An introduction: I'm one of the two GSoC students [1][2] working on making Debian easier to bootstrap, which of course requires cross building at least enough packages to have a system capable of natively building other packages.
[1]: http://wiki.debian.org/SummerOfCode2012/StudentApplications/PJMcDermott [2]: http://wiki.debian.org/SummerOfCode2012/StudentApplications/JohannesSchauer The below message was originally sent to <mailto:[email protected]> (<http://lists.mister-muffin.de/pipermail/debian-bootstrap/2012-June/000164.html>), a list setup for collaboration between our projects. - - - Wookey (and anyone else with interest and/or knowledge in this), perl-base (from src:perl) is one of the packages that must be in the base build system (it's marked "Essential: yes" and there are four dependent Perl module packages marked "Priority: required"). So it will be one of the packages I have to make sure can be cross built. But when someone asked me a week ago about writing a program in Perl for my embedded distro project [1], I realized that the Perl interpreter can't really be cross built (my goal in that project is to cross build every package). As I understood Perl's strange custom build system [2] (with both the old [3] and new [4] cross compilation methods), it seemed like it requires some commands to be executed on the host (using GNU Autoconf terminology) system. (Perl's "Configure" script in fact runs ssh and scp commands to connect to the host system.) This can hardly be called cross building and isn't something that an OS distribution can feasibly do. So, Wookey, I watched again your DC11 talk [5] and noticed that Colin Watson said that Perl had been fixed to cross build properly. I found through the BTS [6] bugs #633884 [7] and #285559 [8], each of which has a patch against an older version of Perl and hasn't been resolved. (I also stumbled upon a rather intrusive patch [9] in Cross LFS - Sysroot.) And the src:perl versions in sid and experimental still lack cross building support. The patch Steve McIntyre posted to #633884 applies to src:perl 5.12.4-1. However, the versions in sid and experimental are 5.14.2-11 and 5.16.0-1, respectively. So I plan on looking through the upstream build system and debian/rules to see what's changed in the newer versions and how the patch might have to be updated. I don't yet have an sbuild chroot setup with a cross toolchain, so I can't test the patch. Also, I suppose I should at least forward any updated patch upstream, as the src:perl maintainers would like comments from upstream. (Surprisingly, it seems [10] no one has reported this as an issue upstream.) Fortunately for both of those points (version differences and upstream submission), the proposed patch is fairly unintrusive in the upstream code. It only: * adds cross configurations for armel and armhf (I'm not sure how optimal this cross config stuff is though), * adds a new "Configure" file in Cross/, * modifies Makefile.SH, and * enables cross building (by using the Perl installation on the build system) in debian/rules. (So only one upstream file is modified.) Full list of files patched: $ echo perl-cross.debdiff; \ > grep -E '^diff|\+\+\+\+' perl-cross.debdiff | \ > sed -e 's/^diff .* / +- /' \ > -e 's/^\+\+\+\+ \(.*\)\t.*$/ | +- \1/' perl-cross.debdiff +- perl-5.12.4/debian/changelog +- perl-5.12.4/debian/patches/debian/cross-armel.diff | +- perl-5.12.4/Cross/arm-linux-gnueabi/bitcount.h | +- perl-5.12.4/Cross/arm-linux-gnueabi/config.h.debug | +- perl-5.12.4/Cross/arm-linux-gnueabi/config.h.shared | +- perl-5.12.4/Cross/arm-linux-gnueabi/config.h.static | +- perl-5.12.4/Cross/arm-linux-gnueabi/config.sh.debug | +- perl-5.12.4/Cross/arm-linux-gnueabi/config.sh.shared | +- perl-5.12.4/Cross/arm-linux-gnueabi/config.sh.static | +- perl-5.12.4/Cross/arm-linux-gnueabi/uudmap.h +- perl-5.12.4/debian/patches/debian/cross-armhf.diff | +- perl-5.12.4/Cross/arm-linux-gnueabihf/bitcount.h | +- perl-5.12.4/Cross/arm-linux-gnueabihf/config.h.debug | +- perl-5.12.4/Cross/arm-linux-gnueabihf/config.h.shared | +- perl-5.12.4/Cross/arm-linux-gnueabihf/config.h.static | +- perl-5.12.4/Cross/arm-linux-gnueabihf/config.sh.debug | +- perl-5.12.4/Cross/arm-linux-gnueabihf/config.sh.shared | +- perl-5.12.4/Cross/arm-linux-gnueabihf/config.sh.static | +- perl-5.12.4/Cross/arm-linux-gnueabihf/uudmap.h +- perl-5.12.4/debian/patches/debian/cross.diff | +- perl/Cross/Configure.cross | +- perl/Makefile.SH +- perl-5.12.4/debian/patches/series +- perl-5.12.4/debian/rules Searching the upstream development mailing list, I found [11] an archive containing a new, more sane cross build system (written for Perl 5.12.3). I have yet to look at it, so I'm not sure if it's better than the patch Steve has proposed. Either way, it of course would also have to be updated for the newer versions of Perl. Am I going in the right direction with this? I figure I should work on this a bit now even though I'm not yet cross building anything, as it could take a while to enable support for cross building in src:perl. (We don't need to have this one package holding us back from natively bootstrapping the rest of the archive.) I just hope the other language interpreters don't have similarly strange build systems (or are at least bootstrappable)... Should I escalate the severity of #633884 from wishlist, since we need src:perl to cross build? And is it worth trying to get cross building support into wheezy's src:perl before the freeze? [1]: http://os.pehjota.net/ [2]: http://perl5.git.perl.org/perl.git/blob/7a04c38f:/INSTALL#l1707 [3]: http://perl5.git.perl.org/perl.git/blob/7a04c38f:/Cross/README [4]: http://perl5.git.perl.org/perl.git/blob/7a04c38f:/Cross/README.new [5]: http://penta.debconf.org/dc11_schedule/events/745.en.html [6]: http://bugs.debian.org/cgi-bin/[email protected]&tag=cross [7]: http://bugs.debian.org/cgi-bin/bugreport.cgi?bug=633884 [8]: http://bugs.debian.org/cgi-bin/bugreport.cgi?bug=285559 [9]: http://patches.cross-lfs.org/sysroot-dev/perl-5.10.0-cross_compile-1.patch [10]: https://rt.perl.org/rt3/Public/Search/Simple.html?q=cross [11]: http://www.xray.mpe.mpg.de/mailing-lists/perl5-porters/2011-03/msg00433.html -- P. J. McDermott (_/@\_) ,--. http://www.pehjota.net/ o < o o > / oo \ http://www.pehjota.net/contact.html o \ `-/ | <> |. o o o "~v /_\--/_/ -- To UNSUBSCRIBE, email to [email protected] with a subject of "unsubscribe". Trouble? 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