Board Config File

The board config file is where board specfic config data is stored. A board config file contains all the higher-level configuration settings. There is a rough inheritance scheme, where it is possible to base a new board description file on an existing one. There are also collections of custom procedures for common environments. For more information on adding a new board config file, go to the Adding A New Board chapter.

An example board config file for a GNU simulator is as follows. set_board_info is a procedure that sets the field name to the specified value. The procedures in square brackets [] are helper procedures. Thes are used to find parts of a tool chain required to build an executable image that may reside in various locations. This is mostly of use for when the startup code, the standard C lobraries, or the tool chain itself is part of your build tree.

      # This is a list of toolchains that are supported on this board.
      set_board_info target_install {sparc64-elf}

      # Load the generic configuration for this board. This will define any
      # routines needed by the tool to communicate with the board.
      load_generic_config "sim"

      # We need this for find_gcc and *_include_flags/*_link_flags.
      load_base_board_description "basic-sim"

      # Use long64 by default.
      process_multilib_options "long64"

      setup_sim sparc64

      # We only support newlib on this target. We assume that all multilib
      # options have been specified before we get here.
      set_board_info compiler  "[find_gcc]"
      set_board_info cflags  "[libgloss_include_flags] [newlib_include_flags]"
      set_board_info ldflags  "[libgloss_link_flags] [newlib_link_flags]"
      # No linker script.
      set_board_info ldscript "";

      # Used by a few gcc.c-torture testcases to delimit how large the
      # stack can be.
      set_board_info gcc,stack_size 16384
      # The simulator doesn't return exit statuses and we need to indicate this
      # the standard GCC wrapper will work with this target.
      set_board_info needs_status_wrapper 1
      # We can't pass arguments to programs.
      set_board_info noargs 1
      

There are five helper procedures used in this example. The first one, find gcc looks for a copy of the GNU compiler in your build tree, or it uses the one in your path. This will also return the proper transformed name for a cross compiler if you whole build tree is configured for one. The next helper procedures are libgloss_include_flags & libgloss_link_flags. These return the proper flags to compiler and link an executable image using Libgloss, the GNU BSP (Board Support Package). The final procedures are newlib_include_flag & newlib_include_flag. These find the Newlib C library, which is a reentrant standard C library for embedded systems comprising of non GPL'd code.