我有一个正在编译的main.c，如下所示：
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
然后我想将这个文件与我拥有的其他一些库链接起来(这些是C++库，所以我使用g++链接器(。我一直收到一个错误，即可执行文件没有使用VFP参数，尽管有命令行选项可以启用它们：
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，缺少库等还有很多其他问题，但我试图将其简化为一个简单的例子(。
(此外，这在GCC 6.3.1中运行良好，现在我正在9.2.1中尝试，它才被破坏(
/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
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Linker设置了-mfloat-abi=hard。但因为选择了硬件，我不得不也检查是否设置了-mfpu=XXX(这不是因为一些模糊的原因(
我相信这是一个与这里讨论的问题类似的问题：当使用硬浮点时，用gcc交叉编译琐碎的例子的问题
尽管为链接器提供了-mcpu=cortex-a9 -mfpu=vfpv3 -mfloat-abi=hard选项，但似乎链接到了错误的libc版本。
正如该页面上的一条评论所建议的那样，我可以通过使用-march=armv7-a而不是-mcpu=cortex-a9来解决这个问题。