diff --git a/lib/systems/architectures.nix b/lib/systems/architectures.nix
index 94127fa9..5253e4bb 100644
--- a/lib/systems/architectures.nix
+++ b/lib/systems/architectures.nix
@@ -32,9 +32,24 @@ rec {
     armv5te        = [ ];
     armv6          = [ ];
     armv7-a        = [ ];
-    armv8-a        = [ ];
+    armv8-a        = [ "fp" "simd" ];
+    "armv8.1-a"    = [ "crc" "lse" "rdma" ] ++ features.armv8-a;
+    "armv8.2-a"    = features."armv8.1-a";
+    "armv8.3-a"    = [ "pauth" ] ++ features."armv8.2-a";
+    "armv8.4-a"    = [ "flagm" "fp16fml" "dotprod" ] ++ features."armv8.3-a";
+    "armv8.5-a"    = [ "sb" "sbss" "predres" ] ++ features."armv8.4-a";
+    "armv8.6-a"    = [ "bf16" "i8mm" ] ++ features."armv8.5-a";
+    "armv8.7-a"    = [ "ls64" ] ++ features."armv8.6-a";
+    "armv8.8-a"    = [ "mops" ] ++ features."armv8.7-a";
+    "armv9-a"      = [ "sve" "sve2" ] ++ features."armv8.5-a";
+    "armv9.1-a"    = [ "bf16" "i8mm" ] ++ features."armv9-a";
+    "armv9.2-a"    = [ "ls64" ] ++ features."armv9.1-a";
+    "armv9.3-a"    = [ "mops" ] ++ features."armv9.2-a";
     mips32         = [ ];
     loongson2f     = [ ];
+    riscv64-g      = [ "multiply" "atomic" "float" "double" "csr" "ifencei" ];
+    riscv64-gc     = [ "compressed" ] ++ features.riscv64-g;
+    riscv64-gcv    = [ "vector" ] ++ features.riscv64-gc;
   };

   # a superior CPU has all the features of an inferior and is able to build and test code for it
@@ -85,8 +100,23 @@ rec {
     armv6          = [ ];
     armv7-a        = [ ];
     armv8-a        = [ ];
+    "armv8.1-a"    = [ "armv8-a" ] ++ inferiors.armv8-a;
+    "armv8.2-a"    = [ "armv8.1-a" ] ++ inferiors."armv8.1-a";
+    "armv8.3-a"    = [ "armv8.2-a" ] ++ inferiors."armv8.2-a";
+    "armv8.4-a"    = [ "armv8.3-a" ] ++ inferiors."armv8.3-a";
+    "armv8.5-a"    = [ "armv8.4-a" ] ++ inferiors."armv8.4-a";
+    "armv8.6-a"    = [ "armv8.5-a" ] ++ inferiors."armv8.5-a";
+    "armv8.7-a"    = [ "armv8.6-a" ] ++ inferiors."armv8.6-a";
+    "armv8.8-a"    = [ "armv8.7-a" ] ++ inferiors."armv8.7-a";
+    "armv9-a"      = [ "armv8.5-a" ] ++ inferiors."armv8.5-a";
+    "armv9.1-a"    = [ "armv9-a" "armv8.6-a" ] ++ inferiors."armv9-a" ++ inferiors."armv8.6-a";
+    "armv9.2-a"    = [ "armv9.1-a" "armv8.7-a" ] ++ inferiors."armv9.1-a" ++ inferiors."armv8.7-a";
+    "armv9.3-a"    = [ "armv9.2-a" "armv8.8-a" ] ++ inferiors."armv9.2-a" ++ inferiors."armv8.8-a";
     mips32         = [ ];
     loongson2f     = [ ];
+    riscv64-g      = [ ];
+    riscv64-gc     = [ "riscv64-g" ] ++ inferiors.riscv64-g;
+    riscv64-gcv    = [ "riscv64-gc" ] ++ inferiors.riscv64-gc;
   };

   predicates = let
diff --git a/pkgs/build-support/cc-wrapper/default.nix b/pkgs/build-support/cc-wrapper/default.nix
index e0ee3dae41f..49dbbe56594 100644
--- a/pkgs/build-support/cc-wrapper/default.nix
+++ b/pkgs/build-support/cc-wrapper/default.nix
@@ -122,6 +122,10 @@ let
         znver1         = versionAtLeast ccVersion "6.0";
         znver2         = versionAtLeast ccVersion "9.0";
         znver3         = versionAtLeast ccVersion "11.0";
+        # ARM
+        # TODO: Fill in as needed
+        # RISCV
+        # TODO: Fill in as needed
       }.${arch} or true
     else if isClang then
       { # Intel
@@ -132,6 +136,10 @@ let
         # AMD
         znver1         = versionAtLeast ccVersion "4.0";
         znver2         = versionAtLeast ccVersion "9.0";
+        # AMD
+        # TODO: Fill in as needed
+        # RISCV
+        # TODO: Fill in as needed
       }.${arch} or true
     else
       false;
diff --git a/pkgs/top-level/impure.nix b/pkgs/top-level/impure.nix
index 4d847e280f4..874b776c1e1 100644
--- a/pkgs/top-level/impure.nix
+++ b/pkgs/top-level/impure.nix
@@ -9,12 +9,15 @@ let
   # Return ‘x’ if it evaluates, or ‘def’ if it throws an exception.
   try = x: def: let res = builtins.tryEval x; in if res.success then res.value else def;

+  configuredLocalSystem = if builtins.pathExists "/etc/nix/local-system.json" then builtins.fromJSON (builtins.readFile "/etc/nix/local-system.json") else { system = builtins.currentSystem; };
+  localSystemOverriden = args: args ? system && (args.system != configuredLocalSystem);
+  defaultLocalSystem = args: if localSystemOverriden args then { system = args.system; } else configuredLocalSystem;
 in

 { # We put legacy `system` into `localSystem`, if `localSystem` was not passed.
   # If neither is passed, assume we are building packages on the current
   # (build, in GNU Autotools parlance) platform.
-  localSystem ? { system = args.system or builtins.currentSystem; }
+  localSystem ? null

 # These are needed only because nix's `--arg` command-line logic doesn't work
 # with unnamed parameters allowed by ...
@@ -78,6 +81,9 @@ in

 , ...
 } @ args:
+let
+  localSystem' = if localSystem == null then defaultLocalSystem args else localSystem;
+in

 # If `localSystem` was explicitly passed, legacy `system` should
 # not be passed, and vice-versa.
@@ -85,5 +91,6 @@ assert args ? localSystem -> !(args ? system);
 assert args ? system -> !(args ? localSystem);

 import ./. (builtins.removeAttrs args [ "system" ] // {
-  inherit config overlays localSystem;
+  inherit config overlays;
+  localSystem = localSystem';
 })