(configure.info.gz) Cygnus Configure Basics

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(configure.info.gz) Cygnus Configure

(configure.info.gz) Cygnus Configure in C++ Libraries

 
 7.1 Cygnus Configure Basics
 ===========================
 
 Cygnus configure does not use any generated files; there is no program
 corresponding to `autoconf'.  Instead, there is a single shell script
 named `configure' which may be found at the top of the Cygnus tree.
 This shell script was written by hand; it was not generated by
 autoconf, and it is incorrect, and indeed harmful, to run `autoconf' in
 the top level of a Cygnus tree.
 
    Cygnus configure works in a particular directory by examining the
 file `configure.in' in that directory.  That file is broken into four
 separate shell scripts.
 
    The first is the contents of `configure.in' up to a line that starts
 with `# per-host:'.  This is the common part.
 
    The second is the rest of `configure.in' up to a line that starts
 with `# per-target:'.  This is the per host part.
 
    The third is the rest of `configure.in' up to a line that starts
 with `# post-target:'.  This is the per target part.
 
    The fourth is the remainder of `configure.in'.  This is the post
 target part.
 
    If any of these comment lines are missing, the corresponding shell
 script is empty.
 
    Cygnus configure will first execute the common part.  This must set
 the shell variable `srctrigger' to the name of a source file, to
 confirm that Cygnus configure is looking at the right directory.  This
 may set the shell variables `package_makefile_frag' and
 `package_makefile_rules_frag'.
 
    Cygnus configure will next set the `build' and `host' shell
 variables, and execute the per host part.  This may set the shell
 variable `host_makefile_frag'.
 
    Cygnus configure will next set the `target' variable, and execute
 the per target part.  This may set the shell variable
 `target_makefile_frag'.
 
    Any of these scripts may set the `subdirs' shell variable.  This
 variable is a list of subdirectories where a `Makefile.in' file may be
 found.  Cygnus configure will automatically look for a `Makefile.in'
 file in the current directory.  The `subdirs' shell variable is not
 normally used, and I believe that the only directory which uses it at
 present is `newlib'.
 
    For each `Makefile.in', Cygnus configure will automatically create a
 `Makefile' by adding definitions for `make' variables such as `host'
 and `target', and automatically editing the values of `make' variables
 such as `prefix' if they are present.
 
    Also, if any of the `makefile_frag' shell variables are set, Cygnus
 configure will interpret them as file names relative to either the
 working directory or the source directory, and will read the contents of
 the file into the generated `Makefile'.  The file contents will be read
 in after the first line in `Makefile.in' which starts with `####'.
 
    These `Makefile' fragments are used to customize behaviour for a
 particular host or target.  They serve to select particular files to
 compile, and to define particular preprocessor macros by providing
 values for `make' variables which are then used during compilation.
 Cygnus configure, unlike autoconf, normally does not do feature tests,
 and normally requires support to be added manually for each new host.
 
    The `Makefile' fragment support is similar to the autoconf
 `AC_SUBST_FILE' macro.
 
    After creating each `Makefile', the post target script will be run
 (i.e., it may be run several times).  This script may further customize
 the `Makefile'.  When it is run, the shell variable `Makefile' will
 hold the name of the `Makefile', including the appropriate directory
 component.
 
    Like an autoconf generated `configure' script, Cygnus configure will
 create a file named `config.status' which, when run, will automatically
 recreate the configuration.  The `config.status' file will simply
 execute the Cygnus configure script again with the appropriate
 arguments.
 
    Any of the parts of `configure.in' may set the shell variables
 `files' and `links'.  Cygnus configure will set up symlinks from the
 names in `links' to the files named in `files'.  This is similar to the
 autoconf `AC_LINK_FILES' macro.
 
    Finally, any of the parts of `configure.in' may set the shell
 variable `configdirs' to a set of subdirectories.  If it is set, Cygnus
 configure will recursively run the configure process in each
 subdirectory.  If the subdirectory uses Cygnus configure, it will
 contain a `configure.in' file but no `configure' file, in which case
 Cygnus configure will invoke itself recursively.  If the subdirectory
 has a `configure' file, Cygnus configure assumes that it is an autoconf
 generated `configure' script, and simply invokes it directly.
 

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(configure.info.gz) Cygnus Configure

(configure.info.gz) Cygnus Configure in C++ Libraries