Package: apt Version: 0.8.14.1 Severity: Wishlist Now that multiarch is fully underway there is one significant component missing for cross-building to be nicely supported: resolving and installing cross-dependencies.
Essentially we want to be able to say apt-get install build-dep -a <arch> (the exact syntax is up to you guys, but I, Steve Langasek and mvogt thought that was reasonable) This page describes the extra aspects needed beyond the main multiarch spec to support cross-build-dependencies: https://wiki.ubuntu.com/MultiarchCross The core of this page is that the multiarch status of a package normally indicates whether the build arch or the cross arch version of a package will satisfy a build-dep. However it's not always correct, because whether a dep is 'native' or 'cross' is a property of the _depending_ package (only it knows whether it is running a binary or a linking a library in the depended-on package), and Multi-Arch status is a property of the depended-on package. So the page specifies build-dep modifiers which allow the depending package to say 'no I want something different from the default'. The table at the bottom of the wiki page shows how that works, and I give some metacode below for the logic (Which I think is right :-). We have copied the :any meaning from the multiarch spec for 'Depends', and added a :native The bottom of the page gives a table of which arch to install according to Multi-Arch state and build-dep modifiers. So the implementation work needed is 1) to parse build-dep modifiers separated by a ':' (as for the existing :any in Depends). These will ultimately include all architecture names, but currently we just allow :any and :native. 2) take a -a arch specifier to set the host arch for installing packages specified in build-deps. I don't believe APT::architecture is sufficient because setting that will cause APT::architecture (i.e. 'host') arch packages to be installed for currently-uninstalled M-A: foreign packages too, and we want build arch for those. We don't think this actually requires much work, as nearly everything is as existing logic (including all install-deps of any build-deps that get installed). The :any logic is the same as for Depends. So only the :native extra restriction is new. Here is a page which provides some useful test cases: https://wiki.linaro.org/Platform/DevPlatform/CrossCompile/CrossDependencyList It lists the declared build-deps of packages, and then which packages actually need to be installed for the build arch and which for the host arch. This should be useful for compiling test cases and checking whether a cross-dependency-satisfaction tool works. I hope all that makes sense, don't hesitate to ask if you have queries. 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
