLAGS)

clean:
    rm -rf $(OBJ_DIR)
    rm $(IMG_NAME).elf
    rm $(IMG_NAME).img

run: build
    qemu-system-arm -m 128 -no-reboot -M raspi4 -serial stdio -kernel kernel.elf

dbg:
    $(GDB) kernel.elf
dbgrun: build gdbinit
    qemu-system-arm -m 128 -no-reboot -M raspi4 -serial stdio -kernel kernel.elf -S -s

.PHONY: gdbinit
gdbinit:
    echo "target remote localhost:1234" > .gdbinit
    echo "break kernel_main" >> .gdbinit

解决方法

所以问题是我已经链接了两次 asm 文件，所以我注释掉了第二个 之前：

OBJECTS = $(patsubst $(KER_SRC)/%.s,$(OBJ_DIR)/%.o,$(ASMSOURCES))
OBJECTS += $(patsubst $(KER_SRC)/%.s,$(ASMSOURCES))

之后：

OBJECTS = $(patsubst $(KER_SRC)/%.s,$(ASMSOURCES))
#OBJECTS += $(patsubst $(KER_SRC)/%.s,$(ASMSOURCES))