Prefix: add stabilisation TODOs, changelog entry

Signed-off-by: Thilo Fromm <thilofromm@microsoft.com>

PREFIX.md

@@ -2,6 +2,18 @@
 
 **!!! NOTE: Prefix support in the Flatcar SDK is EXPERIMENTAL at this time !!!**
 
+## Path to stabilisation TODO list
+
+Before prefix build support are considered stable, the below must be implemented:
+1. Integrate `cb-bootstrap` with the Flatcar SDK.
+   Currently, `setup_prefix` uses cross-boss' `cb-bootstrap` to set up the prefix environment.
+   Bootstrapping must be fully integrated with the Flatcar SDK before prefix builds are considered stable.
+2. Integrate prefix builds with `/build/<board>` environment and use board cross toolchain.
+   Prefix builds currently use the SDK cross toolchains (`/usr/<arch>-gnu/`) instead of board toolchains in `/build/<board>`.
+   Prefix builds must be integrated with the board toolchains and stop using `cb-emerge` before considered stable.
+3. Add prefix wrappers for all portage tools (similar to board wrappers), not just `emerge`.
+4. Add test cases for prefix builds to [mantle/kola](https://github.com/flatcar/mantle/tree/flatcar-master/kola).
+
 ## About
 
 Prefix builds let you build and ship applications and all their dependencies in a custom directory.

changelog/changes/2023-09-20-experimental-prefix-builds.md

@@ -0,0 +1 @@
+- SDK: Experimental support for [prefix builds](https://github.com/flatcar/scripts/blob/main/PREFIX.md) to create distro independent, portable, self-contained applications w/ all dependencies included. With contributions from [chewi](https://github.com/chewi) and [HappyTobi](https://github.com/HappyTobi).