1You're reading ./Cross/README.new, describing Perl cross-compilation process.
2NOTE: this file will replace ./Cross/README, after the cross-compilation scheme
3is stabilized.
4
5=head1 NAME
6
7README.new - Cross-compilation for linux
8
9=head1 DESCRIPTION
10
11This is second approach to linux cross-compilation, which should allow
12building full perl and extensions for target platform.
13
14We refer to HOST as the platform where the build is performed, and to
15TARGET as where final executables will run.
16
17=head2 Basic ideas
18
19=head3 common
20
21Output files from GCC cross-compiler are produced in the same
22directory where C files are. All TARGET binaries have different extensions
23so to distinguish HOST and TARGET binaries. Namely, object files for C<arm>
24cross-compilation will have extension C<.armo>, executable files will have
25C<.arm>.
26
27After typical cross-compilation the following files will be built, among
28others:
29
30  sv.c
31  sv.o
32  sv.armo
33  libperl.arma
34
35(this approach may be reconsidered, however.)
36
37=head3 build process
38
39C<miniperl> is built. This executable is intended to run on HOST, and it
40will facilitate the remaining build process; all binaries built after it are
41foreign (TARGET) and should not run locally (HOST).
42
43Unlike HOST build, miniperl will not have C<Config.pm> of HOST within reach;
44it rather will use the C<Config.pm> from the cross-compilation directories.
45In fact, if the build process does have Config.pm within reach, this is only
46an indication of a mistake somewhere in the middle.
47
48  # following command is okay:
49  ./miniperl -Ilib -MCross -MConfig -e 1
50  # following command should cluck, and it is bad if it does not:
51  ./miniperl -Ilib -MConfig -e 1
52
53After C<miniperl> is built, C<configpm> is invoked to create an
54appropriate C<Config.pm> in the right place and its corresponding
55C<Cross.pm>.
56
57File C<Cross.pm> is dead simple: for given cross-architecture places in @INC
58a path where perl modules are, and right C<Config.pm> in that place.
59
60That said, C<miniperl -Ilib -MConfig -we 1> should report an error, because
61it cannot find C<Config.pm>. If it does not give an error, a wrong C<Config.pm>
62is substituted, and resulting binaries will be a mess.
63
64C<miniperl -MCross -MConfig -we 1> should run okay, and it will provide a
65correct C<Config.pm> for further compilations.
66
67During extensions build phase, the script C<./ext/util/make_ext_cross> is
68invoked.
69
70All invocations of C<Makefile.PL> are provided with C<-MCross> so to enable
71cross-compilation.
72
73=head2 BUILD
74
75=head3 Tools & SDK
76
77To compile, you need the following:
78
79=over 4
80
81=item * TODO
82
83=back
84
85=head1 Things to be done
86
87=over 4
88
89=item * better distinguishing of config.h/xconfig.h, dependencies
90
91=item * object files created in ./xlib/cross-name/ ?
92
93=back
94