Merge branch 'lukas/erts/deprecate-non-smp/OTP-14272'

* lukas/erts/deprecate-non-smp/OTP-14272:
  erts: Fix testcases for smp +S 1:1
  erts: Deprecate the non-smp emulators

8 files changed, 128 insertions, 72 deletions

diff --git a/erts/Makefile.in b/erts/Makefile
index 3052dc3065..3fe567b7d5 100644
--- a/erts/Makefile.in
+++ b/erts/Makefile
@@ -20,9 +20,9 @@
 
 .NOTPARALLEL:
 
-include $(ERL_TOP)/make/output.mk
 include $(ERL_TOP)/make/target.mk
 include vsn.mk
+include $(ERL_TOP)/make/$(TARGET)/otp.mk
 
 # ----------------------------------------------------------------------
 
@@ -33,10 +33,8 @@ ifeq ($(NO_START_SCRIPTS),)
 ERTSDIRS += start_scripts
 endif
 
-EXTRA_FLAVORS=smp
-
 .PHONY: all
-all: smp opt
+all: $(FLAVORS)
 
 .PHONY: docs
 docs:
@@ -56,9 +54,9 @@ debug opt clean:
 # - don't use them in scripts or assume they will always stay like this!
 #
 
-.PHONY: $(EXTRA_FLAVORS)
-$(EXTRA_FLAVORS):
-	$(V_at)( cd emulator && $(MAKE) opt FLAVOR=$@ )
+.PHONY: $(FLAVORS)
+$(FLAVORS):
+	$(V_at)( $(MAKE) opt FLAVOR=$@ )
 
 # Make erl script and erlc in $(ERL_TOP)/bin which runs the compiled version
 # Note that erlc is not a script and requires extra handling on cygwin.
@@ -129,7 +127,7 @@ makefiles:
 
 .PHONY: release
 release:
-	$(V_at)for f in plain $(EXTRA_FLAVORS) ; do \
+	$(V_at)for f in $(FLAVORS); do \
 		( cd emulator && $(MAKE) release FLAVOR=$$f ) \
 	done
 	$(V_at)for d in $(ERTSDIRS) $(XINSTDIRS); do \
diff --git a/erts/configure.in b/erts/configure.in
index b488ba9171..9ab5b4cfd2 100644
--- a/erts/configure.in
+++ b/erts/configure.in
@@ -154,6 +154,14 @@ AS_HELP_STRING([--disable-smp-support], [disable smp support]),
     *)  enable_smp_support=yes ;;
   esac ], enable_smp_support=unknown)
 
+AC_ARG_ENABLE(plain-emulator,
+AS_HELP_STRING([--enable-plain-emulator], [enable plain emulator])
+AS_HELP_STRING([--disable-plain-emulator], [disable plain emulator]),
+[ case "$enableval" in
+    no) enable_plain_emulator=no ;;
+    *)  enable_plain_emulator=yes ;;
+  esac ], enable_plain_emulator=unknown)
+
 AC_ARG_ENABLE(smp-require-native-atomics,
 	      AS_HELP_STRING([--disable-smp-require-native-atomics],
                              [disable the SMP requirement of a native atomic implementation]),
@@ -993,7 +1001,7 @@ else
     found_threads=yes
 fi
 
-
+FLAVORS=
 ERTS_BUILD_SMP_EMU=$enable_smp_support
 AC_MSG_CHECKING(whether an emulator with smp support should be built)
 case $ERTS_BUILD_SMP_EMU in
@@ -1078,6 +1086,9 @@ EOF
 
 if test $ERTS_BUILD_SMP_EMU = yes; then
 
+        DEFAULT_FLAVOR=smp
+        FLAVORS="$FLAVORS smp"
+
 	if test $found_threads = no; then
 	    AC_MSG_ERROR([cannot build smp enabled emulator since no thread library was found])
 	fi
@@ -1153,6 +1164,66 @@ fi
 
 AC_SUBST(ERTS_BUILD_SMP_EMU)
 
+ERTS_BUILD_PLAIN_EMU=$enable_plain_emulator
+AC_MSG_CHECKING(whether an emulator without smp support should be built)
+case $ERTS_BUILD_PLAIN_EMU in
+    yes)
+	AC_MSG_RESULT(yes; enabled by user)
+	;;
+    no)
+	AC_MSG_RESULT(no; disabled by user)
+	;;
+    unknown)
+        case "$enable_threads-$ERTS_BUILD_SMP_EMU" in
+            no-*)
+                ERTS_BUILD_PLAIN_EMU=yes
+                AC_MSG_RESULT(yes)
+                ;;
+            *-no)
+                ERTS_BUILD_PLAIN_EMU=yes
+                AC_MSG_RESULT(yes; enabled as smp emulator was disabled)
+                ;;
+            *)
+                ERTS_BUILD_PLAIN_EMU=no
+                AC_MSG_RESULT(no)
+                ;;
+        esac
+        ;;
+esac
+
+case $ERTS_BUILD_PLAIN_EMU in
+     yes)
+     	AC_DEFINE(ERTS_HAVE_PLAIN_EMU, 1, [Define if the non-smp emulator is built])
+        FLAVORS="$FLAVORS plain"
+        test -f "$ERL_TOP/erts/CONF_INFO" || echo "" > "$ERL_TOP/erts/CONF_INFO"
+        cat >> $ERL_TOP/erts/CONF_INFO <<EOF
+
+            The PLAIN aka NON-SMP emulator has been enabled.
+            This is a DEPRECATED feature scheduled for removal
+            in a future major release.
+
+EOF
+        ;;
+     no)
+        ;;
+esac
+
+AC_SUBST(ERTS_BUILD_PLAIN_EMU)
+AC_SUBST(FLAVORS)
+
+case "$ERTS_BUILD_PLAIN_EMU-$ERTS_BUILD_SMP_EMU" in
+     no-no)
+          AC_MSG_ERROR([both smp and non-smp emulators have been disabled, one of them has to be enabled])
+          ;;
+     *-no)
+          DEFAULT_FLAVOR=plain
+          ;;
+        *)
+          ;;
+esac
+
+AC_SUBST(DEFAULT_FLAVOR)
+
 AC_CHECK_FUNCS([posix_fadvise closefrom])
 AC_CHECK_HEADERS([linux/falloc.h])
 dnl * Old glibcs have broken fallocate64(). Make sure not to use it.
@@ -4953,7 +5024,6 @@ AC_CONFIG_FILES([
   include/internal/$host/ethread.mk:include/internal/ethread.mk.in
   include/internal/$host/erts_internal.mk:include/internal/erts_internal.mk.in
   lib_src/$host/Makefile:lib_src/Makefile.in
-  Makefile:Makefile.in
   ../make/$host/otp.mk:../make/otp.mk.in
   ../make/$host/otp_ded.mk:../make/otp_ded.mk.in
 ])
diff --git a/erts/doc/src/erl.xml b/erts/doc/src/erl.xml
index 29fef7348b..829acd1154 100644
--- a/erts/doc/src/erl.xml
+++ b/erts/doc/src/erl.xml
@@ -513,11 +513,11 @@
 	  system with SMP support is available. <c>-smp auto</c> starts
 	  the Erlang runtime system with SMP support enabled if it is
 	  available and more than one logical processor is detected.
-	  <c>-smp disable</c> starts a runtime system without SMP support.</p>
+	  <c>-smp disable</c> starts a runtime system without SMP support.
+           The runtime system without SMP support is deprecated and will
+           be removed in a future major release.</p>
         <note>
-          <p>The runtime system with SMP support is not available on all
-            supported platforms. See also flag
-            <seealso marker="#+S"><c>+S</c></seealso>.</p>
+          <p>See also flag<seealso marker="#+S"><c>+S</c></seealso>.</p>
         </note>
       </item>
       <tag><c><![CDATA[-version]]></c> (emulator flag)</tag>
diff --git a/erts/emulator/Makefile.in b/erts/emulator/Makefile.in
index 7ea0111e59..227aabcf1e 100644
--- a/erts/emulator/Makefile.in
+++ b/erts/emulator/Makefile.in
@@ -175,7 +175,23 @@ endif
 # NOTE: When adding a new type update ERL_BUILD_TYPE_MARKER in sys/unix/sys.c
 #
 
-ifeq ($(FLAVOR),smp)
+FLAVOR=$(DEFAULT_FLAVOR)
+
+ifeq ($(FLAVOR),plain)
+
+DS_SUPPORT=no
+DS_TEST=no
+
+FLAVOR_MARKER=
+FLAVOR_FLAGS=
+ENABLE_ALLOC_TYPE_VARS += nofrag
+M4FLAGS +=
+
+else # FLAVOR
+
+# If flavor isn't one of the above, it *is* smp flavor...
+override FLAVOR=smp
+
 FLAVOR_MARKER=.smp
 FLAVOR_FLAGS=-DERTS_SMP
 ENABLE_ALLOC_TYPE_VARS += smp nofrag
@@ -196,30 +212,15 @@ DS_SUPPORT=no
 DS_TEST=no
 endif # DIRTY_SCHEDULER_SUPPORT
 
-else # FLAVOR
-
-DS_SUPPORT=no
-DS_TEST=no
-
-# If flavor isn't one of the above, it *is* plain flavor...
-override FLAVOR=plain
-FLAVOR_MARKER=
-FLAVOR_FLAGS=
-ENABLE_ALLOC_TYPE_VARS += nofrag
-M4FLAGS +=
-endif
+endif # FLAVOR
 
 TF_MARKER=$(TYPEMARKER)$(FLAVOR_MARKER)
 
-ifeq ($(FLAVOR)-@ERTS_BUILD_SMP_EMU@,smp-no)
-VOID_EMULATOR = '*** SMP emulator disabled by configure'
-else
 ifeq ($(TYPE)-@HAVE_VALGRIND@,valgrind-no)
 VOID_EMULATOR = '*** valgrind emulator disabled by configure'
 else
 VOID_EMULATOR =
 endif
-endif
 
 OPSYS=@OPSYS@
 sol2CFLAGS=
diff --git a/erts/emulator/test/scheduler_SUITE.erl b/erts/emulator/test/scheduler_SUITE.erl
index 885298ce34..64e51e7d7c 100644
--- a/erts/emulator/test/scheduler_SUITE.erl
+++ b/erts/emulator/test/scheduler_SUITE.erl
@@ -1087,12 +1087,8 @@ scheduler_threads(Config) when is_list(Config) ->
     {Sched, SchedOnln, _} = get_sstate(Config, ""),
     %% Configure half the number of both the scheduler threads and
     %% the scheduler threads online.
-    {HalfSched, HalfSchedOnln} = case SmpSupport of
-                                     false -> {1,1};
-                                     true ->
-                                         {Sched div 2,
-                                          SchedOnln div 2}
-                                 end,
+    {HalfSched, HalfSchedOnln} = {lists:max([1,Sched div 2]),
+                                  lists:max([1,SchedOnln div 2])},
     {HalfSched, HalfSchedOnln, _} = get_sstate(Config, "+SP 50:50"),
     %% Use +S to configure 4x the number of scheduler threads and
     %% 4x the number of scheduler threads online, but alter that
@@ -1149,12 +1145,8 @@ dirty_scheduler_threads(Config) when is_list(Config) ->
 dirty_scheduler_threads_test(Config) ->
     SmpSupport = erlang:system_info(smp_support),
     {Sched, SchedOnln, _} = get_dsstate(Config, ""),
-    {HalfSched, HalfSchedOnln} = case SmpSupport of
-                                     false -> {1,1};
-                                     true ->
-                                         {Sched div 2,
-                                          SchedOnln div 2}
-                                 end,
+    {HalfSched, HalfSchedOnln} = {lists:max([1,Sched div 2]),
+                                  lists:max([1,SchedOnln div 2])},
     Cmd1 = "+SDcpu "++integer_to_list(HalfSched)++":"++
 	integer_to_list(HalfSchedOnln),
     {HalfSched, HalfSchedOnln, _} = get_dsstate(Config, Cmd1),
diff --git a/erts/emulator/test/smoke_test_SUITE.erl b/erts/emulator/test/smoke_test_SUITE.erl
index 5eccdc562b..45b28b28a5 100644
--- a/erts/emulator/test/smoke_test_SUITE.erl
+++ b/erts/emulator/test/smoke_test_SUITE.erl
@@ -66,17 +66,10 @@ boot_combo(Config) when is_list(Config) ->
 			  ok
 		  end
 	  end,
-    SMPDisable = fun () -> false = erlang:system_info(smp_support) end,
     try
 	chk_boot(Config, "+Ktrue", NOOP),
 	chk_boot(Config, "+A42", A42),
-	chk_boot(Config, "-smp disable", SMPDisable),
 	chk_boot(Config, "+Ktrue +A42", A42),
-	chk_boot(Config, "-smp disable +A42",
-		 fun () -> SMPDisable(), A42() end),
-	chk_boot(Config, "-smp disable +Ktrue", SMPDisable),
-	chk_boot(Config, "-smp disable +Ktrue +A42",
-		 fun () -> SMPDisable(), A42() end),
 	%% A lot more combos could be implemented...
 	ok
     after
diff --git a/erts/emulator/test/statistics_SUITE.erl b/erts/emulator/test/statistics_SUITE.erl
index f51244485b..729e86cb4f 100644
--- a/erts/emulator/test/statistics_SUITE.erl
+++ b/erts/emulator/test/statistics_SUITE.erl
@@ -329,9 +329,9 @@ scheduler_wall_time_test(Type) ->
         %% 50% load
         HalfHogs = [StartHog() || _ <- lists:seq(1, (Schedulers-1) div 2)],
         HalfDirtyCPUHogs = [StartDirtyHog(dirty_cpu)
-                            || _ <- lists:seq(1, DirtyCPUSchedulers div 2)],
+                            || _ <- lists:seq(1, lists:max([1,DirtyCPUSchedulers div 2]))],
         HalfDirtyIOHogs = [StartDirtyHog(dirty_io)
-                           || _ <- lists:seq(1, DirtyIOSchedulers div 2)],
+                           || _ <- lists:seq(1, lists:max([1,DirtyIOSchedulers div 2]))],
         HalfLoad = lists:sum(get_load(Type)) div TotLoadSchedulers,
         if Schedulers < 2, HalfLoad > 80 -> ok; %% Ok only one scheduler online and one hog
            %% We want roughly 50% load
diff --git a/erts/etc/common/erlexec.c b/erts/etc/common/erlexec.c
index ee59759940..b29190e4d9 100644
--- a/erts/etc/common/erlexec.c
+++ b/erts/etc/common/erlexec.c
@@ -203,8 +203,8 @@ void error(char* format, ...);
  * Local functions.
  */
 
-#if !defined(ERTS_HAVE_SMP_EMU)
-static void usage_notsup(const char *switchname);
+#if !defined(ERTS_HAVE_SMP_EMU) || !defined(ERTS_HAVE_PLAIN_EMU)
+static void usage_notsup(const char *switchname, const char *alt);
 #endif
 static char **build_args_from_env(char *env_var);
 static char **build_args_from_string(char *env_var);
@@ -487,8 +487,7 @@ int main(int argc, char **argv)
     cpuinfo = erts_cpu_info_create();
     /* '-smp auto' is default */ 
 #ifdef ERTS_HAVE_SMP_EMU
-    if (erts_get_cpu_configured(cpuinfo) > 1)
-	emu_type |= EMU_TYPE_SMP;
+    emu_type |= EMU_TYPE_SMP;
 #endif
 
 #if defined(__WIN32__) && defined(WIN32_ALWAYS_DEBUG)
@@ -520,12 +519,11 @@ int main(int argc, char **argv)
 		    i++;
 		smp_auto:
 		    emu_type_passed |= EMU_TYPE_SMP;
-#ifdef ERTS_HAVE_SMP_EMU
-		    if (erts_get_cpu_configured(cpuinfo) > 1)
-			emu_type |= EMU_TYPE_SMP;
-		    else
+#if defined(ERTS_HAVE_PLAIN_EMU) && !defined(ERTS_HAVE_SMP_EMU)
+                    emu_type &= ~EMU_TYPE_SMP;
+#else
+                    emu_type |= EMU_TYPE_SMP;
 #endif
-			emu_type &= ~EMU_TYPE_SMP;
 		}
 		else if (strcmp(argv[i+1], "enable") == 0) {
 		    i++;
@@ -534,14 +532,18 @@ int main(int argc, char **argv)
 #ifdef ERTS_HAVE_SMP_EMU
 		    emu_type |= EMU_TYPE_SMP;
 #else
-		    usage_notsup("-smp enable");
+		    usage_notsup("-smp enable", "");
 #endif
 		}
 		else if (strcmp(argv[i+1], "disable") == 0) {
 		    i++;
 		smp_disable:
-		    emu_type_passed |= EMU_TYPE_SMP;
+		    emu_type_passed &= ~EMU_TYPE_SMP;
+#ifdef ERTS_HAVE_PLAIN_EMU
 		    emu_type &= ~EMU_TYPE_SMP;
+#else
+                    usage_notsup("-smp disable", " Use \"+S 1\" instead.");
+#endif
 		}
 		else {
 		smp:
@@ -550,7 +552,7 @@ int main(int argc, char **argv)
 #ifdef ERTS_HAVE_SMP_EMU
 		    emu_type |= EMU_TYPE_SMP;
 #else
-		    usage_notsup("-smp");
+		    usage_notsup("-smp", "");
 #endif
 		}
 	    } else if (strcmp(argv[i], "-smpenable") == 0) {
@@ -1183,14 +1185,14 @@ usage_aux(void)
 #ifdef __WIN32__
 	  "[-start_erl [datafile]] "
 #endif
-	  "[-smp "
+	  "[-smp [auto"
 #ifdef ERTS_HAVE_SMP_EMU
-	  "[enable|"
+	  "|enable"
 #endif
-	  "auto|disable"
-#ifdef ERTS_HAVE_SMP_EMU
-	  "]"
+#ifdef ERTS_HAVE_PLAIN_EMU
+	  "|disable"
 #endif
+	  "]"
 	  "] "
 	  "[-make] [-man [manopts] MANPAGE] [-x] [-emu_args] [-start_epmd BOOLEAN] "
 	  "[-args_file FILENAME] [+A THREADS] [+a SIZE] [+B[c|d|i]] [+c [BOOLEAN]] "
@@ -1212,11 +1214,11 @@ usage(const char *switchname)
     usage_aux();
 }
 
-#if !defined(ERTS_HAVE_SMP_EMU)
+#if !defined(ERTS_HAVE_SMP_EMU) || !defined(ERTS_HAVE_PLAIN_EMU)
 static void
-usage_notsup(const char *switchname)
+usage_notsup(const char *switchname, const char *alt)
 {
-    fprintf(stderr, "Argument \'%s\' not supported.\n", switchname);
+    fprintf(stderr, "Argument \'%s\' not supported.%s\n", switchname, alt);
     usage_aux();
 }
 #endif