
            ****** Building Unix Squeak (>= 3.2) from source ******

                                 Ian Piumarta
                            <ian.piumarta@inria.fr>

       Last edited: 2002-06-05 05:22:02 by piumarta on emilia.inria.fr
                Translated to .ps/.pdf/.html/.txt: June 5, 2002

***** Contents *****

    * 1_configure_-_build_-_install
    * 2_Generating_your_own_VM_and_plugin_sources
    * 3_Adding_your_own_plugins

          o 3.1_Plugin-specific_configuration
          o 3.2_Plugin-specific_Makefile_declarations_and_rules
          o 3.3_Examples_taken_from_existing_plugins
          o 3.4_Coping_with_VMMaker_quirks
          o 3.5_If_all_else_fails

    * Index

1 configure - build - install

Unix Squeak is built using the (almost) universal ``configure; make; make
install''. If you haven't come across this before, read on...

Create a build directory (which we will call `blddir' from now on) and then
`cd' to it:

  $ mkdir blddir
  $ cd blddir

A convenient place is just next to the platforms directory, like this:

  $ cd squeak
  $ ls
  platforms src ...
  $ mkdir bld
  $ cd bld

Create the build environment by running the script configure which lives in the
platforms/unix/config directory.

     Note: The configure script accepts lots of options. To see a list of
     them, run: `configure --help'

Assuming you've created the blddir next to platforms, this would be:

  $ ../platforms/unix/config/configure

     Note: This assumes that the VMMaker sources are in `../src'. However,
     since the Unix Squeak support code is independent of the image
     version from which VMMaker generated the interpreter/plugin sources,
     it is possible that your source distribution comes with more than one
     src directory (corresponding to more than one image version used to
     generate the sources). In such cases you will have to tell configure
     which source version to use, via the `--with-src' option. For
     example, if there are two source directories called src-3.2gamma-4857
     and src-3.3.alpha-4881 then you would use one of the following
     commands:

       $ .../configure --with-src=src-3.2gamma-4857
             or
       $ .../configure --with-src=src-3.3alpha-4881

Build the VM and plugins by running make:

  $ make

     Note: If you want to build just the VM (without external plugins) or
     just the external plugins (without the VM) then you can use: `make
     squeak' or `make plugins' respectively.

Finally install the VM, plugins and manual pages:

  $ su root
  $ make install

****** 2 Generating your own VM and plugin sources ******

Generating your own VM/plugin sources might be necessary for various reasons:

    * you want to change the mix of internal vs. external plugins
    * you want to remove some plugins from the VM that you will never use
    * you've pulled in some updates that modify the Interpreter or plugins
    * you've filed-in (or written) a whole new plugin
    * etc...

Version 3.2 (and later) of Unix Squeak use VMMaker to generate the core
interpreter and plugin sources.

Start Squeak in the top-level directory (the one containing the platforms
directory); for example:

  $ ls
  src platforms ...
  $ squeak MyCoolPlugin.image

Open a VMMakerTool and modify the setup to your liking.

     Note: The VMMaker configuration used to build the distributions of
     Unix Squeak is available in platforms/unix/config/VMMaker.config.

Then click on the relevant ``generate ...'' button. You can now `configure;
make; make install' in your blddir (as described above).

     Note: You only need to run configure once for a given blddir (on the
     same host). If you modify the choice of plugins (or change whether
     they're internal/external) then you can update the build environment
     by running the config.status script in the bldddir, like this:

       $ squeak MyCoolPlugin.image
       ... generate new sources ...
       $ cd blddir
       $ ./config.status
       $ make
     This is much faster than running configure all over again. (In fact,
     make should detect any changes to the plugin configuration and re-run
     config.status for you automatically.)

     Note: `configure' doesn't actually create any files. The last thing
     it does is run `config.status' to create the configured files in
     blddir from the corresponding file.ins in the unix/config directory.
     So in the remainder of this document the phrase `during
     configuration' means either when running `configure' for the first
     time or running `config.status' to update an already configured build
     environment.

****** 3 Adding your own plugins ******

     Note: This section is intended primarily for plugin developers.

If your plugin requires no platform-specific tweaks then there's nothing for
you to do. configure (and config.status) will provide a default Makefile for it
that should work. If your plugin requires only platform-independent tweaks
(and/or additional hand-written code) then these go in platforms/Cross/plugins,
and there's nothing for you to do (in Unixland).

On the other hand, if you require special configure tests or additional
declarations/rules in your plugin's Makefile then you need to specify them
explicitly.

     Note: Unix Squeak subscribes to the following philopsophy:

     Absolutely everything that is specific to Unix (sources, headers,
     configure and Makefile extensions, etc.) lives under platforms/unix.

     In other words: there is not (nor aught there be) any Unix-related
     information under the platforms/Cross directory. (Unix Squeak is
     entirely encapsulated under platforms/unix and is utterly immune to
     ``random junk'' elsewhere in the platforms tree.)

First you must create a new directory under platforms/unix/plugins named after
your plugin. This directory will hold the files describing the additional
configuration checks and/or Makefile contents. For example, if your plugin is
called ``MyCoolPlugin'' then

  $ mkdir platforms/unix/plugins/MyCoolPlugin

would be the thing to do. (The following sections will refer to this directory
as platdep since the full path is quite a mouthful of typing for my lazy
fingers.)

***** 3.1 Plugin-specific configuration *****

Your plugin can ask configure to run additional tests (and to set additional
variables in its output files) simply by including a file called acinclude.m4
in it's platdep directory.

     Note: The configure script is `compiled' from several other files. If
     you create a `platdep./acinclude.m4' file then you must `recompile'
     configure. You can do this by `cd'ing to unix/config and running
     `make', or (if you have GNU make) from the blddir like this:

       $ make -C ../platforms/unix/config

In addition to the usual autoconf macros, the following macros are available
specifically for Squeak plugins to use:

3.1.1 AC_PLUGIN_CHECK_LIB(lib,func)

This is similar to the autoconf `AC_CHECK_LIB' macro.

func is the name of a function required by the plugin, defined in the external
(system) library lib. The macro checks that the library is available (via `-
llib') and then adds it to the list of libraries required by the plugin (see
the explanation of [plibs] in Section 3.2.1 for a description of how library
dependencies for plugins are handled).

If func cannot be found in lib then the plugin will be disabled and a message
to that effect printed during configuration. (The VM can still be built,
without rerunning VMMaker or reconfiguring, and the plugin will simply be
ommitted from it.)

3.1.2 AC_PLUGIN_DEFINE_UNQUOTED(keyword,text)

This is similar to the autoconf `AC_DEFINE_UNQUOTED' macro.

keyword is a Makefile keyword (usually of the form `[name]') and text is
arbitrary text to be associated with it. Calling this macro causes mkmf to
substitute text for all occurrences of keyword in the Makefile generated for
the plugin.

**** 3.1.3 Plugin-specific variables ****

The following variables are also set during the execution of a plugin-specific
acinclude.m4:

      ${plugin} is the name of the plugin;

      ${topdir} is the path to the top-level directory (containing platforms);

      ${vmmdir} is the path to the VMMaker `src' directory.

3.2 Plugin-specific Makefile declarations and rules

Three mechanisms are avilable for this:
   1. scanning additional dirrectories for sources and headers;
   2.
      including a few additional lines into the default Makefile; and
   3.
      replacing entirely the default Makefile with a hand-written one.
(The last option isn't as scary as it might sound: read on...)

3.2.1 The anatomy of a plugin's Makefile

Before proceeding, let's take a minute to understand how Unix Squeak compiles
and links files in its default Makefile for plugins. The default Makefile looks
like this:

          # default Makefile for Unix Squeak plugins

          [make_cfg]
          [make_plg]

          XINCLUDES       = [includes]
          OBJS            = [targets]
          TARGET          = [target]
          PLIBS           = [plibs]

          [make_inc]

          $(TARGET) : $(OBJS) Makefile
                  $(LINK) $(TARGET) $(OBJS) $(PLIBS)

          [make_targets]

          .force :

     Note: The keywords appearing between `[ square brackets ]' are
     substituted during configuration by a preprocessor called `mkmf'
     according to the kind of plugin (internal/external) being built.

[make_cfg]  is the configured variable section. It contains the platform-
specific information gleaned by configure while it was figuring out which
compiler you have, what flags your linker needs, where to install stuff, and so
on.

[make_plg]  contains a handful of definitions which depend on whether the
plugin is being compiled as internal or external:

      o           the extension for object files

      a           the extension for plugins

      COMPILE     the command to compile a source file into an object file

      LINK        the command to link one or more object files into a
                  plugin

For internal plugins: $o is `.o' and $a is `.a'. $(COMPILE) is the C compiler
(`$(CC) ... -o', so the first thing after the command must be the output
filename) and $(LINK) is archiver (`ar -rc', again requiring the output file to
follow immediately). Note that internal plugins are built as `ar' archives
before being linked into the final binary.

For external plugins: $o is `.lo', $a is `.la', and $(COMPILE) and $(LINK) are
invocations of `libtool' to create position-independent objects and shared
libraries (with a `-o' appearing right at the end, so the first thing after the
command must be the output filename).

[includes]  is a list of `-Idir' compiler flags, one for each of the
directories

  src/plugins/name
  src/vm/intplugins/name
  platforms/Cross/plugins/name
  platforms/unix/plugins/name
in which at least one header file is present.

[targets]  is a list of object files corresponding to the source (.c) files
found in the directories:

  src/plugins/name/*.c
  src/vm/intplugins/name/*.c
  platforms/Cross/plugins/name/*.c
  platforms/unix/plugins/name/*.c
where each source file has been stripped of the directory name and had the `.c'
converted into `$o'.

[target]  is the name of the plugin, including the $a extension.

[plibs]  is a list of zero or more libraries on which the plugin depends (as
detected using the macro AC_PLUGIN_CHECK_LIB in the plugin-specific
acinclude.m4). If the plugin is being built internally then this list is empty
and the required libraries are included in the final link command. If the
plugin is being built externally then the plugin itself (a shared object) is
linked against these libraries (via [plist]) rather than with the main VM
binary.

(This is to ensure that a missing shared object needed by an external plugin
will only affect the operation of that plugin and not prevent the rest of the
VM from running, which would be the case if the entire VM were linked against
it.)

[make_inc]  is the contents of the Makefile.inc file in your plugin's platdep
directory (or empty if this file doesn't exist).

[make_targets]  is a list of rules for building the files listed in [targets].
Each rule looks like this:

        name$o : original/source/dir/name.c
                $(COMPILE) name$o original/source/dir/name.c

3.2.2 A note about $(COMPILE) and $(LINK) commands

You should never pass additional flags to these commands explicitly. This is
because you cannot know how they are defined. (Their definitions depend on
whether the plugin is being built internally or externally -- and might even
change radically in future releases of Unix Squeak.)

Instead you should pass additional compiler/linker flags to these commands by
setting the following variables in `Makefile.inc' or `Makefile.in':

      XCPPFLAGS     `-I' flags for cpp

      XDEFS         `-D' flags for cpp

      XCFLAGS       anything to be passed to the compiler

      XLDFLAGS      anything to be passed to the linker

     Note: `mkmf' already uses `XINCLUDES'  to pass the list of
     directories containing plugin header files to cpp. You can redefine
     it if you like, but make sure that `[includes]' appears in its
     definition (or in the definition of `XCPPFLAGS').

**** 3.2.3 Specifying additional source directories ****

mkmf looks for a file in your plugin's platdep directory called `mkmf.subdirs'.
If this file exists then it should contain a list of directory names relative
to the top-level directory (the one containing the src and platform
directories). These directories will be added to the list of locations searched
for `.c' and `.h' files while constructing the substitutions for `[includes]',
`[targets]' and `[make_targets]'.

3.2.4 Including additional material in the default Makefile

If the file platdep/Makefile.inc exists then mkmf will substitute its contents
into the Makefile in place of the [make_inc] keyword.

     Note: Makefile.inc is read into the Makefile under construction
     before mkmf performs substitutions on the `[keyword]'s. In other
     words, your Makefile.inc can use the above keywords to include
     relevant declarations and rules without worrying about whether the
     plugin is internal or external.

3.2.5 Replacing the default Makefile entirely

If neither of the above are sufficient then you can create a complete Makefile
template called platdep/Makefile.in. mkmf will use this template instead of the
default Makefile template shown earlier, and will perform keyword substitutions
on it as described above to create the final Makefile. (In other words, simply
copying the default template shown earlier will result in a Makefile identical
to the one that mkmf would have produced by default.

***** 3.3 Examples taken from existing plugins *****

By way of example we'll look at how two existing plugins specialise their
configuration and Makefiles.

**** 3.3.1 Configuration ****

The B3DAcceleratorPlugin requires OpenGL in order to compile. The file unix/
plugins/B3DAcceleratorPlugin/acinclude.m4 contains a single call to an
autoconf-style macro:

    AC_PLUGIN_SEARCH_LIBS(glIsEnabled, GL)

This works similarly to the autoconf `AC_SEARCH_LIBS' macro: If a library
libGL.{a,so} (OpenGL) exists and exports the function glIsEnabled() then `-lGL'
is added to the final VM link command. Otherwise the plugin is disabled (and a
message warning of the fact is printed).

     Note: There's a bug here. This should also check for `GL_VERSION_1_1'
     in headers.

3.3.2 Customising the Makefile

The Mpeg3Plugin requires a (modified) libmpeg to be compiled along with it. The
sources for this library are in (several) subdirectories of Cross/Meg3Plugin
and they require additional cpp definitions in order to compile correctly.

To cope with the additional directories, unix/plugins/Mpeg3Plugin/mkmf.subdirs
simply lists them:

  platforms/Cross/plugins/Mpeg3Plugin/libmpeg
  platforms/Cross/plugins/Mpeg3Plugin/libmpeg/audio
  platforms/Cross/plugins/Mpeg3Plugin/libmpeg/video

To cope with the additional cpp definitions, we could have written a tiny
Makefile.inc containing:

    XDEFS   = -DNOPTHREADS

Unfortunately the additional source directories contain various utility and
test programs (which must not be built) so we cannot rely on mkmf generating
the correct [targets] list.

Instead we just copy the default Makefile ``template'' (shown above) as
Mpeg3Plugin/Makefile.in and insert the required list of targets (and cpp
definition) manually. The end result looks like this:

          # Makefile.in for Mpeg3Plugin in Unix Squeak

          [make_cfg]
          [make_plg]

          TARGET  = Mpeg3Plugin$a

          PLUGIN  = Mpeg3Plugin$o
          VIDEO   = getpicture$o headers$o idct$o macroblocks$o
          etc...
          AUDIO   = dct$o header$o layer1$o layer2$o layer3$o etc...
          LIBMPEG = bitstream$o changesForSqueak$o libmpeg3$o etc...

          OBJS    = $(PLUGIN) $(VIDEO) $(AUDIO) $(LIBMPEG)

          XINCLUDES       = [includes]
          XDEFS           = -DNOPTHREADS

          $(TARGET) : $(OBJS) Makefile
                  $(LINK) $(TARGET) $(OBJS)

          [make_targets]

          .force :

     Note: The default `[make_targets]' will contain additional rules for
     the objects that we're trying to avoid building (because it's built
     from an exhaustive list of `.c' files in the source directories).
     This does no harm since the offending rules can never be triggered
     (their targets are not listed in `OBJS').

***** 3.4 Coping with VMMaker quirks *****

VMMaker will refuse to compile a plugin if it thinks the plugin requires
platform support. This is ``all-or-nothing'': if platform support is required
on one platform then it is required on all platforms (even if the plugin
compiles quite happily without platform support in Unix).

The easiest way to add ``null'' platform support is to place an empty
`Makefile.inc' in the plugin's platdep directory. (To see this in action, look
in unix/plugins/JPEGReadWriter2Plugin.)

***** 3.5 If all else fails *****

(Where ``all else failing'' is defined as: ``after trying for 20 minutes and
still getting nowhere''.)

If you're writing a plugin that needs platform support (beyond dumb inclusion
of a few additional `.c' files) and this document has been of no help at all
(or if you understood it but you're still suffering from ``all else failing'')
then send me mail and I'll be happy to help you with the various platdep files.

***** Index *****
  $(COMPILE)
      3.2.2
  $(LINK)
      3.2.2
  $(XCFLAGS)
      3.2.2
  $(XCPPFLAGS)
      3.2.2
  $(XDEFS)
      3.2.2
  $(XINCLUDES)
      3.2.2
  $(XLDFLAGS)
      3.2.2
  [includes]
      3.2.1
  [make_cfg]
      3.2.1
  [make_inc]
      3.2.1
  [make_plg]
      3.2.1
  [make_targets]
      3.2.1
  [plibs]
      3.2.1
  [target]
      3.2.1
  [targets]
      3.2.1
  AC_PLUGIN_CHECK_LIB
      3.1.1
  AC_PLUGIN_DEFINE_UNQUOTED
      3.1.2
  acinclude.m4
      3.1
        example
            3.3.1
  additional plugin source directories
      3.2.3
  build directory
        configuring
            1
        creating
            1
  config.status
      2
        versus configure
            2
  configure
      3.1
        macros for plugins
            3.1
        recreating
            3.1
  emergency services
      3.5
  Makefile
      3.2.1
        avoiding $(XINCLUDES)
            3.2.2
        compile/link commands
            3.2.2
        keyword substitution
            3.2.1
        passing extra flags
            3.2.2
        replacing
            3.2.5
        target rules
            3.2.1
  Makefile keywords
        [includes]
            3.2.1
        [make_cfg]
            3.2.1
        [make_inc]
            3.2.1
        [make_plg]
            3.2.1
        [make_targets]
            3.2.1
        [plibs]
            3.2.1
        [target]
            3.2.1
        [targets]
            3.2.1
  Makefile.in
      3.2.5
        example
            3.3.2
  Makefile.inc
      3.2.4
        example
            3.3.2
        keyword substitution
            3.2.4
  mkmf
      3.2.1
        additional source directories
            3.2.3
        default header directories
            3.2.1
        default source directories
            3.2.1
  mkmf.subdirs
      3.2.3
        example
            3.3.2
  plugin
        Makefile
            3.2
        Makefile anatomy
            3.2.1
        adding your own
            3
        configuring
            3.1
        target rules
            3.2.1
        Unix-specific directory
            3
  Unix-specific files
      3
  VMMaker
        configuration file
            2
        missing platform support
            3.4
        reference
            2

===============================================================================
     Ian Piumarta 2002-06-05
