当我尝试编译一个简单的示例test.c
int main () {
return 0;
}
使用以下调用针对具有硬浮点ABI的cortex m7目标
arm-none-eabi-gcc -mcpu=cortex-m7 -mfpu=fpv5-d16 -mfloat-abi=hard --specs=nosys.specs test.c
我收到此错误：
/usr/lib/gcc/arm-none-eabi/6.3.1/../../../arm-none-eabi/bin/ld: error: /usr/lib/gcc/arm-none-eabi/6.3.1/../../../arm-none-eabi/lib/crt0.o: Conflicting CPU architectures 13/1
/usr/lib/gcc/arm-none-eabi/6.3.1/../../../arm-none-eabi/bin/ld: failed to merge target specific data of file /usr/lib/gcc/arm-none-eabi/6.3.1/../../../arm-none-eabi/lib/crt0.o
/usr/lib/gcc/arm-none-eabi/6.3.1/../../../arm-none-eabi/bin/ld: error: a.out uses VFP register arguments, /usr/lib/gcc/arm-none-eabi/6.3.1/../../../arm-none-eabi/lib/libc.a(lib_a-atexit.o) does not
[snip]
/usr/lib/gcc/arm-none-eabi/6.3.1/../../../arm-none-eabi/bin/ld: failed to merge target specific data of file /usr/lib/gcc/arm-none-eabi/6.3.1/../../../arm-none-eabi/lib/libnosys.a(_exit.o)
collect2: error: ld returned 1 exit status
所以问题是gcc链接到错误的libc.a。如果我使用参数print-multi-directory，则看来我的arm-none-eabi-gcc版本应该支持以下架构：
$ arm-none-eabi-gcc -mcpu=cortex-m7 -mfpu=fpv5-d16 -mfloat-abi=hard --specs=nosys.specs --print-multi-directory
thumb/v7e-m/fpv5/hard
然后我可以列出libc.a提供的arm-none-eabi-gcc的不同版本：
$ find /usr/lib/arm-none-eabi/ -name libc.a
/usr/lib/arm-none-eabi/newlib/armv7e-m/libc.a
/usr/lib/arm-none-eabi/newlib/armv7e-m/fpu/fpv5-sp-d16/libc.a
/usr/lib/arm-none-eabi/newlib/armv7e-m/fpu/libc.a
/usr/lib/arm-none-eabi/newlib/armv7e-m/fpu/fpv5-d16/libc.a
/usr/lib/arm-none-eabi/newlib/armv7e-m/softfp/fpv5-sp-d16/libc.a
/usr/lib/arm-none-eabi/newlib/armv7e-m/softfp/libc.a
/usr/lib/arm-none-eabi/newlib/armv7e-m/softfp/fpv5-d16/libc.a
/usr/lib/arm-none-eabi/newlib/libc.a
/usr/lib/arm-none-eabi/newlib/armv6-m/libc.a
/usr/lib/arm-none-eabi/newlib/fpu/libc.a
/usr/lib/arm-none-eabi/newlib/thumb/libc.a
/usr/lib/arm-none-eabi/newlib/armv7-m/libc.a
因此，似乎为我想要的体系结构编译了一个libc.a版本，但是gcc并未针对它进行链接。如何获得gcc链接到正确版本的libc.a？
我正在使用gcc-arm-none-eabi软件包为Ubuntu 18.04提供的arm-none-eabi-gcc版本6.3.1。