[OE-core] RFC: Layer tooling brainstorming

[Andreas Mueller]

On Monday 18 April 2011 08:17:01 Richard Purdie wrote:
> Layer Tooling for OpenEmbedded
> ==============================
> 
> As we move forward with encouraging the use of metadata layers, a number
> of issues are appearing which imply the need for either infrastructure
> improvements to the layer construction, or better tools to handle the
> layers. The OS TSC discussed layers and layer tooling at the face to
> face TSC meeting in San Francisco. Some example problems that were
> identified that currently need addressing in some form are:
> 
> * There is no dependency information between layers (layer X depends on
>   layer Y and Z)
> * There is no version information present (layer X needs version A of
>   layer Y)
> * There is no layer "ABI" version number present in layers
> * Layer specific sanity checks? (other types of sanity checks on Yocto
>   1.1 roadmap)
> * Ability to fetch layers from other repositories
>   - Multi SCM?
>   - Use bitbake fetcher?
> * Ability to generate repositories representing composited layers (Poky,
>   RP has hacky scripts)
> * Tool to seperate patch into one for different composited parts
> * Ability to include partial components of repositories (e.g. only
>   beagleboard from meta-ti)
> * Tool to merge (flatten) several layers into one
> * Able to visualise dependencies between layers
> * When bitbake prints banner of branch/commit, need to cover all layer
>   components present
> * bitbake -e on steroids to highlight differences due to layer changes?
>   (long term goal)
> 
> Implementation thoughts:
> 
> * This layer tooling probably belongs at a higher level on the stack
>   than bitbake itself
> * Maybe need to split into "bootstrap" steps (e.g where pseduo is
>   established, layers downloaded etc)
> * Need some kind of config file defining layer's properties or at least
>   enhance layer.conf significantly
> * git submodules and repo should be looked at but due to specific needs
>   and ability to control tool evolution, likely need own tool.
> 
> This hopefully summarises the ideas we discussed in person, we therefore
> need to start looking at how to move forward from here with this but I
> wanted to document this for starters!
> 
> Cheers,
> 
> Richard
Afraid being killed I didn't dare to ask - but it's getting time to do so: What 
exactly are layers in OE and what are their advantages?

Andreas