1 Jarkko's How to build Configure tweaked by Nick and Merijn, and now
2 maintained by perl5-metaconfig
4 The Configure script and config_h.SH file in the Perl distribution are
5 generated by a program called metaconfig. Metaconfig was originally
6 written by Larry Wall, and was subsequently enhanced and maintained
7 by Raphael Manfredi. The binary that invokes the generation of the
8 Configure file is called mconfig.
10 As sort order and filenaming are vital in this process, make sure you
11 are working on a case-sensitive file system! (Case preserving is not
14 You have presumably obtained the metaconfig from the repository e.g.
16 $ git clone git@github.com:Perl/metaconfig metaconfig
18 When working with metaconfig you will generally have two git checkouts
19 next to each other: (1) this metaconfig checkout; and (2) a checkout of
20 the Perl source code in which you will generate a new Configure script. In this
21 README, we will refer to these directories as the 'metaconfig' directory and
24 Since these two directories are normally next to each other, so ../perl
25 will get you to perl and ../perl/../metaconfig will get you back here.
26 You should establish a symbolic link to the checkout in which Configure
27 is generated such as this:
32 We will do the reverse symlinks later.
34 Contents of this directory:
37 U: Metaconfig units used for building Perl's Configure
39 a git clone of "dist". Optionally present. See (a) below.
40 This is where dist/meta resides as of 2016-04-01
42 The folder where the original units from dist are in.
43 These may differ from dist-git, as upstream also moves
48 (a) In order to assemble Configure from its units, you need mlint/metaline and
49 mconfig/metaconfig from the "dist" package installed and available in your
50 $PATH. You can either use the version that comes with your OS (Debian ships
51 it) or the versions that are included in this checkout: just add the full
52 name of this folder/bin to your $PATH. If you are not planning to analyse
53 differences of the current state with upstream dist, you can skip the rest
56 If you also want to play with or compare to the original meta/dist, you
57 can checkout that too.
59 The dist version used for perl is dist-3.5-20 in this directory, which is
60 a slightly modified version of the original, which you can get at GITHUB
61 repository https://github.com/rmanfredi/dist.git. If you'd like to keep
62 up to date with changes in dist, you can use git to create your own clone.
63 For git, that would be something like:
65 $ git clone https://github.com/rmanfredi/dist.git dist-git
67 Unsurprisingly 'dist' uses (its) Configure to generate itself:
69 $ cd dist-3.5-20 # or dist-git
70 $ chmod -R +w . # We have derived files in git :-(
75 After make install, remove lib/U/d_debugging.U in your target lib, as perl
76 uses its own way to set/define debugging (see INSTALL)
78 dist's 'Configure' is similar to perl's but perhaps not quite as polished.
80 There are some perl specific "dist units" in the 'U' directory.
81 The U directory also contains some patches to 'dist' which have already
82 been applied to dist-3.5-20 directory.
84 (aa) We have not yet arranged for metaconfig to use perl's versions of the
85 'units' by default so you need some housekeeping in the perl directory...
87 Add metaconfig/bin to your $PATH or create aliases like
89 $ export MC5=/your/path/to/metaconfig
90 $ alias ml="perl $MC5/bin/mlint -O"
91 $ alias mc="perl $MC5/bin/mconfig -m -O"
93 examples in the rest of this README will just refer to mlint and mconfig
94 as if they appear in your $PATH
98 If you plan to make changes to mconfig or mlint locally (and you might
99 want to, as both are written for perl4), consider installing mconfig and
100 mlint from the cmon subdirectory into your $PATH too. These are the
101 non-autoloading versions and can easily be changed. As these are used by
102 all team members, please communicate changes on github first.
104 (b) You need to be in the 'perl' checkout directory, which you created the
105 symbolic link to, in preparation. In this working directory, you need
106 symbolic links too, which are already known to perl itself to ignore.
107 Assuming you have metaconfig and perl side by side on the same level:
108 ln -s ../metaconfig/U U
109 ln -s ../metaconfig/.package .package
110 ln -s MANIFEST MANIFEST.new
111 chmod +w Configure config_h.SH Porting/Glossary Porting/config*
113 (c) Create a new file for the unit as U/foo/d_bar.U
114 ('foo' is one of the existing folders in U except for 'all'. If you are
115 modifying a unit already in dist, simply copy the dist version to
116 'modified' as a starting point. Otherwise, create a new file in one of the
117 other directories. It most likely will be 'perl', but it could also be
118 'compline' or any other existing folder). Choose the best appropriate
119 subdir of U. See U/README for a description of the various subdirectories.
120 You should choose the closest existing unit file as a starting point, and
121 first copy it to the new file. For example, the unit for seeing if
122 strtold_l() exists was created as U/threads/d_strtold_l.U, copied from
123 perl/d_strtold.U, then adjusted. It goes under 'threads' because it is
124 used only on threaded perls.
126 (d) Run "mlint -O" to see nits: as opposed to lint, the gripings of mlint
127 are usually serious and need fixing
129 Without -O, exceptions are lots of
130 Your private U/modified/issymlink.U overrides the public one.
131 due to the perl special units
135 "End.U": stale ?MAKE: dependency '$W'.
137 which is apparently normal ...
139 -- the next steps are in the perl folder, though the instructions below include
140 a 'cd perl' at each step, as a reminder. If you already are in 'perl',
141 disregard the reminders.
143 (e) There is a chicken and egg problem for newly created units. To get around
144 this, for such a unit, edit the file metaconfig.h and add to the comment
145 the appropropriate name. To continue the example above, we would add the
146 string HAS_STRTOLD_L at the end of the comment. This can be removed once
147 the code base has actual uses of the unit.
149 (f) "mconfig -m -O" to regenerate Configure and config_h.SH
151 Make *sure* your mconfig is the correct one in your $PATH, as the mono-web
152 package will install /usr/bin/mconfig which will do something completely
155 (g) metaconfig does not deal with depends in config_h.SH, so some
156 reorganization is needed.
159 $ perl Porting/config_h.pl
161 will fix the ordering
163 (h) The messy semi-automated part is that the knowledge of the new symbol
164 needs to be propagated to non-Configure lands like Win32, WinCE, Netware,
165 VMS, VOS, ... see previous Configure changes to see which are these
166 heathen lands. Files to take care of are
167 {win32,wince,NetWare}/config_[hH]*, (Win32, WinCE, NetWare),
168 configure.com (VMS). Depending on the kind of patch djgpp/config* might
169 also need adjusting (for example when adding/changing the list of
172 Most can be checked and updated by a tool Nicholas provided:
175 $ perl Porting/checkcfgvar.pl
177 and if it shows differences, use one of:
179 $ perl Porting/checkcfgvar.pl --regen --default=undef
180 $ perl Porting/checkcfgvar.pl --regen --default=define
182 based on the changes you made. For safety, probes should probably be
183 'undef', whereas some other things unconditionally should default to
184 'define'. For example, 'default_inc_excludes_dot' should be 'define'
185 except in very limited circumstances, because it closes a security hole.
187 For Win32 the process is semi-automated. You have to have a Win32
188 machine to run dmake on to complete the process, but that can be done
189 later by someone with such access.
191 For VMS, ('configure.com'), it may be best to add the units as 'undef' and
192 let the VMS experts deal with them later. However, you can set them to
193 'define' if they are non-tricky (such as being basic functions having
194 standard signatures across architectures), and are in the oldest release of
195 VMS that perl can be compiled on, which is 7.3-2. Appendix A of "HP C
196 Run-Time Library Reference Manual for OpenVMS Systems" gives you that
197 information. As of October 2017, the latest version online is available
198 at: http://h41379.www4.hpe.com/doc/84final/5763/5763profile.html
200 In configure.com, if there is an existing probe that is essentially the
201 same (except for the names) as the one you're adding, you can copy, paste,
202 and adjust to create a new one, but note that it's easy to run afoul of the
203 quoting rules in configure.com. New probed-for units likely will require
204 at least 2 groups of changes.
206 Rerun checkcfgvar.pl until you've fixed everything it finds.
208 (i) Check if U/mkglossary (right near the top) points to where you keep
209 dist's standard metaconfig units as well as your perl-specific ones.
211 (j) Run the perl build chain
214 $ make veryclean # Only if Configure already has been run
215 $ ./Configure -Duse64bitall -Dusethreads -Dusedevel -des
216 $ perl regen/uconfig_h.pl
218 Then make and make test or make test_harness
221 $ env TEST_JOBS=13 make test_harness
223 Before you start committing, make sure that
229 (k) Optionally, run Porting/mksample to freshen the Porting/config*.
230 Adjust the various compile-time options (e.g. 64bit, threads) as
232 You can skip this step, it's not essential, just good housekeeping.
234 Most of this only works if you have run the core-tests with the new
237 (kk) Run U/mkgloss.pl to freshen Porting/Glossary
239 You should at least check
241 $ perl U/mkgloss.pl | diff Porting/Glossary -
243 This will show two warnings that you can ignore:
245 U/mkglossary: couldn't find libdb_needs_pthread
246 U/mkglossary: couldn't find libdirs
248 all other things need a review
250 -- the next steps are in the metaconfig folder again
252 (l) git add U/foo/bar.U when you are ready ...
254 (m) git commit -m "Your commit description"
256 (n) When all patches are applied, tested and committed, and you are happy,
261 Documentation on 'dist' may be found at these locations:
262 https://github.com/rmanfredi/dist/blob/master/mcon/man/mconfig.SH
263 https://manpages.debian.org/stretch/dist/metaconfig.1.en.html
267 Tags are maintained in this git repository mapping the version of the
268 units that were used for the Configure in a given release of perl,
269 named simply after the version of perl in question (for example, at
270 the time of writing the current stable release is 5.26.1). This provides
271 a stable reference for downstreams wishing to import the metaconfig units
272 into their own packaging. Therefore, at minimum tags for each stable
273 release should be made (adding tags for development releases being an