[buildd-tools-devel] Multiarch buildd support (sbuild)

[Wookey]

Back at an adhoc meeting in Banja Luka with FTP, release, multiarch
and toolchain people, we agreed that making it possible to build
things using multiarch in the archive was necessary and useful for
some things, particularly cross compilers, but also bootloaders, maybe
wine and potentially some things we hadn't thought of yet.

It's taken a while to come to fruition but the pieces for this are
finally falling into place. Cross-binutils has been in the archive for
a while, cross-gcc (initial upload for cross-gcc-4.9-armhf - more
arches later when/if we see this working) is in NEW now. These
packages have been working since March but there was no point
uploading until there was a prospect of building them. That
cross-gcc-4.9-armhf build-deps on 3 foreign-arch packages:
libc6-dev:armhf, linux-libc-dev:armhf, libgcc1:armhf

sbuild 0.64.3-1 (already in testing) or later (0.64.3-2 in unstable is
nicer) will happily build such packages. However that's not the
version used on the buildds. That is currently
0.64.0-1+buildd20140816.0 in the buildd-0.64 branch at
http://anonscm.debian.org/cgit/buildd-tools/sbuild.git/

I've merged the multiarch-build patch into that version, as that's the
smallest delta from what is currently in use. So my main question is
is that the preferred version? I'm not quite sure why we are using
something based on 0.64.0 as that's not the stable version, nor is it
the testing version. But I presume that we generally want 'least
possible change' from what's in use so this seems like the right 
place to merge to.

It's not a big patch, as all the mechanism for 'add foreign arch' is
already in sbuild since it learned to cross-build a couple of years
ago. The patch just adds the foreign arch if there is an explicit
build-dep on it in the source (and that arch is not already configured
in the chroot). As discussed/described in
https://lists.debian.org/debian-devel-announce/2014/08/msg00013.html
section 3, especially 3.12

So, once I've tested this properly, is it OK to push this branch and
make a release for use on the buildds? What's the procedure for that
and who takes care of uploading to the special buildd-tools repo?

Do we have any special testing for the buildd branch beyond the normal
sbuild package tests?

BTW  I just noticed that the sources at
https://buildd.debian.org/apt/pool/wheezy/ are 5M per release, not
500K, because they each include a copy of the git repo, which seems wrong?

Wookey
-- 
Principal hats:  Linaro, Emdebian, Wookware, Balloonboard, ARM
http://wookware.org/