为啥链接器无法识别我的链接器脚本中定义的入口点

Posted 2023-02-19

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【中文标题】为啥链接器无法识别我的链接器脚本中定义的入口点【英文标题】：Why is the linker not recognizing the entry point defined in my linker script为什么链接器无法识别我的链接器脚本中定义的入口点 【发布时间】：2021-09-15 22:17:28 【问题描述】：

我正在尝试与目标交叉编译为 STM32F030F4P6，我设置了包含我的向量表的 startup.c 和 startup.h 文件。我已经编写了 2 个链接器脚本，一个用于内存，另一个用于部分。根据数据表，STM32f030F4 在系统复位后将 PC 设置为 0x00000000，并且向量表必须存在于该地址，因为递增后它必须在 0x00000004 处执行 Reset_Handler（系统复位）并初始化系统。

当我链接此链接时，链接器会给我以下警告

" warning: cannot find entry symbol _start; defaulting to 00008000"

Question
Why is the linker not detecting my Entry point defined by ENTRY(Reset_Handler)?

请找到我的源文件、头文件和链接器脚本。

脚本.ld 这包含部分

ENTRY(Reset_Handler)


SECTIONS

  .text :
  
    *(.isr_vector)
    *(.text)
    *(.rodata)
    _etext= .;
  > FLASH 

  .data :
  
    _sdata = .;
    *(.data)
    _edata = .;
  > SRAM AT> FLASH

  .bss :
  
    _sbss = .;
    *(.bss)
    _ebss = .;
  > SRAM

内存.ld 该文件包含内存定义。注意-STM32F030F4P 只有 FLASH & RAM，所以 EXTMEMBx 定义为 0x00000000 of LENGTH 4K

MEMORY

  FLASH     (rx)    :   ORIGIN = 0x08000000,   LENGTH = 16K
  RAM       (xrw)   :   ORIGIN = 0x20000000,  LENGTH = 4K
  EXTMEMB0  (rx)    :   ORIGIN = 0x00000000, LENGTH = 0K
  EXTMEMB1  (rx)    :   ORIGIN = 0x00000000, LENGTH = 0K
  EXTMEMB2  (rx)    :   ORIGIN = 0x00000000, LENGTH = 0K
  EXTMEMB3  (rx)    :   ORIGIN = 0x00000000, LENGTH = 0K

启动.h 包含向量定义

#include "stdint.h"

/* Calculate the vlaue of stack. */ 
/* Full- descending stack in cortex-m0 means stack must be placed at the end of SRAM. */
/* Stack pointer is decremented as a a PUSH operation is executed */

#define SRAM_Start  0x20000000U
#define SRAM_End    SRAM_Start+4096U
#define Stack_Start SRAM_End


/* Vector Definitions */
void Reset_Handler(void);
void NMI_Handler(void)          __attribute__((weak, alias("Default_Handler")));
void HardFault_Handler(void)    __attribute__((weak, alias("Default_Handler")));
void SVCall_Handler(void)       __attribute__((weak, alias("Default_Handler")));
void PendSV_Handler(void)       __attribute__((weak, alias("Default_Handler")));
void SysTick_Handler(void)      __attribute__((weak, alias("Default_Handler")));

void IRQ0_Handler(void)         __attribute__((weak, alias("Default_Handler")));
void IRQ1_Handler(void)         __attribute__((weak, alias("Default_Handler")));
void IRQ2_Handler(void)         __attribute__((weak, alias("Default_Handler")));
void IRQ3_Handler(void)         __attribute__((weak, alias("Default_Handler")));
void IRQ4_Handler(void)         __attribute__((weak, alias("Default_Handler")));
void IRQ5_Handler(void)         __attribute__((weak, alias("Default_Handler")));
void IRQ6_Handler(void)         __attribute__((weak, alias("Default_Handler")));
void IRQ7_Handler(void)         __attribute__((weak, alias("Default_Handler")));
void IRQ8_Handler(void)         __attribute__((weak, alias("Default_Handler")));
void IRQ9_Handler(void)         __attribute__((weak, alias("Default_Handler")));
void IRQ10_Handler(void)         __attribute__((weak, alias("Default_Handler")));
void IRQ11_Handler(void)         __attribute__((weak, alias("Default_Handler")));
void IRQ12_Handler(void)         __attribute__((weak, alias("Default_Handler")));
void IRQ13_Handler(void)         __attribute__((weak, alias("Default_Handler")));
void IRQ14_Handler(void)         __attribute__((weak, alias("Default_Handler")));
void IRQ15_Handler(void)         __attribute__((weak, alias("Default_Handler")));
void IRQ16_Handler(void)         __attribute__((weak, alias("Default_Handler")));
void IRQ17_Handler(void)         __attribute__((weak, alias("Default_Handler")));
void IRQ18_Handler(void)         __attribute__((weak, alias("Default_Handler")));
void IRQ19_Handler(void)         __attribute__((weak, alias("Default_Handler")));
void IRQ20_Handler(void)         __attribute__((weak, alias("Default_Handler")));
void IRQ21_Handler(void)         __attribute__((weak, alias("Default_Handler")));
void IRQ22_Handler(void)         __attribute__((weak, alias("Default_Handler")));
void IRQ23_Handler(void)         __attribute__((weak, alias("Default_Handler")));
void IRQ24_Handler(void)         __attribute__((weak, alias("Default_Handler")));
void IRQ25_Handler(void)         __attribute__((weak, alias("Default_Handler")));
void IRQ26_Handler(void)         __attribute__((weak, alias("Default_Handler")));
void IRQ27_Handler(void)         __attribute__((weak, alias("Default_Handler")));
void IRQ28_Handler(void)         __attribute__((weak, alias("Default_Handler")));
void IRQ29_Handler(void)         __attribute__((weak, alias("Default_Handler")));
void IRQ30_Handler(void)         __attribute__((weak, alias("Default_Handler")));
void IRQ31_Handler(void)         __attribute__((weak, alias("Default_Handler")));

& 最后启动.c

//Set initial SP value
// PC increments to reset handler
// branch to main

#include "startup.h"



// __attribute__((weak, alias("")))

/* Vector Table */
/* Subsequent to a system RESET PC is set to 0x00000000 */
/* Vector Table must be present at 0x00000000 use __atribute__((section("section_name"))) to place vector table at "section_name" */
/* Use arm-none-eabi-objdump -h/-S to verify if "section_name" is generated for vector table */
/* Value of SP is the first item in the vector table & henceforth msp is loaded */
/* Second value of vector table is RESET HANDLER, */
/* Core Systems must be initialized here such as CLOCK, etc.*/
/* it is from RESET HANDLER the program flow is branched to user application */

uint32_t vector[] __attribute__((section(".isr_vector"))) = 
    Stack_Start,
    (uint32_t)&Reset_Handler,
    (uint32_t)&NMI_Handler,
    (uint32_t)&HardFault_Handler,
    (uint32_t)0x00000000,
    (uint32_t)0x00000000,
    (uint32_t)0x00000000,
    (uint32_t)0x00000000,
    (uint32_t)0x00000000,
    (uint32_t)0x00000000,
    (uint32_t)0x00000000,
    (uint32_t)&SVCall_Handler,
    (uint32_t)0x00000000,
    (uint32_t)0x00000000,
    (uint32_t)&PendSV_Handler,
    (uint32_t)&SysTick_Handler,
    (uint32_t)&IRQ0_Handler,
    (uint32_t)&IRQ1_Handler,
    (uint32_t)&IRQ2_Handler,
    (uint32_t)&IRQ3_Handler,
    (uint32_t)&IRQ4_Handler,
    (uint32_t)&IRQ5_Handler,
    (uint32_t)&IRQ6_Handler,
    (uint32_t)&IRQ7_Handler,
    (uint32_t)&IRQ8_Handler,
    (uint32_t)&IRQ9_Handler,
    (uint32_t)&IRQ10_Handler,
    (uint32_t)&IRQ11_Handler,
    (uint32_t)&IRQ12_Handler,
    (uint32_t)&IRQ13_Handler,
    (uint32_t)&IRQ14_Handler,
    (uint32_t)&IRQ15_Handler,
    (uint32_t)&IRQ16_Handler,
    (uint32_t)&IRQ17_Handler,
    (uint32_t)&IRQ18_Handler,
    (uint32_t)&IRQ19_Handler,
    (uint32_t)&IRQ20_Handler,
    (uint32_t)&IRQ21_Handler,
    (uint32_t)&IRQ22_Handler,
    (uint32_t)&IRQ23_Handler,
    (uint32_t)&IRQ24_Handler,
    (uint32_t)&IRQ25_Handler,
    (uint32_t)&IRQ26_Handler,
    (uint32_t)&IRQ27_Handler,
    (uint32_t)&IRQ28_Handler,
    (uint32_t)&IRQ29_Handler,
    (uint32_t)&IRQ30_Handler,
    (uint32_t)&IRQ31_Handler,
;

/*Function defenition of reset handler*/
/* it is from RESET HANDLER the program flow is branched to user application */

void Reset_Handler(void)

    //  copy .data section
    //  init .bss/SRAM to 0
    //  init clocks etc..
    //  call the application procedure


void Default_Handler(void)

    for(;;)
    
        
    
    //  Just loop as completion of this procedure will give other faults

我的工具链文件 arm-none-eabi.camke

MESSAGE("Running : arm-none-eabi.cmake")

    SET(CMAKE_SYSTEM_PROCESSOR  arm)
    SET(CMAKE_SYSTEM_NAME       Generic)

    SET(CMAKE_C_COMPILER_WORKS  TRUE)
    SET(CMAKE_CXX_COMPILER_WORKS  TRUE)

    SET(CMAKE_TRY_COMPILE_TARGTE_TYPE   STATIC_LIBRARY)

    SET(TARGET      STM32F030x4)
    SET(ARCH        armv6-m)
    SET(CPU         cortex-m0)
    SET(ARM_ISA     mthumb)

    SET(CMAKE_C_COMPILER    arm-none-eabi-gcc)
    SET(CMAKE_CXX_COMPILER  arm-none-eabi-g++)
    SET(CMAKE_ASM_COMPILER  arm-none-eabi-g++)
    SET(CMAKE_SIZE          arm-none-eabi-size)
    SET(CMAKE_OBJDUMP       arm-none-eabi-objdump)
    SET(CMAKE_OBJCOPY       arm-none-eabi-objcopy)

    SET(OPTIMISATION Og)
    SET(DEBUG "ggdb")

    SET(CMAKE_COMMON_FLAGS  "-march=$ARCH -mcpu=$CPU -$ARM_ISA -D$TARGET -$OPTIMISATION -$DEBUG -Wall -Wextra -ffunction-sections -fdata-sections  -ffreestanding -fno-builtin -nostdlib")
    SET(CMAKE_ASM_FLAGS     "$CMAKE_COMMON_FLAGS")
    SET(CMAKE_C_FLAGS       "$CMAKE_COMMON_FLAGS ")
    SET(CMAKE_CXX_FLAGS     "$CMAKE_COMMON_FLAGS -fno-rtti -fno-exceptions -Wno-volatile -std=c++1z")
    SET(CMAKE_EXE_LINKER_FLAGS  "$CMAKE_COMMON_FLAGS -nostartfiles -Wl,-Map,\"$TARGET.map\" -nostartfiles -nolibc --specs=nosys.specs")

    message("CMAKE_C_FLAGS = "          $CMAKE_C_FLAGS)
    message("CMAKE_CXX_FLAGS = "        $CMAKE_CXX_FLAGS)
    message("CMAKE_EXE_LINKER_FLAGS = " $CMAKE_EXE_LINKER_FLAGS)

CMakeLists.txt

CMAKE_MINIMUM_REQUIRED(VERSION 3.20)

INCLUDE("CMake/arm-none-eabi.cmake")

SET(CMAKE_C_STANDARD    11)
SET(CMAKE_CXX_STANDARD  17)


PROJECT(BLINKY VERSION 1.0.1 DESCRIPTION "Blinky Example")
MESSAGE("Building " $PROJECT_NAME)

FILE(GLOB_RECURSE
    LDSCRIPTS
    "ldscripts/*.ld"
)

FOREACH(file $LDSCRIPTS)
    SET(CMAKE_LINKER_FLAGS "$CAMKE_LINKER_FLAGS -T \"$file\" ")
    MESSAGE("Linker is Running " $CMAKE_LINKER_FLAGS)
ENDFOREACH()



#Setup project headers
INCLUDE_DIRECTORIES(
    "Core/"
    "Drivers/"
)

#Setup porject sources
FILE(GLOB_RECURSE
    APPLICATION_SOURCE
    "Application/*.c"
    "Application/*.cpp"
    "Application/*.s"
    "Core/*.c"
    "Core/*cpp"
    "Core/*.s"
    "Drivers/*.c"
    "Drivers/*.cpp"
    "Drivers/*.s"
)


MESSAGE("CMake build directory" $CMAKE_BINARY_DIR)

ADD_EXECUTABLE($TARGET.elf $APPLICATION_SOURCE)

#ADD_CUSTOM_TARGET($TARGET.bin ALL DEPENDS $TARGET.elf COMMAND $CMAKE_OBJCOPY -O binary $TARGET.elf $TARGET.bin)
#ADD_CUSTOM_TARGET($TARGET.hex ALL DEPENDS $TARGET.elf COMMAND $CMAKE_OBJCOPY -O ihex $TARGET.elf $TARGET.hex)

ADD_CUSTOM_COMMAND(OUTPUT $TARGET.bin DEPENDS $TARGET.elf COMMAND $CMAKE_OBJCOPY -O binary $TARGET.elf $TARGET.bin)
ADD_CUSTOM_COMMAND(OUTPUT $TARGET.hex DEPENDS $TARGET.elf COMMAND $CMAKE_OBJCOPY -O ihex $TARGET.elf $TARGET.hex)
ADD_CUSTOM_TARGET($TARGET_bin DEPENDS $TARGET.bin)
ADD_CUSTOM_TARGET($TARGET_hex DEPENDS $TARGET.hex)

ADD_CUSTOM_TARGET(SIZE ALL $CMAKE_SIZE $TARGET.elf DEPENDS $TARGET.elf)

我知道这绝对不是编写启动文件的最佳方式。但重点是让它运行并改进以编写启动文件。

【问题讨论】：

你能提供你的 Makefile 吗？看起来您缺少标志--specs=nosys.specs --specs=nano.specs 提供了包含所有标志的工具链文件，我尝试使用以下标志 -nostartfiles -nolibc --specs=nosys.specs --specs=nano.specs -nostdlib 构建，它仍然不起作用。请提供一个演示问题的最小示例（命令行优先于 makefile）已经分享了 toolcahin faile 但这里是来自 ninja 构建文件的标志。 c FLAGS = -march=armv6-m -mcpu=cortex-m0 -mthumb -DSTM32F030x4 -Og -ggdb -Wall -Wextra -ffunction-sections -fdata-sections -ffreestanding -fno-builtin -nostdlib -fno-rtti -fno-异常 -Wno-volatile -std=c++1z -g LINK_FLAGS = -march=armv6-m -mcpu=cortex-m0 -mthumb -DSTM32F030x4 -Og -ggdb -Wall -Wextra -ffunction-sections -fdata-sections -ffreestanding -fno-builtin -nostdlib -nostartfiles -Wl,-Map,"STM32F030x4.map" -nostartfiles -nolibc --specs=nosys.specs --specs=nano.specs -nostdlib 向链接器请求地图文件。 Reset_Handler 列出了吗？是否列出了 _Reset_Handler（带有前导下划线）？ 【参考方案1】：

_start 是 Newlib C 库的一部分。您是否在链接器命令行上提供了它？

【讨论】：

我已经分享了我的链接器标志，请帮助我。我怎么能不给这些标志

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