Question

我有一个包含链接程序脚本的STM32项目，该链接程序旨在使用“ .firmware_header”部分封闭图像的结尾。想法是此标头包含图像的crc，并且在此之后应该没有内容。但是，当我这样做

arm-none-eabi-objcopy firmware.elf -O binary firmware.bin

在最后一节之后有一些数据，出于某种原因引导映像是必需的。如果我将此谜题块归零，则映像无法启动。第一个问题是，从我看到的elf部分来看，.firmware_header之后应该没有任何部分，数据来自何处？第二个问题是，为什么引导时需要这些数据？我的链接器脚本，readelf输出和神秘数据的屏幕截图如下。

ENTRY(Reset_Handler)

MEMORY
{
  FLASH (RX) : ORIGIN = 0x08020000, LENGTH = 896K
  SRAM (RWX) : ORIGIN = 0x20000000, LENGTH = 512K
  BKPSRAM (RW) : ORIGIN = 0x40024000, LENGTH = 4K
}

_estack = 0x20080000;

SECTIONS
{
  .isr_vector :
  {
    . = ALIGN(4);
    _isr_vector = .;
    KEEP(*(.isr_vector))
    . = ALIGN(4);
  } > FLASH

  .firmware_header_vector :
  {
    . = ALIGN(4);
    KEEP(*(.firmware_header_vector))
    . = ALIGN(4);
  } > FLASH

  .text :
  {
    . = ALIGN(4);
    _stext = .;
    *(.Reset_Handler)
    *(.text)
    *(.text*)
    *(.rodata)
    *(.rodata*)
    *(.glue_7)
    *(.glue_7t)
    KEEP(*(.init))
    KEEP(*(.fini))
    . = ALIGN(4);
    _etext = .;

  } > FLASH

  .ARM.extab :
  {
    . = ALIGN(4);
    *(.ARM.extab)
    *(.gnu.linkonce.armextab.*)
    . = ALIGN(4);
  } > FLASH

  .exidx :
  {
    . = ALIGN(4);
    PROVIDE(__exidx_start = .);
    *(.ARM.exidx*)
    . = ALIGN(4);
    PROVIDE(__exidx_end = .);
  } > FLASH

  .preinit_array :
  {
    PROVIDE(__preinit_array_start = .);
    KEEP(*(.preinit_array*))
    PROVIDE(__preinit_array_end = .);
  } > FLASH

  .init_array :
  {
    PROVIDE(__init_array_start = .);
    KEEP(*(SORT(.init_array.*)))
    KEEP(*(.init_array*))
    PROVIDE(__init_array_end = .);
  } > FLASH

  .fini_array :
  {
    PROVIDE(__fini_array_start = .);
    KEEP(*(.fini_array*))
    KEEP(*(SORT(.fini_array.*)))
    PROVIDE(__fini_array_end = .);
  } > FLASH

  .firmware_header :
  {
    . = ALIGN(4);
    KEEP(*(.firmware_header))
    . = ALIGN(4);
  } > FLASH

  . = ALIGN(4);
  _sidata = .;

  .data : AT(_sidata)
  {
    . = ALIGN(4);
    _sdata = .;

    PROVIDE(__data_start__ = _sdata);
    *(.data)
    *(.data*)
    . = ALIGN(4);
    _edata = .;

    PROVIDE(__data_end__ = _edata);
  } > SRAM

  .bss :
  {
    . = ALIGN(4);
    _sbss = .;

    PROVIDE(__bss_start__ = _sbss);
    *(.bss)
    *(.bss*)
    *(COMMON)
    . = ALIGN(4);
    _ebss = .;

    PROVIDE(__bss_end__ = _ebss);
  } > SRAM

  PROVIDE(end = .);

  .heap (NOLOAD) :
  {
    . = ALIGN(4);
    PROVIDE(__heap_start__ = .);
    KEEP(*(.heap))
    . = ALIGN(4);
    PROVIDE(__heap_end__ = .);
  } > SRAM

  .reserved_for_stack (NOLOAD) :
  {
    . = ALIGN(4);
    PROVIDE(__reserved_for_stack_start__ = .);
    KEEP(*(.reserved_for_stack))
    . = ALIGN(4);
    PROVIDE(__reserved_for_stack_end__ = .);
  } > SRAM

  .battery_backed_sram (NOLOAD) :
  {
    . = ALIGN(4);
    KEEP(*(.battery_backed_sram))
    . = ALIGN(4);
  } > BKPSRAM

  /DISCARD/ :
  {
    *(.ARM.attributes)
  }
}

arm-none-eabi-readelf -a ./fw.elf：

ELF Header:
  Magic:   7f 45 4c 46 01 01 01 00 00 00 00 00 00 00 00 00 
  Class:                             ELF32
  Data:                              2's complement, little endian
  Version:                           1 (current)
  OS/ABI:                            UNIX - System V
  ABI Version:                       0
  Type:                              EXEC (Executable file)
  Machine:                           ARM
  Version:                           0x1
  Entry point address:               0x8027c11
  Start of program headers:          52 (bytes into file)
  Start of section headers:          339928 (bytes into file)
  Flags:                             0x5000400, Version5 EABI, hard-float ABI
  Size of this header:               52 (bytes)
  Size of program headers:           32 (bytes)
  Number of program headers:         3
  Size of section headers:           40 (bytes)
  Number of section headers:         25
  Section header string table index: 24

Section Headers:
  [Nr] Name              Type            Addr     Off    Size   ES Flg Lk Inf Al
  [ 0]                   NULL            00000000 000000 000000 00      0   0  0
  [ 1] .isr_vector       PROGBITS        08020000 010000 0001f8 00  WA  0   0  4
  [ 2] .firmware_header_ PROGBITS        080201f8 0101f8 000004 00  WA  0   0  4
  [ 3] .text             PROGBITS        08020200 010200 021b44 00  AX  0   0 64
  [ 4] .ARM.extab        PROGBITS        08041d44 043a68 000000 00   W  0   0  1
  [ 5] .exidx            ARM_EXIDX       08041d44 031d44 000008 00  AL  3   0  4
  [ 6] .init_array       INIT_ARRAY      08041d4c 031d4c 000008 04  WA  0   0  4
  [ 7] .fini_array       FINI_ARRAY      08041d54 031d54 000004 04  WA  0   0  4
  [ 8] .firmware_header  PROGBITS        08041d58 031d58 000008 00  WA  0   0  4
  [ 9] .data             PROGBITS        20000000 040000 0009c8 00  WA  0   0  8
  [10] .RxDecripSection  PROGBITS        200009c8 0409c8 000080 00  WA  0   0  4
  [11] .RxarraySection   PROGBITS        20000a48 040a48 0017d0 00  WA  0   0  4
  [12] .TxDescripSection PROGBITS        20002218 042218 000080 00  WA  0   0  4
  [13] .TxarraySection   PROGBITS        20002298 042298 0017d0 00  WA  0   0  4
  [14] .bss              NOBITS          20003a68 043a68 045da4 00  WA  0   0  4
  [15] .heap             PROGBITS        2004980c 043a68 000000 00   W  0   0  1
  [16] .reserved_for_sta PROGBITS        2004980c 043a68 000000 00   W  0   0  1
  [17] .battery_backed_s NOBITS          40024000 044000 00000c 00  WA  0   0  4
  [18] .comment          PROGBITS        00000000 043a68 000075 01  MS  0   0  1
  [19] .debug_frame      PROGBITS        00000000 043ae0 00144c 00      0   0  4
  [20] .stab             PROGBITS        00000000 044f2c 000084 0c     21   0  4
  [21] .stabstr          STRTAB          00000000 044fb0 000117 00      0   0  1
  [22] .symtab           SYMTAB          00000000 0450c8 009b30 10     23 1790  4
  [23] .strtab           STRTAB          00000000 04ebf8 0042bb 00      0   0  1
  [24] .shstrtab         STRTAB          00000000 052eb3 000122 00      0   0  1
Key to Flags:
  W (write), A (alloc), X (execute), M (merge), S (strings), I (info),
  L (link order), O (extra OS processing required), G (group), T (TLS),
  C (compressed), x (unknown), o (OS specific), E (exclude),
  y (purecode), p (processor specific)

There are no section groups in this file.

Program Headers:
  Type           Offset   VirtAddr   PhysAddr   FileSiz MemSiz  Flg Align
  LOAD           0x010000 0x08020000 0x08020000 0x21d60 0x21d60 RWE 0x10000
  LOAD           0x040000 0x20000000 0x08041d60 0x03a68 0x4980c RW  0x10000
  LOAD           0x044000 0x40024000 0x40024000 0x00000 0x0000c RW  0x10000

Answer 1

原来，这是.data节的定义存在的问题。在.firmware_header之后加载。有趣的是，在readefl等输出中并没有更清楚地说明这一点。解决了！

额外的数据在objcopy之后以二进制形式显示...它来自哪里？

1 个答案: