
                              Configuring egcs
                                      
   Like most GNU software, egcs must be configured before it can be
   built. This document attempts to describe the recommended
   configuration procedure for both native and cross targets.
   
   We use _srcdir_ to refer to the toplevel source directory for egcs; we
   use _objdir_ to refer to the toplevel build/object directory for egcs.
   
   First, we _highly_ recommend that egcs be built into a separate
   directory than the sources which does _not_ reside within the source
   tree. This is how we generally build egcs; building where _srcdir_ ==
   _objdir_ should still work, but doesn't get extensive testing;
   building where _objdir_ is a subdirectory of _srcdir_ is unsupported.
   
   Second, when configuring a native system, either "cc" or "gcc" must be
   in your path or you must set CC in your environment before running
   configure. Otherwise the configuration scripts may fail.
   
   To configure egcs:
   
     % mkdir _objdir_
     % cd _objdir_
     % _srcdir_/configure _[target]_ _[options]_
     
   _target specification_
     * egcs has code to correctly determine the correct value for _target_
       for nearly all native systems. Therefore, we highly recommend you
       not provide a configure target when configuring a native compiler.
     * _target_ must be specified when configuring a cross compiler;
       examples of valid targets would be i960-rtems, m68k-coff, sh-elf,
       etc.
       
   _options specification_
   
   Use _options_ to override several configure time options for egcs. A
   partial list of supported options:
     * --prefix=_dirname_ -- Specify the toplevel installation directory.
       This is the recommended way to install the tools into a directory
       other than the default. The toplevel installation directory
       defaults to /usr/local.
       We _highly_ recommend against _prefix_ being the same or a
       subdirectory of _objdir_ or vice versa.
       These additional options control where certain parts of the
       distribution are installed. Normally you should not need to use
       these options.
          + --with-local-prefix=_dirname_ -- Specify the installation
            directory for local include files. The default is /usr/local.
          + --with-gxx-include-dir=_dirname_ -- Specify the installation
            directory for g++ header files. The default is
            /usr/local/include/g++.
     * --enable-shared -- Build shared versions of the C++ runtime
       libraries if supported --disable-shared is the default.
     * --enable-haifa -- Enable the new Haifa instruction scheduler in
       the compiler; the new scheduler can significantly improve code on
       some targets.
       For egcs-1.0.x releases --disable-haifa is the default on all
       platforms except the HPPA.
       For newer releases --disable-haifa is the default on all platforms
       except the alpha, hppa, powerpc, rs6000, SPARC and m32r.
     * --with-gnu-as -- Specify that the compiler should assume the GNU
       assembler (aka gas) is available.
     * --with-gnu-ld -- Specify that the compiler should assume the GNU
       linker (aka gld) is available.
     * --with-stabs -- Specify that stabs debugging information should be
       used instead of whatever format the host normally uses. Normally
       GCC uses the same debug format as the host system.
     * --enable-multilib -- Specify that multiple target libraries should
       be built to support different target variants, calling
       conventions, etc. This is the default.
     * --enable-threads -- Specify that the target supports threads. This
       only effects the Objective-C compiler and runtime library.
     * --enable-threads=_lib_ -- Specify that _lib_ is the thread support
       library. This only effects the Objective-C compiler and runtime
       library.
     * --with-cpu=_cpu_ -- Specify which cpu variant the compiler should
       generate code for by default. This is currently only supported on
       the some ports, specifically arm, powerpc, and SPARC. If configure
       does not recognize the model name (e.g. arm700, 603e, or
       ultrasparc) you provide, please check the configure script for a
       complete list of supported models.
     * --enable-target-optspace -- Specify that target libraries should
       be optimzied for code space instead of code speed. This is the
       default for the m32r platform.
     * --enable-cpp -- Specify that a shell script which emulates
       traditional cpp functionality should be installed.
     * --enable-cpplib -- Specify that the functionality of CPP should be
       integrated into the compiler itself. This is still under
       development, but may be useful in limited situations. This option
       is never enabled by default.
     * --with-fast-fixincludes -- Specify that a newer and faster method
       of fixing the system header files should be used. This feature is
       still under development, but we are interested in feedback from
       folks that want to try it. This option is never enabled by
       default..
     * --enable-version-specific-runtime-libs -- Specify that runtime
       libraries should be installed in the compiler specific
       subdirectory (${libsubdir}) rather than the usual places. In
       addition, libstdc++'s include files will be installed in
       ${libsubdir}/include/g++ unless you overruled it by using
       --with-gxx-include-dir=_dirname_. Using this option is
       particularly useful if you intend to use several versions of
       egcs/gcc in parallel. This is currently supported by libf2c and
       libstdc++.
     * --enable-languages=_lang1_,_lang2_,... -- Specify that only a
       particular subset of compilers and their runtime libraries should
       be built. For a list of valid values for _lang_x you can issue the
       following command in the gcc directory of your egcs source tree:
       grep language= */config-lang.in
       Currently, you can use any of the following: CHILL, c++, f77, java
       and objc. Please note, that this switch will only work with recent
       snapshots (for instance, newer snapshots than 19981126 should do);
       it does not work with any egcs releases up to and including 1.1.1,
       though!
       If you do not pass this flag, all languages available in the gcc
       sub-tree will be configured. Re-defining LANGUAGES when calling
       make bootstrap _*does not*_ work anymore, as those language
       sub-directories might not have been configured!
     * --with-dwarf2 -- Specify that the compiler should use DWARF2
       debugging information as the default.
       
   Some options which only apply to building cross compilers:
     * --with-headers=_dir_ -- Specifies a directory which has target
       include files. These include files will be copied into the egcs
       install directory. Fixincludes will be run on these files to make
       them compatible with egcs.
     * --with-libs=_dirs_ -- Specifies a list of directories which
       contain the target runtime libraries. These libraries will be
       copied into the egcs install directory.
     * --with-newlib -- Specifies that "newlib" is being used as the
       target C library. This causes __eprintf to be omitted from
       libgcc.a on the assumption that it will be provided by newlib.
       
   Note that each --enable option has a corresponding --disable option
   and that each --with option has a corresponding --without option.
     _________________________________________________________________
   
   _Last modified on Dec 6, 1998._
