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1 Jarkko's How to build Configure tweaked by Nick and Merijn, and now
2 maintained by perl5-metaconfig
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3
4The Configure script and config_h.SH file in the Perl distribution are
496e2020 5generated by a program called metaconfig. Metaconfig was originally
2eb0fc7c 6written by Larry Wall, and was subsequently enhanced and maintained
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7by Raphael Manfredi. The binary that invokes the generation of the
8Configure file is called mconfig.
9
10As sort order and filenaming are vital in this process, make sure you
11are working on a case-sensitive file system! (Case preserving is not
12sufficient).
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13
14You have presumably obtained the metaconfig from the repository e.g.
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b3647673 16 $ git clone github.com:perl5-metaconfig/metaconfig metaconfig
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18When working with metaconfig you will generally have two git checkouts
19next to each other: (1) this metaconfig checkout; and (2) a checkout of
20the Perl 5 source code in which you will generate a new Configure
21script. In this README, we will refer to these directories as the
22'metaconfig' directory and the 'perl' directory.
23
24Since these two directories are normally next to each other, so ../perl
25will get you to perl and ../perl/../metaconfig will get you back here.
26You should establish a symbolic link to the checkout in which Configure
27is generated such as this:
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28
29 $ cd metaconfig
30 $ ln -s ../perl perl
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32We will do the reverse symlinks later.
33
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34Contents of this directory:
35
36 README: This file.
07438c4f 37 U: Metaconfig units used for building Perl's Configure
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38 dist-git:
39 a git clone of "dist". Optionally present. See (a) below.
40 This is where dist/meta resides as of 2016-04-01
e00c5fdc 41 dist:
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42 The folder where the original units from dist are in.
43 These may differ from dist-git, as upstream also moves
44 on and develops.
2eb0fc7c 45
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46Development workflow:
47
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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
54 op step (a) now.
1bf51bf8 55
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56 If you also want to play with or compare to the original meta/dist, you
57 can checkout that too.
1bf51bf8 58
e00c5fdc 59 The dist version used for perl is dist-3.5-20 in this directory, which is
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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:
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e412846d 65 $ git clone https://github.com/rmanfredi/dist.git dist-git
1e695180 66
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67 Unsurprisingly 'dist' uses (its) Configure to generate itself:
68
e412846d 69 $ cd dist-3.5-20 # or dist-git
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70 $ chmod -R +w . # We have derived files in git :-(
71 $ ./Configure
72 $ make
73 $ make install
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e00c5fdc 75 After make install, remove lib/U/d_debugging.U in your target lib, as perl
07438c4f 76 uses its own way to set/define debugging (see INSTALL)
e00c5fdc 77
e00c5fdc 78 dist's 'Configure' is similar to perl's but perhaps not quite as polished.
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79
80 There are some perl specific "dist units" in the 'U' directory.
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81 The U directory also contains some patches to 'dist' which have already
82 been applied to dist-3.5-20 directory.
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83
84(aa) We have not yet arranged for metaconfig to use perl's versions of the
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85 'units' by default so you need some housekeeping in the perl directory...
86
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87 Then add metaconfig/bin to your $PATH or create aliases like
88
89 $ export MC5=/your/path/to/metaconfig
90 $ alias ml="perl $MC5/bin/mlint -O"
19cf191d 91 $ alias mc="perl $MC5/bin/mconfig -m -O"
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92
93 examples in the rest of this README will just refer to mlint and mconfig
94 as if they appear in your $PATH
95
496e2020 96(aaa)
352aa7ee 97
b3647673 98 If you plan to make changes to mconfig or mlint locally (and you might
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99 want to, as both are written for perl4), consider installing mconfig and
100 mlint from the cmon subdirectory into your $PATH too. These are the
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101 non-autoloading versions and can easily be changed. As these are used by
102 all team members, please communicate changes on github first.
103
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104(b) You need to be in the 'perl' checkout directory, which you created the
105 symbolic link to, in preparation. In this working directory, you need
106 symbolic links too, which are already known to perl itself to ignore.
107 Assuming you have metaconfig and perl side by side on the same level:
108 ln -s ../metaconfig/U U
109 ln -s ../metaconfig/.package .package
110 ln -s MANIFEST MANIFEST.new
111 chmod +w Configure config_h.SH Porting/Glossary Porting/config*
112
113(c) Create a new file for the new unit as U/foo/d_bar.U
114 ('foo' is one of the existing folders in U except for 'all'. It most
115 likely will be 'perl', but it could also be 'modified', 'compline' or any
116 other existing folder). Choose the best appropriate subdir of U. See
117 U/README for a description of the various subdirectories.) You should
118 choose the closest existing unit file as a starting point, and first copy
119 it to the new file. For example, the unit for seeing if strtold_l() exists
120 was created as U/threads/d_strtold_l.U, copied from perl/d_strtold.U, then
121 adjusted. It goes under 'threads' because it is used only on threaded
122 perls.
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124(d) Run "mlint -O" to see nits: as opposed to lint, the gripings of mlint
125 are usually serious and need fixing
13b7c768 126
b3647673 127 Without -O, exceptions are lots of
cb69034d 128 Your private U/modified/issymlink.U overrides the public one.
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129 due to the perl special units
130
131 and
132
133 "End.U": stale ?MAKE: dependency '$W'.
134
135 which is apparently normal ...
136
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137-- the next steps are in the perl folder, though the instructions below include
138 a 'cd perl' at each step, as a reminder. If you already are in 'perl',
139 disregard the reminders.
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141(e) There is a chicken and egg problem for newly created units. To get around
142 this, for such a unit, edit the file metaconfig.h and add to the comment
143 the appropropriate name. To continue the example above, we would add the
144 string HAS_STRTOLD_L at the end of the comment. This can be removed once
145 the code base has actual uses of the unit.
b3647673 146
19cf191d 147(f) "mconfig -m -O" to regenerate Configure and config_h.SH
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148
149 Make *sure* your mconfig is the correct one in your $PATH, as the mono-web
150 package will install /usr/bin/mconfig which will do something completely
151 different.
13b7c768 152
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153(g) metaconfig does not deal with depends in config_h.SH, so some
154 reorganization is needed.
155
b3647673 156 $ cd perl
430b74fe 157 $ perl Porting/config_h.pl
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158
159 will fix the ordering
496e2020 160
b3647673 161(h) The messy semi-automated part is that the knowledge of the new symbol
974341ad 162 needs to be propagated to non-Configure lands like Win32, WinCE, Netware,
65c1af4d 163 VMS, VOS, ... see previous Configure changes to see which are these
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164 heathen lands. Files to take care of are
165 {win32,wince,NetWare}/config_[hH]*, (Win32, WinCE, NetWare),
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166 configure.com (VMS). Depending on the kind of patch djgpp/config* might
167 also need adjusting (for example when adding/changing the list of
168 extensions)
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169
170 Most can be checked and updated by a tool Nicholas provided:
171
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172 $ cd perl
173 $ perl Porting/checkcfgvar.pl
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3a12a5f5 175 and if it shows differences, use one of:
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177 $ perl Porting/checkcfgvar.pl --regen --default=undef
178 $ perl Porting/checkcfgvar.pl --regen --default=define
b3647673 179
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180 based on the changes you made. For safety, probes should probably be
181 'undef', whereas some other things unconditionally should default to
182 'define'. For example, 'default_inc_excludes_dot' should be 'define'
183 except in very limited circumstances, because it closes a security hole.
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185 For Win32 the process is semi-automated. You have to have a Win32
186 machine to run dmake on to complete the process, but that can be done
187 later by someone with such access.
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189 For VMS, ('configure.com'), it may be best to add the units as 'undef' and
190 let the VMS experts deal with them later. However, you can set them to
191 'define' if they are non-tricky (such as being basic functions having
192 standard signatures across architectures), and are in the oldest release of
193 VMS that perl can be compiled on, which is 7.3-2. Appendix A of "HP C
194 Run-Time Library Reference Manual for OpenVMS Systems" gives you that
195 information. As of October 2017, the latest version online is available
196 at: http://h41379.www4.hpe.com/doc/84final/5763/5763profile.html
197
198 In configure.com, if there is an existing probe that is essentially the
199 same (except for the names) as the one you're adding, you can copy, paste,
200 and adjust to create a new one, but note that it's easy to run afoul of the
201 quoting rules in configure.com. New probed-for units likely will require
202 at least 2 groups of changes.
203
204 Rerun checkcfgvar.pl until you've fixed everything it finds.
13b7c768 205
b3647673 206(i) Check if U/mkglossary (right near the top) points to where you keep
2eb0fc7c 207 dist's standard metaconfig units as well as your perl-specific ones.
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b3647673 209(j) Run the perl build chain
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b3647673 211 $ cd perl
496e2020 212 $ make veryclean # Only if Configure already has been run
b3647673 213 $ ./Configure -Duse64bitall -Dusethreads -Dusedevel -des
b3647673 214 $ perl regen/uconfig_h.pl
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b3647673 216 Then make and make test or make test_harness
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218 $ make -j12
219 $ env TEST_JOBS=13 make test_harness
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0a071d90 221 Before you start committing, make sure that
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223 $ make test_porting
224
0a071d90 225 still passes
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496e2020 227(k) Optionally, run Porting/mksample to freshen the Porting/config*.
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228 Adjust the various compile-time options (e.g. 64bit, threads) as
229 you see fit.
496e2020 230 You can skip this step, it's not essential, just good housekeeping.
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231
232 Most of this only works if you have run the core-tests with the new
233 generated files
234
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235(kk) Run U/mkgloss.pl to freshen Porting/Glossary
236
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237 You should at least check
238
239 $ perl U/mkgloss.pl | diff Porting/Glossary -
240
241 This will show two warnings that you can ignore:
242
243 U/mkglossary: couldn't find libdb_needs_pthread
244 U/mkglossary: couldn't find libdirs
245
246 all other things need a review
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247
248-- the next steps are in the metaconfig folder again
249
496e2020 250(l) git add U/foo/bar.U when you are ready ...
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251
252(m) git commit -m "Your commit description"
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254(n) When all patches are applied, tested and committed, and you are happy,
255 git push
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257References:
258
259Documentation on 'dist' may be found at these locations:
260https://github.com/rmanfredi/dist/blob/master/mcon/man/mconfig.SH
261https://manpages.debian.org/stretch/dist/metaconfig.1.en.html
262
263Git tags:
264
265Tags are maintained in this git repository mapping the version of the
266units that were used for the Configure in a given release of perl,
267named simply after the version of perl in question (for example, at
268the time of writing the current stable release is 5.26.1). This provides
269a stable reference for downstreams wishing to import the metaconfig units
270into their own packaging. Therefore, at minimum tags for each stable
271release should be made (adding tags for development releases being an
272optional extra).