[RFC] A change to the way packages are built

[David Lang]

On Wed, 4 May 2016, Daniel Dickinson wrote:

> Hi,
>
> I wanted to know if there is any appetite for an idea I've been kicking
> around in my head for a while for package builds.
>
> Basically one builds a minimal SDK and does kind of like Debian where a
> git commit to a package kicks of a build of pristine environment which
> builds only the package and it's dependencies.
>
> The goals are:
>
> 1) Avoid the cost of monolithic rebuilds of every package in the enabled
> feeds for every snapshot (obviously packages depend on specific kernel
> versions do have to be rebuilt when the kernel is rebuilt).
>
> 2) Faster turnaround on package builds when a package change is committed.
>
> 3) Decouple (where possible) packages from the core.
>
> Thoughts?

The problem I expect you to run into is dependencies between packages. You 
really want to have multiple stages

1. compile the package in isolation (avoid any "won't build" or "won't pass 
self-test" situations)

2. comile all the packages that depend on this package, see if their self-tests 
still work.

3. compile and test everything together to catch conflicts between package A and 
package B both making changes that end up conflicting when building package C.

automated tests for #1 would be a good start.

David Lang