| # Layer cake deprecation |
| |
| ## Goal & motivation |
| |
| Once upon a time Fuchsia OS & platform built out of multiple repositories, |
| designed in a cascade so that changes would flow from the lower-level |
| repositories to the higher-level repositories. This arrangement was called the |
| Layer Cake, and was comprised of four layers: Zircon (mostly kernel and |
| drivers), Garnet (low-level usermode services), Peridot (application-facing |
| services), and Topaz (application layer). |
| |
| The distinctions between layers weren't crystal clear, the cost/benefit of this |
| arrangement wasn't compelling, and so eventually we moved the majority of |
| Fuchsia OS & platform development into a single repository and established a |
| new [source code layout][source-code-layout]. |
| |
| However the old model left a lingering mark on our directory structure, as you |
| can still find top-level directories named after layers. |
| |
| These holdover-directories only serve to confuse new team members. |
| Let's move on. |
| |
| ## Technical background |
| |
| Not much to say here. Move slow and don't break things. |
| |
| Don't let them eat cake? |
| |
| ## How to help |
| |
| ### Picking a task |
| |
| The following directories remain in the Fuchsia git repository: |
| |
| * `//zircon/` |
| * `//garnet/` |
| |
| Show them that you mean business by picking one of their subdirectories and |
| moving it elsewhere - typically to `//src`. |
| |
| At the time of writing, prime targets for migrations include: |
| |
| * `//zircon/system/ulib/` |
| * `//zircon/system/utest/` |
| * `//garnet/bin/` |
| * `//garnet/lib/` |
| |
| ### Doing a task |
| |
| This mostly involves moving files and renaming some build targets. |
| 9 out of 10 changes will be entirely mechanical. |
| |
| ### Completing a task |
| |
| Find reviewers via OWNERS, merge your change, and take us one step closer to |
| deleting layer directories. |
| |
| In your commit messages, include: |
| |
| ```none |
| Bug: 36063 |
| ``` |
| |
| ## Examples |
| |
| * [`424156: [fuchsia-cprng] Move to src/lib/zircon/rust`](https://fuchsia-review.googlesource.com/c/fuchsia/+/424156) |
| * [`449714: [build][power] Move power_manager to //src/power`](https://fuchsia-review.googlesource.com/c/fuchsia/+/449714) |
| * [`461096: [thermd][shuffle] Migrate thermd from //garnet to //src`](https://fuchsia-review.googlesource.com/c/fuchsia/+/461096) |
| * [`473957: [sysmem] Move sysmem_connector to src/devices/sysmem/bin`](https://fuchsia-review.googlesource.com/c/fuchsia/+/473957) |
| * [`592547: [log_listener] Move from garnet to src/diagnostics`](https://fuchsia-review.googlesource.com/c/fuchsia/+/592547) |
| * [`627766: [boards][garnet] Cleanup graphics targets`](https://fuchsia-review.googlesource.com/c/fuchsia/+/627766) |
| |
| ## Sponsors |
| |
| Reach out for questions, status updates, or OWNERS approvals: |
| |
| * jamesr@google.com |
| * shayba@google.com |
| |
| [source-code-layout]: /docs/development/source_code/layout.md |
