diff -urN ruby-2.1.3.orig/ext/tk/extconf.rb ruby-2.1.3.for-SEGV-only/ext/tk/extconf.rb
--- ruby-2.1.3.orig/ext/tk/extconf.rb	2013-11-30 11:46:47.000000000 +0900
+++ ruby-2.1.3.for-SEGV-only/ext/tk/extconf.rb	2014-10-19 17:50:33.045820645 +0900
@@ -9,10 +9,10 @@
   # %w[8.9 8.8 8.7 8.6 8.5 8.4 8.3 8.2 8.1 8.0 7.6 4.2]
   # %w[8.7 8.6 8.5 8.4 8.3 8.2 8.1 8.0]
   # %w[8.7 8.6 8.5 8.4 8.0] # to shorten search steps
-  %w[8.5 8.4] # At present, Tcl/Tk8.6 is not supported.
+  %w[8.6 8.5 8.4]
 
 TkLib_Config['unsupported_versions'] =
-  %w[8.8 8.7 8.6] # At present, Tcl/Tk8.6 is not supported.
+  %w[8.8 8.7]
 
 TkLib_Config['major_nums'] = '87'
 
diff -urN ruby-2.1.3.orig/ext/tk/lib/tk.rb ruby-2.1.3.for-SEGV-only/ext/tk/lib/tk.rb
--- ruby-2.1.3.orig/ext/tk/lib/tk.rb	2011-05-27 08:36:33.000000000 +0900
+++ ruby-2.1.3.for-SEGV-only/ext/tk/lib/tk.rb	2014-10-24 02:59:04.482665787 +0900
@@ -1309,8 +1309,12 @@
           end
 
           unless interp.deleted?
-            #Thread.current[:status].value = TclTkLib.mainloop(false)
-            Thread.current[:status].value = interp.mainloop(false)
+            begin
+              #Thread.current[:status].value = TclTkLib.mainloop(false)
+              Thread.current[:status].value = interp.mainloop(false)
+            rescue Exception=>e
+              puts "ignore exception on interp: #{e.inspect}\n" if $DEBUG
+            end
           end
 
         ensure
@@ -1569,7 +1573,15 @@
   EOL
 =end
 
-  at_exit{ INTERP.remove_tk_procs(TclTkLib::FINALIZE_PROC_NAME) }
+  if !WITH_RUBY_VM || RUN_EVENTLOOP_ON_MAIN_THREAD ### check Ruby 1.9 !!!!!!!
+    at_exit{ INTERP.remove_tk_procs(TclTkLib::FINALIZE_PROC_NAME) }
+  else
+    at_exit{
+      Tk.root.destroy
+      INTERP.remove_tk_procs(TclTkLib::FINALIZE_PROC_NAME)
+      INTERP_THREAD.kill.join
+    }
+  end
 
   EventFlag = TclTkLib::EventFlag
 
diff -urN ruby-2.1.3.orig/ext/tk/tcltklib.c ruby-2.1.3.for-SEGV-only/ext/tk/tcltklib.c
--- ruby-2.1.3.orig/ext/tk/tcltklib.c	2014-02-10 20:45:14.000000000 +0900
+++ ruby-2.1.3.for-SEGV-only/ext/tk/tcltklib.c	2014-10-19 19:17:00.014057636 +0900
@@ -6012,7 +6012,12 @@
     Tcl_CmdInfo info;
     int ret;
 
+    DUMP1("call ip_rbNamespaceObjCmd");
+    DUMP2("objc = %d", objc);
+    DUMP2("objv[0] = '%s'", Tcl_GetString(objv[0]));
+    DUMP2("objv[1] = '%s'", Tcl_GetString(objv[1]));
     if (!Tcl_GetCommandInfo(interp, "__orig_namespace_command__", &(info))) {
+        DUMP1("fail to get __orig_namespace_command__");
         Tcl_ResetResult(interp);
         Tcl_AppendResult(interp,
                          "invalid command name \"namespace\"", (char*)NULL);
@@ -6020,15 +6025,38 @@
     }
 
     rbtk_eventloop_depth++;
-    /* DUMP2("namespace wrapper enter depth == %d", rbtk_eventloop_depth); */
+    DUMP2("namespace wrapper enter depth == %d", rbtk_eventloop_depth);
 
     if (info.isNativeObjectProc) {
+#if TCL_MAJOR_VERSION == 8 && TCL_MINOR_VERSION < 6
+        DUMP1("call a native-object-proc");
         ret = (*(info.objProc))(info.objClientData, interp, objc, objv);
+#else
+        /* Tcl8.6 or later */
+        int i;
+        Tcl_Obj **cp_objv;
+        char org_ns_cmd_name[] = "__orig_namespace_command__";
+
+        DUMP1("call a native-object-proc for tcl8.6 or later");
+        cp_objv = RbTk_ALLOC_N(Tcl_Obj *, (objc + 1));
+
+        cp_objv[0] = Tcl_NewStringObj(org_ns_cmd_name, strlen(org_ns_cmd_name));
+        for(i = 1; i < objc; i++) {
+            cp_objv[i] = objv[i];
+        }
+        cp_objv[objc] = (Tcl_Obj *)NULL;
+
+        /* ret = Tcl_EvalObjv(interp, objc, cp_objv, TCL_EVAL_DIRECT); */
+        ret = Tcl_EvalObjv(interp, objc, cp_objv, 0);
+
+        ckfree((char*)cp_objv);
+#endif
     } else {
         /* string interface */
         int i;
         char **argv;
 
+        DUMP1("call with the string-interface");
         /* argv = (char **)Tcl_Alloc(sizeof(char *) * (objc + 1)); */
         argv = RbTk_ALLOC_N(char *, (objc + 1));
 #if 0 /* use Tcl_Preserve/Release */
@@ -6056,9 +6084,10 @@
 #endif
     }
 
-    /* DUMP2("namespace wrapper exit depth == %d", rbtk_eventloop_depth); */
+    DUMP2("namespace wrapper exit depth == %d", rbtk_eventloop_depth);
     rbtk_eventloop_depth--;
 
+    DUMP1("end of ip_rbNamespaceObjCmd");
     return ret;
 }
 #endif
@@ -6068,6 +6097,8 @@
     Tcl_Interp *interp;
 {
 #if TCL_MAJOR_VERSION >= 8
+
+#if TCL_MAJOR_VERSION == 8 && TCL_MINOR_VERSION < 6
     Tcl_CmdInfo orig_info;
 
     if (!Tcl_GetCommandInfo(interp, "namespace", &(orig_info))) {
@@ -6084,6 +6115,11 @@
                           orig_info.deleteProc);
     }
 
+#else /* tcl8.6 or later */
+    Tcl_GlobalEval(interp, "rename namespace __orig_namespace_command__");
+
+#endif
+
     Tcl_CreateObjCommand(interp, "namespace", ip_rbNamespaceObjCmd,
                          (ClientData) 0, (Tcl_CmdDeleteProc *)NULL);
 #endif
@@ -8448,15 +8484,28 @@
 #endif
 {
     struct invoke_info *inf = (struct invoke_info *)arg;
+
+#if TCL_MAJOR_VERSION >= 8 && TCL_MINOR_VERSION < 6
     int i, len;
-#if TCL_MAJOR_VERSION >= 8
     int argc = inf->objc;
     char **argv = (char **)NULL;
 #endif
 
+    DUMP1("call invoke_tcl_proc");
+
+#if TCL_MAJOR_VERSION > 8 || (TCL_MAJOR_VERSION == 8 && TCL_MINOR_VERSION >= 6)
+
+    /* eval */
+    inf->ptr->return_value = Tcl_EvalObjv(inf->ptr->ip, inf->objc, inf->objv, TCL_EVAL_DIRECT);
+    /* inf->ptr->return_value = Tcl_EvalObjv(inf->ptr->ip, inf->objc, inf->objv, 0); */
+
+#else /* Tcl/Tk 7.x, 8.0 -- 8.5 */
+
     /* memory allocation for arguments of this command */
-#if TCL_MAJOR_VERSION >= 8
+#if TCL_MAJOR_VERSION == 8
+    /* Tcl/Tk 8.0 -- 8.5 */
     if (!inf->cmdinfo.isNativeObjectProc) {
+        DUMP1("called proc is not a native-obj-proc");
         /* string interface */
         /* argv = (char **)ALLOC_N(char *, argc+1);*/ /* XXXXXXXXXX */
         argv = RbTk_ALLOC_N(char *, (argc+1));
@@ -8470,11 +8519,14 @@
     }
 #endif
 
+    DUMP1("reset result of tcl-interp");
     Tcl_ResetResult(inf->ptr->ip);
 
     /* Invoke the C procedure */
-#if TCL_MAJOR_VERSION >= 8
+#if TCL_MAJOR_VERSION == 8
+    /* Tcl/Tk 8.0 -- 8.5 */
     if (inf->cmdinfo.isNativeObjectProc) {
+        DUMP1("call tcl_proc as a native-obj-proc");
         inf->ptr->return_value
             = (*(inf->cmdinfo.objProc))(inf->cmdinfo.objClientData,
                                         inf->ptr->ip, inf->objc, inf->objv);
@@ -8482,7 +8534,9 @@
     else
 #endif
     {
-#if TCL_MAJOR_VERSION >= 8
+#if TCL_MAJOR_VERSION == 8
+        /* Tcl/Tk 8.0 -- 8.5 */
+        DUMP1("call tcl_proc as not a native-obj-proc");
         inf->ptr->return_value
             = (*(inf->cmdinfo.proc))(inf->cmdinfo.clientData, inf->ptr->ip,
                                      argc, (CONST84 char **)argv);
@@ -8505,6 +8559,9 @@
 #endif
     }
 
+#endif /* Tcl/Tk 8.6 or later || Tcl 7.x, 8.0 -- 8.5 */
+
+    DUMP1("end of invoke_tcl_proc");
     return Qnil;
 }
 
@@ -8644,7 +8701,9 @@
 #endif
 
     /* invoke tcl-proc */
+    DUMP1("invoke tcl-proc");
     rb_protect(invoke_tcl_proc, (VALUE)&inf, &status);
+    DUMP2("status of tcl-proc, %d", status);
     switch(status) {
     case TAG_RAISE:
         if (NIL_P(rb_errinfo())) {