Build system gripe session

Link available from the design-sessions session description page

Topics include:

• Moving "external" builds to a separate part of the tree, not built by default
• Adding more "external" builds; pvgrub for instance
• Making it easy to build with no internet access
• Using git submodules

Issues:

1. out of tree build not supported – shim build still half broken
2. Xen build re-evaluates compiler support for every translation unit. (Switch to newer Kconfig.)
3. meta virtualization build system (yocto) needs to pull simlink tricks, xen's build system stomp on that
4. containerize.sh is broken by symlink tricks in the build system
5. External projects get pulled in. Some think they should be removed, some think more should be added. Solved by raisin but nobody used it

For out-of-tree build, for xen, use Kbuild.

Would be nice to be able to do (without having to clean or fix or patch):

make CONFIG=release.config O=output/release
make CONFIG=shim.config O=output/shim

Different users have differnt requirements: developers, users, distro packagers.

For everyday users we should point people to their distros.

Raisin tried to be devstack, which is not developers want or trust.

People in favour of removing more stuff from xen.git. Should start with a document describing how to build a xen system – pull this tree, use this rune etc etc. Or use Android's build system?

Git runes in tree should disappear.

Need transitional plan for osstest.