main.c.o使用VFP寄存器参数，a.out不使用

编程问答 2023-06-28

问题描述

我有一个main.c正在像这样编译：

arm-none-eabi-gcc -mcpu=cortex-a9 -mfpu=vfpv3 -mfloat-abi=hard -o CMakeFiles/lab1.elf.dir/main.c.o -c main.c

readelf -A main.c.o的输出：

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
  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: small
  Tag_ABI_VFP_args: VFP registers
  Tag_ABI_optimization_goals: Aggressive Debug
  Tag_cpu_unaligned_access: v6
  Tag_MPextension_use: Allowed
  Tag_Virtualization_use: TrustZone

然后我想将此文件与我拥有的其他一些库链接（这些是C ++库，因此我正在使用g ++链接器）。我不断收到错误消息，尽管使用命令行选项启用了可执行文件，但该可执行文件未使用VFP参数：

arm-none-eabi-g++ -mcpu=cortex-a9 -mfpu=vfpv3 -mfloat-abi=hard  CMakeFiles/lab1.elf.dir/main.c.o

这是输出：

（是的，还有很多其他问题，例如缺少库等，但是我试图将其简化为一个简单的示例）。

（此外，这在GCC 6.3.1中也能正常工作，但现在我在9.2.1中进行了尝试，才被打破了）

/usr/lib/gcc/arm-none-eabi/9.2.1/../../../arm-none-eabi/bin/ld: error: CMakeFiles/lab1.elf.dir/main.c.o uses VFP register arguments,a.out does not
/usr/lib/gcc/arm-none-eabi/9.2.1/../../../arm-none-eabi/bin/ld: Failed to merge target specific data of file CMakeFiles/lab1.elf.dir/main.c.o
/usr/lib/gcc/arm-none-eabi/9.2.1/../../../arm-none-eabi/bin/ld: CMakeFiles/lab1.elf.dir/main.c.o: in function `main':
main.c:(.text+0x8): undefined reference to `display_init'
/usr/lib/gcc/arm-none-eabi/9.2.1/../../../arm-none-eabi/bin/ld: main.c:(.text+0x10): undefined reference to `display_fillScreen'
/usr/lib/gcc/arm-none-eabi/9.2.1/../../../arm-none-eabi/bin/ld: main.c:(.text+0x1c): undefined reference to `display_setCursor'
/usr/lib/gcc/arm-none-eabi/9.2.1/../../../arm-none-eabi/bin/ld: main.c:(.text+0x24): undefined reference to `display_setTextColor'
/usr/lib/gcc/arm-none-eabi/9.2.1/../../../arm-none-eabi/bin/ld: main.c:(.text+0x2c): undefined reference to `display_setTextSize'
/usr/lib/gcc/arm-none-eabi/9.2.1/../../../arm-none-eabi/bin/ld: main.c:(.text+0x38): undefined reference to `display_println'
/usr/lib/gcc/arm-none-eabi/9.2.1/../../../arm-none-eabi/bin/ld: /usr/lib/gcc/arm-none-eabi/9.2.1/../../../arm-none-eabi/lib/libc.a(lib_a-exit.o): in function `exit':
/build/newlib-CVVEyx/newlib-3.3.0/build/arm-none-eabi/newlib/libc/stdlib/../../../../../newlib/libc/stdlib/exit.c:64: undefined reference to `_exit'
/usr/lib/gcc/arm-none-eabi/9.2.1/../../../arm-none-eabi/bin/ld: /usr/lib/gcc/arm-none-eabi/9.2.1/../../../arm-none-eabi/lib/libc.a(lib_a-sbrkr.o): in function `_sbrk_r':
/build/newlib-CVVEyx/newlib-3.3.0/build/arm-none-eabi/newlib/libc/reent/../../../../../newlib/libc/reent/sbrkr.c:51: undefined reference to `_sbrk'
/usr/lib/gcc/arm-none-eabi/9.2.1/../../../arm-none-eabi/bin/ld: /usr/lib/gcc/arm-none-eabi/9.2.1/../../../arm-none-eabi/lib/libc.a(lib_a-writer.o): in function `_write_r':
/build/newlib-CVVEyx/newlib-3.3.0/build/arm-none-eabi/newlib/libc/reent/../../../../../newlib/libc/reent/writer.c:49: undefined reference to `_write'
/usr/lib/gcc/arm-none-eabi/9.2.1/../../../arm-none-eabi/bin/ld: /usr/lib/gcc/arm-none-eabi/9.2.1/../../../arm-none-eabi/lib/libc.a(lib_a-closer.o): in function `_close_r':
/build/newlib-CVVEyx/newlib-3.3.0/build/arm-none-eabi/newlib/libc/reent/../../../../../newlib/libc/reent/closer.c:47: undefined reference to `_close'
/usr/lib/gcc/arm-none-eabi/9.2.1/../../../arm-none-eabi/bin/ld: /usr/lib/gcc/arm-none-eabi/9.2.1/../../../arm-none-eabi/lib/libc.a(lib_a-fstatr.o): in function `_fstat_r':
/build/newlib-CVVEyx/newlib-3.3.0/build/arm-none-eabi/newlib/libc/reent/../../../../../newlib/libc/reent/fstatr.c:55: undefined reference to `_fstat'
/usr/lib/gcc/arm-none-eabi/9.2.1/../../../arm-none-eabi/bin/ld: /usr/lib/gcc/arm-none-eabi/9.2.1/../../../arm-none-eabi/lib/libc.a(lib_a-isattyr.o): in function `_isatty_r':
/build/newlib-CVVEyx/newlib-3.3.0/build/arm-none-eabi/newlib/libc/reent/../../../../../newlib/libc/reent/isattyr.c:52: undefined reference to `_isatty'
/usr/lib/gcc/arm-none-eabi/9.2.1/../../../arm-none-eabi/bin/ld: /usr/lib/gcc/arm-none-eabi/9.2.1/../../../arm-none-eabi/lib/libc.a(lib_a-lseekr.o): in function `_lseek_r':
/build/newlib-CVVEyx/newlib-3.3.0/build/arm-none-eabi/newlib/libc/reent/../../../../../newlib/libc/reent/lseekr.c:49: undefined reference to `_lseek'
/usr/lib/gcc/arm-none-eabi/9.2.1/../../../arm-none-eabi/bin/ld: /usr/lib/gcc/arm-none-eabi/9.2.1/../../../arm-none-eabi/lib/libc.a(lib_a-readr.o): in function `_read_r':
/build/newlib-CVVEyx/newlib-3.3.0/build/arm-none-eabi/newlib/libc/reent/../../../../../newlib/libc/reent/readr.c:49: undefined reference to `_read'
/usr/lib/gcc/arm-none-eabi/9.2.1/../../../arm-none-eabi/bin/ld: /usr/lib/gcc/arm-none-eabi/9.2.1/../../../arm-none-eabi/lib/libc.a(lib_a-abort.o): in function `abort':
/build/newlib-CVVEyx/newlib-3.3.0/build/arm-none-eabi/newlib/libc/stdlib/../../../../../newlib/libc/stdlib/abort.c:59: undefined reference to `_exit'
/usr/lib/gcc/arm-none-eabi/9.2.1/../../../arm-none-eabi/bin/ld: /usr/lib/gcc/arm-none-eabi/9.2.1/../../../arm-none-eabi/lib/libc.a(lib_a-signalr.o): in function `_kill_r':
/build/newlib-CVVEyx/newlib-3.3.0/build/arm-none-eabi/newlib/libc/reent/../../../../../newlib/libc/reent/signalr.c:53: undefined reference to `_kill'
/usr/lib/gcc/arm-none-eabi/9.2.1/../../../arm-none-eabi/bin/ld: /usr/lib/gcc/arm-none-eabi/9.2.1/../../../arm-none-eabi/lib/libc.a(lib_a-signalr.o): in function `_getpid_r':
/build/newlib-CVVEyx/newlib-3.3.0/build/arm-none-eabi/newlib/libc/reent/../../../../../newlib/libc/reent/signalr.c:83: undefined reference to `_getpid'
collect2: error: ld returned 1 exit status

解决方法

我认为这与此处讨论的问题类似：Problem cross-compiling trivial example with gcc when using hard float

尽管为链接器指定了-mcpu=cortex-a9 -mfpu=vfpv3 -mfloat-abi=hard选项，但似乎链接了错误的libc版本。

我能够使用-march=armv7-a而不是-mcpu=cortex-a9来解决此问题，如该页面上的评论之一所示。

,

如果未来有人偶然发现这个话题并正在寻找答案：

我必须检查是否为 GCC G++ 和链接器设置了 -mfloat-abi=hard。 但是因为选择了硬件，我必须还检查是否设置了 -mfpu=XXX（这不是出于某种晦涩的原因）

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