[libc-commits] [libc] [libc][docs] Add a sunset policy to porting docs (PR #168936)

[Aaron Ballman via libc-commits]

================
@@ -103,3 +91,52 @@ bring up. The Linux config has ``headers.txt`` file listed separately for the
 config and the
 `x86_64 <https://github.com/llvm/llvm-project/tree/main/libc/config/linux/x86_64>`_
 config.
+
+
+Upstreaming
+===========
+
+Adding a target to the main LLVM-libc has some requirements to ensure that the
+targets stay in usable condition. LLVM-libc is under active development and
+without active maintenance targets will become stale and may be sunset.
+
+Maintenance
+-----------
+
+To add a target there must be one or more people whose responsibility it is to
+keep the target up to date or push it forwards if it's not complete. Those
+people are the maintainers, and they are responsible for keeping their target in
+good shape. This means fixing their target when it breaks, reviewing patches
+related to their target, and keeping the target's CI running.
+
+Maintainers are listed in libc/maintainers.rst and must follow
+`LLVM's maintainer policy <https://llvm.org/docs/DeveloperPolicy.html#maintainers>`_.
+
+CI builders
+-----------
+
+Every target needs at least one CI builder. These are used to check when the
+target breaks, and to help people who don't have access to the specific
+architecture fix their bugs. LLVM-libc has both presubmit CI on github
+and postsubmit CI on the `LLVM buildbot <https://lab.llvm.org/buildbot>`_. For
+instructions on contributing a postsubmit buildbot read
+`the LLVM documentation <https://llvm.org/docs/HowToAddABuilder.html>`_ and for
+presubmit tests read
+`the github documentation <https://github.com/llvm/llvm-project/blob/main/.github/workflows/libc-fullbuild-tests.yml>`
+TODO: proper link.
+
+The test configurations are at these links:
+ * `Linux Postsubmit <https://github.com/llvm/llvm-zorg/blob/main/zorg/buildbot/builders/annotated/libc-linux.py>`_
+ * `Windows Postsubmit <https://github.com/llvm/llvm-zorg/blob/main/zorg/buildbot/builders/annotated/libc-windows.py>`_
+ * `Fullbuild Presubmit <https://github.com/llvm/llvm-project/blob/main/.github/workflows/libc-fullbuild-tests.yml>`_
+ * `Overlay Presubmit <https://github.com/llvm/llvm-project/blob/main/.github/workflows/libc-overlay-tests.yml>`_
+
+Sunsetting
+----------
+
+If a target is incomplete and no progress has been made for 1 month, or if a
----------------
AaronBallman wrote:

One question I have about this policy though is: can a libc backend ever be "finished?" Given that the C committee puts out releases every 6-10 years, is it possible for a backend to be stable enough that it doesn't require any maintainers until a new standards release happens?

https://github.com/llvm/llvm-project/pull/168936