Merge pull request #1055 from jonorossi/rdtsc-arm

Fix fatal SEHException on Arm calling RDTSC

Author: drewnoakes

src/NetMQ/Core/Utils/OpCode.cs

@@ -12,13 +12,21 @@ internal static class Opcode
 
         public static bool Open()
         {
+#if NETSTANDARD1_1_OR_GREATER || NET471_OR_GREATER
+            if (RuntimeInformation.ProcessArchitecture != Architecture.X86 &&
+                RuntimeInformation.ProcessArchitecture != Architecture.X64)
+            {
+                return false; // RDTSC instruction not supported
+            }
+#endif
+
             var p = (int)Environment.OSVersion.Platform;
 
             byte[] rdtscCode = IntPtr.Size == 4 ? RDTSC_32 : RDTSC_64;
 
             s_size = (ulong)(rdtscCode.Length);
 
-            if ((p == 4) || (p == 128))
+            if ((p == 4) || (p == 128)) // Unix || Mono on Unix
             {
                 // Unix
                 if (IsARMArchitecture()) return false;