我不能用 arm-none-eabi-gcc 编译

Question

我正在尝试使用arm-none-eabi-gcc 编译代码，但出现以下错误。有人可以帮助我或向我解释可能的原因吗？

谢谢！

/usr/lib/gcc/arm-none-eabi/4.9.3/../../../arm-none-eabi/lib/libc.a(lib_a-exit.o): In function `exit':
/build/newlib-5zwpxE/newlib-2.2.0+git20150830.5a3d536/build/arm-none-eabi/newlib/libc/stdlib/../../../../../newlib/libc/stdlib/exit.c:70: undefined reference to `_exit'
/usr/lib/gcc/arm-none-eabi/4.9.3/../../../arm-none-eabi/lib/libc.a(lib_a-fstatr.o): In function `_fstat_r':
/build/newlib-5zwpxE/newlib-2.2.0+git20150830.5a3d536/build/arm-none-eabi/newlib/libc/reent/../../../../../newlib/libc/reent/fstatr.c:62: undefined reference to `_fstat'
/usr/lib/gcc/arm-none-eabi/4.9.3/../../../arm-none-eabi/lib/libc.a(lib_a-openr.o): In function `_open_r':
/build/newlib-5zwpxE/newlib-2.2.0+git20150830.5a3d536/build/arm-none-eabi/newlib/libc/reent/../../../../../newlib/libc/reent/openr.c:59: undefined reference to `_open'
/usr/lib/gcc/arm-none-eabi/4.9.3/../../../arm-none-eabi/lib/libc.a(lib_a-sbrkr.o): In function `_sbrk_r':
/build/newlib-5zwpxE/newlib-2.2.0+git20150830.5a3d536/build/arm-none-eabi/newlib/libc/reent/../../../../../newlib/libc/reent/sbrkr.c:58: undefined reference to `_sbrk'
/usr/lib/gcc/arm-none-eabi/4.9.3/../../../arm-none-eabi/lib/libc.a(lib_a-writer.o): In function `_write_r':
/build/newlib-5zwpxE/newlib-2.2.0+git20150830.5a3d536/build/arm-none-eabi/newlib/libc/reent/../../../../../newlib/libc/reent/writer.c:58: undefined reference to `_write'
/usr/lib/gcc/arm-none-eabi/4.9.3/../../../arm-none-eabi/lib/libc.a(lib_a-closer.o): In function `_close_r':
/build/newlib-5zwpxE/newlib-2.2.0+git20150830.5a3d536/build/arm-none-eabi/newlib/libc/reent/../../../../../newlib/libc/reent/closer.c:53: undefined reference to `_close'
/usr/lib/gcc/arm-none-eabi/4.9.3/../../../arm-none-eabi/lib/libc.a(lib_a-isattyr.o): In function `_isatty_r':
/build/newlib-5zwpxE/newlib-2.2.0+git20150830.5a3d536/build/arm-none-eabi/newlib/libc/reent/../../../../../newlib/libc/reent/isattyr.c:58: undefined reference to `_isatty'
/usr/lib/gcc/arm-none-eabi/4.9.3/../../../arm-none-eabi/lib/libc.a(lib_a-lseekr.o): In function `_lseek_r':
/build/newlib-5zwpxE/newlib-2.2.0+git20150830.5a3d536/build/arm-none-eabi/newlib/libc/reent/../../../../../newlib/libc/reent/lseekr.c:58: undefined reference to `_lseek'
/usr/lib/gcc/arm-none-eabi/4.9.3/../../../arm-none-eabi/lib/libc.a(lib_a-readr.o): In function `_read_r':
/build/newlib-5zwpxE/newlib-2.2.0+git20150830.5a3d536/build/arm-none-eabi/newlib/libc/reent/../../../../../newlib/libc/reent/readr.c:58: undefined reference to `_read'

Answer 1

因为您正在为裸机目标编译，newlib 默认情况下不提供仅在具有控制台和硬盘驱动器的系统上才有意义的功能的实现，基本上是系统调用，例如@987654324 @/write/open/close/...

如果您不需要这些函数，使用 --specs=nosys.specs 选项将使您的应用程序链接到默认的、基本上是空的实现，调用时将返回错误代码：

/opt/arm/9/gcc-arm-9.2-2019.12-x86_64-arm-none-eabi/bin/arm-none-eabi-gcc -o hello hello.c
/opt/arm/9/gcc-arm-9.2-2019.12-x86_64-arm-none-eabi/bin/../lib/gcc/arm-none-eabi/9.2.1/../../../../arm-none-eabi/bin/ld: /opt/arm/9/gcc-arm-9.2-2019.12-x86_64-arm-none-eabi/bin/../lib/gcc/arm-none-eabi/9.2.1/../../../../arm-none-eabi/lib/libc.a(lib_a-exit.o): in function `exit':
/tmp/dgboter/bbs/rhev-vm10--rhe6x86_64/buildbot/rhe6x86_64--arm-none-eabi/build/src/newlib-cygwin/newlib/libc/stdlib/exit.c:64: undefined reference to `_exit'
/opt/arm/9/gcc-arm-9.2-2019.12-x86_64-arm-none-eabi/bin/../lib/gcc/arm-none-eabi/9.2.1/../../../../arm-none-eabi/bin/ld: /opt/arm/9/gcc-arm-9.2-2019.12-x86_64-arm-none-eabi/bin/../lib/gcc/arm-none-eabi/9.2.1/../../../../arm-none-eabi/lib/libc.a(lib_a-sbrkr.o): in function `_sbrk_r':
/tmp/dgboter/bbs/rhev-vm10--rhe6x86_64/buildbot/rhe6x86_64--arm-none-eabi/build/src/newlib-cygwin/newlib/libc/reent/sbrkr.c:51: undefined reference to `_sbrk'
/opt/arm/9/gcc-arm-9.2-2019.12-x86_64-arm-none-eabi/bin/../lib/gcc/arm-none-eabi/9.2.1/../../../../arm-none-eabi/bin/ld: /opt/arm/9/gcc-arm-9.2-2019.12-x86_64-arm-none-eabi/bin/../lib/gcc/arm-none-eabi/9.2.1/../../../../arm-none-eabi/lib/libc.a(lib_a-writer.o): in function `_write_r':
/tmp/dgboter/bbs/rhev-vm10--rhe6x86_64/buildbot/rhe6x86_64--arm-none-eabi/build/src/newlib-cygwin/newlib/libc/reent/writer.c:49: undefined reference to `_write'
/opt/arm/9/gcc-arm-9.2-2019.12-x86_64-arm-none-eabi/bin/../lib/gcc/arm-none-eabi/9.2.1/../../../../arm-none-eabi/bin/ld: /opt/arm/9/gcc-arm-9.2-2019.12-x86_64-arm-none-eabi/bin/../lib/gcc/arm-none-eabi/9.2.1/../../../../arm-none-eabi/lib/libc.a(lib_a-closer.o): in function `_close_r':
/tmp/dgboter/bbs/rhev-vm10--rhe6x86_64/buildbot/rhe6x86_64--arm-none-eabi/build/src/newlib-cygwin/newlib/libc/reent/closer.c:47: undefined reference to `_close'
/opt/arm/9/gcc-arm-9.2-2019.12-x86_64-arm-none-eabi/bin/../lib/gcc/arm-none-eabi/9.2.1/../../../../arm-none-eabi/bin/ld: /opt/arm/9/gcc-arm-9.2-2019.12-x86_64-arm-none-eabi/bin/../lib/gcc/arm-none-eabi/9.2.1/../../../../arm-none-eabi/lib/libc.a(lib_a-lseekr.o): in function `_lseek_r':
/tmp/dgboter/bbs/rhev-vm10--rhe6x86_64/buildbot/rhe6x86_64--arm-none-eabi/build/src/newlib-cygwin/newlib/libc/reent/lseekr.c:49: undefined reference to `_lseek'
/opt/arm/9/gcc-arm-9.2-2019.12-x86_64-arm-none-eabi/bin/../lib/gcc/arm-none-eabi/9.2.1/../../../../arm-none-eabi/bin/ld: /opt/arm/9/gcc-arm-9.2-2019.12-x86_64-arm-none-eabi/bin/../lib/gcc/arm-none-eabi/9.2.1/../../../../arm-none-eabi/lib/libc.a(lib_a-readr.o): in function `_read_r':
/tmp/dgboter/bbs/rhev-vm10--rhe6x86_64/buildbot/rhe6x86_64--arm-none-eabi/build/src/newlib-cygwin/newlib/libc/reent/readr.c:49: undefined reference to `_read'
/opt/arm/9/gcc-arm-9.2-2019.12-x86_64-arm-none-eabi/bin/../lib/gcc/arm-none-eabi/9.2.1/../../../../arm-none-eabi/bin/ld: /opt/arm/9/gcc-arm-9.2-2019.12-x86_64-arm-none-eabi/bin/../lib/gcc/arm-none-eabi/9.2.1/../../../../arm-none-eabi/lib/libc.a(lib_a-fstatr.o): in function `_fstat_r':
/tmp/dgboter/bbs/rhev-vm10--rhe6x86_64/buildbot/rhe6x86_64--arm-none-eabi/build/src/newlib-cygwin/newlib/libc/reent/fstatr.c:55: undefined reference to `_fstat'
/opt/arm/9/gcc-arm-9.2-2019.12-x86_64-arm-none-eabi/bin/../lib/gcc/arm-none-eabi/9.2.1/../../../../arm-none-eabi/bin/ld: /opt/arm/9/gcc-arm-9.2-2019.12-x86_64-arm-none-eabi/bin/../lib/gcc/arm-none-eabi/9.2.1/../../../../arm-none-eabi/lib/libc.a(lib_a-isattyr.o): in function `_isatty_r':
/tmp/dgboter/bbs/rhev-vm10--rhe6x86_64/buildbot/rhe6x86_64--arm-none-eabi/build/src/newlib-cygwin/newlib/libc/reent/isattyr.c:52: undefined reference to `_isatty'
$

使用--specs=nosys.specs 选项：

/opt/arm/9/gcc-arm-9.2-2019.12-x86_64-arm-none-eabi/bin/arm-none-eabi-gcc --specs=nosys.specs -o hello hello.c 
$

如果您想自定义实现那些缺少的系统调用，另一种方法是从newlib libgloss/arm/syscalls.c 源文件创建您自己的最小syscalls.c：您可以实现一些系统调用和存根其他你不需要的。 newlib源代码可以从here浏览，更多详情参见newlibdocumentation的12 System Calls和12.1 Definitions for OS interface部分。