cross-compilation for linux

From: "Konovalov, Vadim Vladimirovich \(Vadim\)** CTR **" <vkonovalov@alcatel-lucent.com>
Message-ID: <D16F05D0CAAA234BA2B753B80DE6100D278EBC@DEEXC1U02.de.lucent.com>

p4raw-id: //depot/perl@31362

1 files changed, 89 insertions, 0 deletions

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+You're reading ./Cross/README.new, describing Perl cross-compilation process.
+NOTE: this file will replace ./Cross/README, after cross-compilation scheme
+will stabilize;
+
+=head1 Cross-compilation for linux
+
+This is second approach to linux cross-compiling, which should allow building
+full perl and entensions for target platform. Cross-compiling for linux
+uses similar approach and share same files as cross-compiling for WINCE.
+
+We refer to HOST as the platform where the build is performed, and to
+TARGET as where final executables will run.
+
+=head2 Basic ideas
+
+=head3 common
+
+Unlike WINCE, output files from GCC cross-compiler are produced in the same
+directory where C files are. All TARGET binaries have different extensions
+so to distinguish HOST and TARGET binaries. Namely, object files for C<arm>
+cross-compilation will have extension C<.armo>, executable files will have
+C<.arm>.
+
+After typical cross-compilation the following files will be built, among
+others:
+
+  sv.c
+  sv.o
+  sv.armo
+  libperl.arma
+
+(this approach may be reconsidered, however.)
+
+=head3 build process
+
+C<miniperl> is built. This executable is intended to run on HOST, and it
+will facilitate the remaining build process; all binaries built after it are
+foreign (TARGET) and should not run locally (HOST).
+
+Unlike HOST build, miniperl will not have C<Config.pm> of HOST within reach;
+it rather will use the C<Config.pm> from the cross-compilation directories.
+In fact, if the build process does have Config.pm within reach, this is only
+an indication of a mistake somewhere in the middle.
+
+  # following command is okay:
+  ./miniperl -Ilib -MCross -MConfig -e 1
+  # following command should cluck, and it is bad if it does not:
+  ./miniperl -Ilib -MConfig -e 1
+
+After C<miniperl> is built, C<configpm> is invoked to create right C<Config.pm>
+in right place and its corresponding Cross.pm.
+
+File C<Cross.pm> is dead simple: for given cross-architecture places in @INC
+a path where perl modules are, and right C<Config.pm> in that place.
+
+That said, C<miniperl -Ilib -MConfig -we 1> should report an error, because
+it can not find C<Config.pm>. If it does not give an error -- wrong C<Config.pm>
+is substituted, and resulting binaries will be a mess.
+
+C<miniperl -MCross -MConfig -we 1> should run okay, and it will provide right
+C<Config.pm> for further compilations.
+
+During extensions build phase, the script C<./ext/util/make_ext_cross> is
+invoked.
+
+All invokes of C<Makefile.PL> are provided with C<-MCross> so to enable cross-
+compile.
+
+=head2 BUILD
+
+=head3 Tools & SDK
+
+For compiling, you need following:
+
+=over 4
+
+=item * TODO
+
+=back
+
+=head1 Things to be done
+
+=over 4
+
+=item * better distinguishing of config.h/xconfig.h, dependancies
+
+=item * object files created in ./xlib/cross-name/ ?
+
+=back