I'm looking at adding multiarch-style cross-building support to sbuild. I've taken the work done in this bugrep so far (thanks to hector and Roger for that), which essentially makes sbuild BUILD/HOST aware andd the xapt resolver, and moved that forward to the current 0.62.5 sbuild release.
However, the procedure for multiarch crossbuilding is not the same as for xapt+dpkg-cross, so we need some slightly different changes. Essentially what needs to happen is: 0) get a chroot containing the usual build-essential stuff 1) Install cross-tools. (A build-essential-$arch package would be useful for this, to gloss over variations between distros and changes over time, but in the meantime we know what want and can add the packages to the config in $core-depends) this means: g++-arm-linux-gnueabi libc6-dev-armel-cross 1b) ensure that arm-linux-gnueabi-pkg-config wrapper link exists (will come with toolchain if toolchain is new enough) 1c) Add qemu-static support to chroot. Best done by schroot? 2) Configure dpkg for multiarch: add foreign-architecture armel to /etc/dpkg/dpkg.cfg.d/multiarch 3) configure a $arch source for apt: in /etc/apt/sources.list.d/foo deb [arch=armel] http://ports.ubuntu.com/ubuntu-ports oneiric main universe 4) to resolve the dependencies we need to run apt-get build-dep -aarmel $package instead of apt-get build-dep $package 5) Do the build by setting some environment variables: 'CONFIG_SITE' => '/etc/dpkg-cross/cross-config.$host_arch' 'DEB_BUILD_OPTIONS' => 'nocheck' 'DH_VERBOSE' => '1' (easily done by setting $build_environment in config) and run dpkg-buildpackage -aarmel So, all of this is straightforward in principle, but I'm not familiar with sbuild internals so it's not clear to me what the best method might be in each case. 1) seems easy enough. Add needed packages to add-depends. To write a generic config needs some way to set $DEB_HOST_GNU_TYPE in the config file. Does such functionaility exist already? We have $host_arc, which could be set to 'armel', but then somewhere we need to do DEB_HOST_GNU_TYPE ?= $(shell dpkg-architecture -qDEB_HOST_GNU_TYPE -a$host_arch to get arm-linux-gnueabi. Does sbuild do any of this already? If not where might be a good place? 1b) needs a little script to be run. Along the lines of if [ ! -L /usr/bin/${host_triplet}-pkg-config ]; then ln -s /usr/share/pkg-config-crosswrapper ${host_triplet}pkg-config fi We have chroot-setup-commands which can presumably run any command which already exists in the chroot, but doesn't look like it lends itself to little scripts like that, so the chroot would have to be pre-populated with a suitable script? Same considerations apply to 2 and 3. chroot-setup-commands and pre-build-commands don't look like they support commands of the form echo foo > file Can these scripts be supplied by sbuild (in the same way that pbuilder hook-scripts are), or do they need to come from somewhere else? If the latter can they be in a package specified by add-depends or do those get pulled in too late? 4) I thought this would be a simple matter of adding -a$host_arch in lib/Sbuild/AptResolver.pm but it doesn't run apt-get build-dep directly, it just installs sbuild-build-depends-foo-dummy which has been prepared elsewhere. ResolverBase seems to generate this but nowhere does apt-get build-dep seem to get run so I'm not quite sure where to go poking. Clues welcome. 5) I think this can be done by just adding $debbuildopt = '-a$host_arch' to the config should if there is a better way. I'm happy to go prodding about but if there are obvious 'right ways' to do these things then direction is very welcome. Wookey -- Principal hats: Linaro, Emdebian, Wookware, Balloonboard, ARM http://wookware.org/ -- To UNSUBSCRIBE, email to debian-bugs-dist-requ...@lists.debian.org with a subject of "unsubscribe". Trouble? Contact listmas...@lists.debian.org
