Cross-building Debian packages and rebootstrap
==============================================

Introduction
------------

* Recent discussion in debian-cross ML:
  https://lists.debian.org/debian-cross/2018/06/msg00000.html

* Consideration
  * share the current development state of cross-building
  * clarify new issues to be solved
  * future plan of such kind of activities

Exchanging people's interests and priorities (Timed-limited)
------------------------------------------------------------

* Kazu:
  * 1. Make as many packages cross-buildable as possible
    * Priority: popcon + packages usually used in our products
    * Solving "missing perl-base, python*" related issues,
      because many packages are "unsatisfiable" in
      http://subdivi.de/~helmut/cross_report_20180614.html
  * 2. Sharing common ways to test cross-building
    * Tool: sbuild
    * How to setup build env (drop CONFIG_SITE, DEB_BUILD_*, --add-depends?)
    * Documentating
  * 3. Common build infrastructure in Debian community (cross-buildd)
    * Hardware sponsor for running a cross buildd?
    * Required H/W resources?
    * Developing and maintaining the tooling that can setup and do builds?
* zumbi:
  * "Cross-distro" support: cross building packages between different Linux
    distributions (e.g. cross build application to another distro such apertis
    or pureos)
* Helmut:
  * Enable building Debian from source (bootstrap, initially cross bootstrap)
  * cross building all of Debian exhibits toolchain problems and gives a better view of what build profiles are necessary
* ruinland?:
  * Improve docuementation/wiki pages
  * riscv64
* Kay Williams:
  * evaluating Debian as an operating system to build on
  * image building
* ?
  * cross building installation media
  * guix?

* ... Your interests and priorities

Discussion
----------

* Recent issues in debian-cross -> https://lists.debian.org/debian-cross/2018/06/msg00000.html
  * making more packages cross buildable?
  * make perl cross buildable?
  * cross translatable toolchain dependencies?
  * reduce toolchain bootstrap to two stages?
  * foreign image building without qemu?
  * ... your problems

* How to share efforts (i.e. patches, testing, investigation) for cross-building packages
  * debian-cross ML
  * Avoid duplications -> Use common user and user tag in BTS
    * user debian-cross@lists.debian.org usertags ftcbfs
    * user debian-cross@lists.debian.org usertags cross-satisfiability
    * user helmutg@debian.org usertags rebootstrap (for general cross/bootstrap bugs)
    * usertag:"ftcbfs" for bugs about cross building a package where Build-Depends
      are cross-installable, but the build fails.
    * usertag: "cross-satisfiability" for bugs about packages that fail to satisfy
      their cross Build-Depends or that cause other packages to fail
      dependency satisfaction.

* Infrastructure for cross-building packages
   * First step: Clarify how to setup cross-build environment and share
   * Fix the defaults in sbuild/pbuilder. Make --host/--host-arch just work.
   * Goal: cross-buildd?
   * Helmut's sbuild invocation:
     + sbuild
     + -d sid
     + --host=$arch
     + --profiles=nocheck,cross  # nocheck reduces dependencies, cross adds some. Maybe push into sbuild/pbuilder whenever --host is given?
     + --add-depends="libc-dev, libstdc++-dev"  # work around #815172, pbuilder does this automatically
     + --post-build-commands="home_grown_validator %SBUILD_CHANGES"  # extract .debs and fail if there are any build arch ELF objects. a sanity check. rarely triggers. equivalent to lintian tag binary-from-other-architecture
     + --chroot-setup-commands="install -D /dev/null /etc/dpkg-cross/cross-config.%SBUILD_HOST_ARCH"  # dpkg-cross' config.site is very broken
     + --debbuildopt=-J1 # readable build logs
     + --bd-uninstallable-explainer=apt # when building packages that dose thinks to be satisfiable, the dose (default) explainer is useless
     + --no-run-lintian # out of scope
     + --no-arch-all # should that be default when --host is given? used to be default
     + $pkg_$version

* Involving people who are interested in this topic
  * e.g. Add information in PTS (package tracking system) -> How?

* Documentating using Wiki to share information
  * Various pages of varying quality. How to organize/improve?
    * https://wiki.debian.org/CrossBuildPackagingGuidelines
    * https://wiki.debian.org/CrossCompiling
    * ...
  * Various pages on particular problem areas
    * https://wiki.debian.org/CrossTranslatableBuildDeps
    * https://wiki.debian.org/ReleaseGoals/CrossBuildableBase
    * https://wiki.debian.org/Teams/Ruby/CrossBuilding
    * ...

Fonzie(BnW.h): suggests installation images (or installing media) could be done the
[GNU Guix](https://www.gnu.org/software/guix/) way

* CI

Communication: irc #debian-bootstrap