Rebase onto e4ad989506ec7d71f7302cc3067abd82730a4beb HEAD rootfs

Signed-off-by: Alyssa Ross <hi@alyssa.is>

2 files changed, 20 insertions, 2 deletions

diff --git a/doc/using/overlays.chapter.md b/doc/using/overlays.chapter.md
index 6ee52215a4e..1bec6586f28 100644
--- a/doc/using/overlays.chapter.md
+++ b/doc/using/overlays.chapter.md
@@ -77,7 +77,7 @@ In Nixpkgs, we have multiple implementations of the BLAS/LAPACK numerical linear
 
     The Nixpkgs attribute is `openblas` for ILP64 (integer width = 64 bits) and `openblasCompat` for LP64 (integer width = 32 bits).  `openblasCompat` is the default.
 
--   [LAPACK reference](http://www.netlib.org/lapack/) (also provides BLAS and CBLAS)
+-   [LAPACK reference](https://www.netlib.org/lapack/) (also provides BLAS and CBLAS)
 
     The Nixpkgs attribute is `lapack-reference`.
 
@@ -156,7 +156,7 @@ All programs that are built with [MPI](https://en.wikipedia.org/wiki/Message_Pas
 
 -   [MVAPICH](https://mvapich.cse.ohio-state.edu/), attribute name `mvapich`
 
-To provide MPI enabled applications that use `MPICH`, instead of the default `Open MPI`, simply use the following overlay:
+To provide MPI enabled applications that use `MPICH`, instead of the default `Open MPI`, use the following overlay:
 
 ```nix
 self: super:
diff --git a/doc/using/platform-support.chapter.md b/doc/using/platform-support.chapter.md
new file mode 100644
index 00000000000..3f91b3d5d98
--- /dev/null
+++ b/doc/using/platform-support.chapter.md
@@ -0,0 +1,18 @@
+# Platform Support {#chap-platform-support}
+
+Packages receive varying degrees of support, both in terms of maintainer attention and available computation resources for continuous integration (CI).
+
+Below is the list of the best supported platforms:
+
+- `x86_64-linux`: Highest level of support.
+- `aarch64-linux`: Well supported, with most packages building successfully in CI.
+- `aarch64-darwin`: Receives better support than `x86_64-darwin`.
+- `x86_64-darwin`: Receives some support.
+
+There are many other platforms with varying levels of support.
+The provisional platform list in [Appendix A] of [RFC046], while not up to date, can be used as guidance.
+
+A more formal definition of the platform support tiers is provided in [RFC046], but has not been fully implemented yet.
+
+[RFC046]: https://github.com/NixOS/rfcs/blob/master/rfcs/0046-platform-support-tiers.md
+[Appendix A]: https://github.com/NixOS/rfcs/blob/master/rfcs/0046-platform-support-tiers.md#appendix-a-non-normative-description-of-platforms-in-november-2019