--- a/src/hotspot/share/runtime/arguments.cpp	Mon Oct 02 17:20:14 2017 +0300
+++ b/src/hotspot/share/runtime/arguments.cpp	Mon Oct 02 18:56:30 2017 -0400
@@ -377,6 +377,7 @@
   // --- Non-alias flags - sorted by obsolete_in then expired_in:
   { "MaxGCMinorPauseMillis",        JDK_Version::jdk(8), JDK_Version::undefined(), JDK_Version::undefined() },
   { "UseConcMarkSweepGC",           JDK_Version::jdk(9), JDK_Version::undefined(), JDK_Version::undefined() },
+  { "AssumeMP",                     JDK_Version::jdk(10),JDK_Version::undefined(), JDK_Version::undefined() },
   { "MonitorInUseLists",            JDK_Version::jdk(10),JDK_Version::undefined(), JDK_Version::undefined() },
   { "MaxRAMFraction",               JDK_Version::jdk(10),  JDK_Version::undefined(), JDK_Version::undefined() },
   { "MinRAMFraction",               JDK_Version::jdk(10),  JDK_Version::undefined(), JDK_Version::undefined() },
@@ -4476,16 +4477,6 @@
 
   set_shared_spaces_flags();
 
-#if defined(SPARC)
-  // BIS instructions require 'membar' instruction regardless of the number
-  // of CPUs because in virtualized/container environments which might use only 1
-  // CPU, BIS instructions may produce incorrect results.
-
-  if (FLAG_IS_DEFAULT(AssumeMP)) {
-    FLAG_SET_DEFAULT(AssumeMP, true);
-  }
-#endif
-
   // Check the GC selections again.
   if (!check_gc_consistency()) {
     return JNI_EINVAL;

--- a/src/hotspot/share/runtime/globals.hpp	Mon Oct 02 17:20:14 2017 +0300
+++ b/src/hotspot/share/runtime/globals.hpp	Mon Oct 02 18:56:30 2017 -0400
@@ -592,8 +592,8 @@
           range(8, 256)                                                     \
           constraint(ObjectAlignmentInBytesConstraintFunc,AtParse)          \
                                                                             \
-  product(bool, AssumeMP, false,                                            \
-          "Instruct the VM to assume multiple processors are available")    \
+  product(bool, AssumeMP, true,                                             \
+          "(Deprecated) Instruct the VM to assume multiple processors are available")\
                                                                             \
   /* UseMembar is theoretically a temp flag used for memory barrier      */ \
   /* removal testing.  It was supposed to be removed before FCS but has  */ \

--- a/src/hotspot/share/runtime/os.hpp	Mon Oct 02 17:20:14 2017 +0300
+++ b/src/hotspot/share/runtime/os.hpp	Mon Oct 02 18:56:30 2017 -0400
@@ -213,7 +213,7 @@
     // the bootstrap routine for the stub generator needs to check
     // the processor count directly and leave the bootstrap routine
     // in place until called after initialization has ocurred.
-    return (_processor_count != 1) || AssumeMP;
+    return AssumeMP || (_processor_count != 1);
   }
   static julong available_memory();
   static julong physical_memory();

--- a/test/hotspot/jtreg/runtime/CommandLine/VMDeprecatedOptions.java	Mon Oct 02 17:20:14 2017 +0300
+++ b/test/hotspot/jtreg/runtime/CommandLine/VMDeprecatedOptions.java	Mon Oct 02 18:56:30 2017 -0400
@@ -46,6 +46,7 @@
         {"MaxRAMFraction",            "8"},
         {"MinRAMFraction",            "2"},
         {"InitialRAMFraction",        "64"},
+        {"AssumeMP",                  "false"},
 
         // deprecated alias flags (see also aliased_jvm_flags):
         {"DefaultMaxRAMFraction", "4"},