https://git.musl-libc.org/cgit/musl/tree/arch/riscv32/bits?h=v1.2.5
https://git.musl-libc.org/cgit/musl/tree/arch/riscv64/bits?h=v1.2.5
https://git.musl-libc.org/cgit/musl/tree/arch/loongarch64/bits?h=v1.2.5

--- a/libphobos/libdruntime/core/stdc/fenv.d
+++ b/libphobos/libdruntime/core/stdc/fenv.d
@@ -443,6 +443,19 @@ else version (CRuntime_Musl)
         }
         alias ushort fexcept_t;
     }
+    else version(LoongArch64)
+    {
+        struct fenv_t
+        {
+            uint __cw;
+        }
+        alias uint fexcept_t;
+    }
+    else version (RISCV_Any)
+    {
+        alias uint fenv_t;
+        alias uint fexcept_t;
+    }
     else
     {
         static assert(false, "Architecture not supported.");
--- a/libphobos/libdruntime/core/sys/posix/signal.d
+++ b/libphobos/libdruntime/core/sys/posix/signal.d
@@ -2758,6 +2758,16 @@ else version (CRuntime_Musl)
         enum MINSIGSTKSZ = 2048;
         enum SIGSTKSZ    = 8192;
     }
+    else version (LoongArch64)
+    {
+        enum MINSIGSTKSZ = 4096;
+        enum SIGSTKSZ    = 16384;
+    }
+    else version (RISCV_Any)
+    {
+        enum MINSIGSTKSZ = 2048;
+        enum SIGSTKSZ    = 8192;
+    }
     else
         static assert(0, "unimplemented");
 
