lib.systems.examples: separate loongarch64 for desktop and embedded variants

lib/systems/examples.nix

@@ -170,9 +170,17 @@ rec {
     libc = "newlib";
   };
 
-  loongarch64-linux = {
+  # https://github.com/loongson/la-softdev-convention/blob/master/la-softdev-convention.adoc#10-operating-system-package-build-requirements
+  loongarch64-linux = lib.recursiveUpdate platforms.loongarch64-multiplatform {
     config = "loongarch64-unknown-linux-gnu";
   };
+  loongarch64-linux-embedded = lib.recursiveUpdate platforms.loongarch64-multiplatform {
+    config = "loongarch64-unknown-linux-gnu";
+    gcc = {
+      arch = "loongarch64";
+      strict-align = true;
+    };
+  };
 
   mmix = {
     config = "mmix-unknown-mmixware";

lib/systems/platforms.nix

@@ -572,6 +572,19 @@ rec {
     };
   };
 
+  loongarch64-multiplatform = {
+    gcc = {
+      # https://github.com/loongson/la-softdev-convention/blob/master/la-softdev-convention.adoc#10-operating-system-package-build-requirements
+      arch = "la64v1.0";
+      strict-align = false;
+      # Avoid text sections of large apps exceeding default code model
+      # Will be default behavior in LLVM 21 and hopefully GCC16
+      # https://github.com/loongson-community/discussions/issues/43
+      # https://github.com/llvm/llvm-project/pull/132173
+      cmodel = "medium";
+    };
+  };
+
   # This function takes a minimally-valid "platform" and returns an
   # attrset containing zero or more additional attrs which should be
   # included in the platform in order to further elaborate it.
@@ -607,6 +620,8 @@ rec {
     else if platform.parsed.cpu == lib.systems.parse.cpuTypes.powerpc64le then
       powernv
 
+    else if platform.isLoongArch64 then
+      loongarch64-multiplatform
     else
       { };
 }