Porting with Configure

This section explains how to add programs, host and target configuration names, and site-specific information to Cygnus configure.

• Programs: Adding configure to new programs
• Hosts and Targets: Adding hosts and targets
• Sites: Adding site info

Adding Configure To New Programs

If you are writing a new program, you probably shouldn't worry about porting issues or configure until it is running reasonably on some host. Then refer back to this section.

If the program in question currently has a configure script that meets the criteria set out by standards.text, please do not add Cygnus configure. It should be possible to add this program without change to a Cygnus configure style source tree.

If the program is not target dependent, please consider using autoconf instead of Cygnus configure. autoconf will be available soon from the FSF.

To add Cygnus configure to an existing program, do the following:

Make sure the Makefile conforms to GNU standard

The coding standard for GNU Makefiles is described in standards.text.

Add Cygnus extensions to the Makefile

These are described in section Extensions to the GNU coding standards.

Move host support from Makefile to fragments

This usually involves finding sections of the Makefile that say things like "uncomment these lines for host foo" and moving them to a new file called `./config/mh-foo'. For more information, see section Adding hosts and targets.

Choose defaults

If the program has compile time options that determine the way the program should behave, chose reasonable defaults and make these Makefile variables. Be sure the variables are assigned their default values before the #### line so that site specific Makefile fragments can override them (see section Extensions to the GNU coding standards).

Locate configuration files

If there is configuration information in header files or source files, separate it in such a way that the files have a generic name. Then move the specific instances of those files into the `./config' directory.

Separate host and target information

Some programs already have this information separated. If yours does not, you will need to separate these two kinds of configuration information. Host specific information is the information needed to compile the program. Target specific information is information on the format of data files that the program will read or write. This information should live in separate files in the `./config' directory with names that reflect the configuration for which they are intended. At this point you might skip this step and simply move on. If you do, you should end up with a program that can be configured only to build native tools, that is, tools for which the host system is also the target system. Later, you could attempt to build a cross tool and separate out the target specific information by figuring out what went wrong. This is often simpler than combing through all of the source code.

Write configure.in

Usually this involves writing shell script fragments to map from canonical configuration names into the names of the configuration files. These files will then be linked at configure time from the specific instances of those files in `./config' to file in the build directory with more generic names. (see also section Build Directories). The format of configure.in is described in section The format of the `configure.in' file.

Rename `Makefile' to `Makefile.in'

At this point you should have a program that can be configured using Cygnus configure.

Adding hosts and targets

To add a host or target to a program that already uses Cygnus configure, do the following.

• Make sure the new configuration name is represented in `config.sub'. If not, add it. For more details, see the comments in the shell script `config.sub'.
• If you are adding a host configuration, look in `configure.in', in the per-host section. Make sure that your configuration name is represented in the mapping from host configuration names to configuration files. If not, add it. Also see section The format of the `configure.in' file.
• If you are adding a target configuration, look in `configure.in', in the per-target section. Make sure that your configuration name is represented in the mapping from target configuration names to configuration files. If not, add it. Also see section The format of the `configure.in' file.
• Look in `configure.in' for the variables `files', `links', `host_makefile_frag', and `target_makefile_frag'. The values assigned to these variables are the names of the configuration files, relative to srcdir that the program uses. Make sure that copies of the files exist for your host. If not, create them. See also section Variables available to configure.in.

This should be enough to configure for a new host or target configuration name. Getting the program to compile and run properly remains the hard work of the port.

Adding site info

If some of the Makefile defaults are not right for your site, you can build site specific Makefile fragments. To do this, do the following.

• Choose a name for your site. It must be less than eleven characters for now.
• If the program source does not have a `./config' directory, create it.
• Create a file called `./config/ms-site' where site is the name of your site. In it, set whatever Makefile variables you need to override to match your site's conventions.
• Configure the program with:

  configure ... +site=site