为什么arm-linux-gnueabi-g ++-4.4总是生成“ 7-A”二进制文件？

Question

我正在运行Ubuntu 12：04LTS，并安装了arm-linux-gnueabi C和C
++编译器。编译后的二进制文件无法在我的目标板上运行。看起来，即使我指定了cpu和arch，编译器仍会为错误的CPU构建二进制文件。它代替了atm9tdmi并构建了7-A。

我做错了什么还是应该配置一些东西？谢谢。

~/ArmTest$ arm-linux-gnueabi-g++-4.4 -mcpu=arm9tdmi -march=armv4t -O main.cpp -o CPPTest

~/ArmTest$ readelf -A CPPTest 
Attribute Section: aeabi
File Attributes
  Tag_CPU_name: "7-A"
  Tag_CPU_arch: v7
  Tag_CPU_arch_profile: Application
  Tag_ARM_ISA_use: Yes
  Tag_THUMB_ISA_use: Thumb-2
  Tag_FP_arch: VFPv3-D16
  Tag_ABI_PCS_wchar_t: 4
  Tag_ABI_FP_denormal: Needed
  Tag_ABI_FP_exceptions: Needed
  Tag_ABI_FP_number_model: IEEE 754
  Tag_ABI_align_needed: 8-byte
  Tag_ABI_align_preserved: 8-byte, except leaf SP
  Tag_ABI_enum_size: int
  Tag_ABI_HardFP_use: SP and DP
  Tag_CPU_unaligned_access: v6
  Tag_DIV_use: Not allowed
~/ArmTest$ file CPPTest 
CPPTest: ELF 32-bit LSB executable, ARM, version 1 (SYSV), dynamically linked (uses shared libs), for GNU/Linux 2.6.31, BuildID[sha1]=0xf8e81f7a1bb3ee1200cb3dd1aa5b192ecc6de831, not stripped

 uname -a
Linux Desktop 3.2.0-32-generic-pae #51-Ubuntu SMP Wed Sep 26 21:54:23 UTC 2012 i686 athlon i386 GNU/Linux

:~/ArmTest$ arm-linux-gnueabi-g++-4.4 -v
Using built-in specs.
Target: arm-linux-gnueabi
Configured with: ../src/configure -v --with-pkgversion='Ubuntu/Linaro 4.4.7-1ubuntu2' --with-bugurl=file:///usr/share/doc/gcc-4.4/README.Bugs --enable-languages=c,c++,fortran,objc,obj-c++ --prefix=/usr --program-suffix=-4.4 --enable-shared --enable-linker-build-id --with-system-zlib --libexecdir=/usr/lib --without-included-gettext --enable-threads=posix --with-gxx-include-dir=/usr/arm-linux-gnueabi/include/c++/4.4.7 --libdir=/usr/lib --enable-nls --enable-clocale=gnu --enable-libstdcxx-debug --enable-objc-gc --disable-sjlj-exceptions --with-arch=armv7-a --with-float=softfp --with-fpu=vfpv3-d16 --with-mode=thumb --disable-werror --enable-checking=release --program-prefix=arm-linux-gnueabi- --includedir=/usr/arm-linux-gnueabi/include --build=i686-linux-gnu --host=i686-linux-gnu --target=arm-linux-gnueabi --with-headers=/usr/arm-linux-gnueabi/include --with-libs=/usr/arm-linux-gnueabi/lib
Thread model: posix
gcc version 4.4.7 (Ubuntu/Linaro 4.4.7-1ubuntu2)

:~/ArmTest$ cat main.cpp
#include<iostream>

using namespace std;

int main(){
   cout<<"Hello World"<<endl;
return 0;
}

Answer 1

您的编译器支持armv4t，问题是您的链接器必须将您的目标文件与libc，crt.o等其他文件链接才能创建可执行文件。但是，在您的工具链中，所有这些文件都已针对7-A进行了编译，因此，可执行文件最终也将成为一个文件。这是ubuntu
cross工具链的问题，默认情况下它们是armv7a。

如果 仅编译 源文件，则会看到编译器输出正确的目标文件类型。

$ arm-linux-gnueabi-g ++-4.4 -mcpu = arm9tdmi -march = armv4t -O -c
main.cpp -o CPPTest

$ readelf -A CPPTest
Attribute Section: aeabi
File Attributes
  Tag_CPU_name: "ARM9TDMI"
  Tag_CPU_arch: v4T
  Tag_ARM_ISA_use: Yes
  Tag_THUMB_ISA_use: Thumb-1
  Tag_FP_arch: VFPv3-D16
  Tag_ABI_PCS_wchar_t: 4
  Tag_ABI_FP_denormal: Needed
  Tag_ABI_FP_exceptions: Needed
  Tag_ABI_FP_number_model: IEEE 754
  Tag_ABI_align_needed: 8-byte
  Tag_ABI_align_preserved: 8-byte, except leaf SP
  Tag_ABI_enum_size: int
  Tag_ABI_HardFP_use: SP and DP
  Tag_ABI_optimization_goals: Prefer Speed
  Tag_DIV_use: Not allowed

因此，工具链不仅仅是编译器，它的每个组件都需要配合使用。