RTEMS 4.9.3 On-Line Library

Miscellaneous Support Files GCC Compiler Specifications File

BSP and Device Driver Development Guide

5.1: GCC Compiler Specifications File

The file bsp_specs defines the start files and libraries that are always used with this BSP. The format of this file is admittedly cryptic and this document will make no attempt to explain it completely. Below is the bsp_specs file from the PowerPC psim BSP:

%rename endfile old_endfile
%rename startfile old_startfile
%rename link old_link

*startfile:
%{!qrtems: %(old_startfile)} \
%{!nostdlib: %{qrtems: ecrti%O%s rtems_crti%O%s crtbegin.o%s start.o%s}}

*link:
%{!qrtems: %(old_link)} %{qrtems: -Qy -dp -Bstatic -e _start -u __vectors}

*endfile:
%{!qrtems: %(old_endfile)} %{qrtems: crtend.o%s ecrtn.o%s}

The first section of this file renames the built-in definition of some specification variables so they can be augmented without embedded their original definition. The subsequent sections specify what behavior is expected when the -qrtems or -qrtems_debug option is specified.

The *startfile section specifies that the BSP specific file start.o will be used instead of crt0.o. In addition, various EABI support files (ecrti.o etc.) will be linked in with the executable.

The *link section adds some arguments to the linker when it is invoked by GCC to link an application for this BSP.

The format of this file is specific to the GNU Compiler Suite. The argument used to override and extend the compiler built-in specifications is available in all recent GCC versions. The -specs option is present in all egcs distributions and gcc distributions starting with version 2.8.0.

BSP and Device Driver Development Guide