在Linux手机上执行./a.out，报告找不到a.out的错误分析

在使用了ext3/xfs两种格式格式化TF卡后，复制到TF卡上的程序文件竟然不能执行，sh报告找不到文件。
-sh: ./a.out: not found

而把echo从/bin下复制到T卡上，这个程序却是可以执行的，说明T卡没有问题，分区也没有问题。只是可执行文件格式的问题。

使用file以及readelf分别对照可以执行以及不能执行的二进制的header区。

发现他们的ELF Version不一样：

xiewei@xiewei-desktop disk $ file echo.ok 
echo.ok    : ELF 32-bit LSB executable, ARM, version 1, dynamically linked (uses shared libs), stripped

xiewei@xiewei-desktop disk $ file echo.not.ok  
echo.not.ok: ELF 32-bit LSB executable, ARM, version 1 (SYSV), dynamically linked (uses shared libs), stripped

xiewei@xiewei-desktop disk $ readelf -h echo.ok 
ELF Header:
  Magic:   7f 45 4c 46 01 01 01 61 00 00 00 00 00 00 00 00 
  Class:                             ELF32
  Data:                              2's complement, little endian
  Version:                           1 (current)
  OS/ABI:                            ARM
  ABI Version:                       0
  Type:                              EXEC (Executable file)
  Machine:                           ARM
  Version:                           0x1
  Entry point address:               0xcdfc
  Start of program headers:          52 (bytes into file)
  Start of section headers:          563772 (bytes into file)
  Flags:                             0x6, has entry point, GNU EABI, interworking enabled
  Size of this header:               52 (bytes)
  Size of program headers:           32 (bytes)
  Number of program headers:         5
  Size of section headers:           40 (bytes)
  Number of section headers:         23
  Section header string table index: 22

xiewei@xiewei-desktop disk $ readelf -h echo.not.ok  
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:               0xf1a0
  Start of program headers:          52 (bytes into file)
  Start of section headers:          546060 (bytes into file)
  Flags:                             0x5000002, has entry point, Version5 EABI
  Size of this header:               52 (bytes)
  Size of program headers:           32 (bytes)
  Number of program headers:         7
  Size of section headers:           40 (bytes)
  Number of section headers:         26
  Section header string table index: 25

 

后来仔细考虑了一下，肯定是由于kernel/rootfs/echo使用的arm交叉编译工具链不同导致的。在网上查了一下，确认这种分析是正确的。

这个困扰了我有半年之久的问题，终于搞定了。