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

[Roland McGrath 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
----------------
frobtech wrote:

All libc implementation code will use libc's internal APIs, which will never ossify.  All parts of libc's implementation will need to be maintained in the sense of continually modernizing with the rest of the libc implementation.  The pace of change of the common portions will eventually slow down, and the pace of change of any given target support implementation will slow as that target's details stabilize and support becomes complete.  So the amount of effort required of each target's maintainers will decrease and stabilize, but never reach zero.

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