From c0b82ff2e5b696371de62e0f4fcbba61361fc6b2 Mon Sep 17 00:00:00 2001
From: =?UTF-8?q?Joel=20Sikstr=C3=B6m?= <jsikstro@openjdk.org>
Date: Mon, 10 Nov 2025 09:41:55 +0000
Subject: [PATCH] 8370843: Deprecate AlwaysActAsServerClassMachine and
 NeverActAsServerClassMachine

Reviewed-by: ayang, kvn
---
 src/hotspot/share/gc/shared/gc_globals.hpp |  4 +--
 src/hotspot/share/runtime/arguments.cpp    |  2 ++
 src/java.base/share/man/java.md            | 40 +++++++++++-----------
 3 files changed, 24 insertions(+), 22 deletions(-)

diff --git a/src/hotspot/share/gc/shared/gc_globals.hpp b/src/hotspot/share/gc/shared/gc_globals.hpp
index 4fb72f4102a..e86a8744847 100644
--- a/src/hotspot/share/gc/shared/gc_globals.hpp
+++ b/src/hotspot/share/gc/shared/gc_globals.hpp
@@ -263,10 +263,10 @@
           "before pushing a continuation entry")                            \
                                                                             \
   product_pd(bool, NeverActAsServerClassMachine,                            \
-          "Never act like a server-class machine")                          \
+          "(Deprecated) Never act like a server-class machine")             \
                                                                             \
   product(bool, AlwaysActAsServerClassMachine, false,                       \
-          "Always act like a server-class machine")                         \
+          "(Deprecated) Always act like a server-class machine")            \
                                                                             \
   product(uint64_t, MaxRAM, 0,                                              \
           "(Deprecated) Real memory size (in bytes) used to set maximum "   \
diff --git a/src/hotspot/share/runtime/arguments.cpp b/src/hotspot/share/runtime/arguments.cpp
index 730bb7871e2..79027cf113f 100644
--- a/src/hotspot/share/runtime/arguments.cpp
+++ b/src/hotspot/share/runtime/arguments.cpp
@@ -537,6 +537,8 @@ static SpecialFlag const special_jvm_flags[] = {
   { "PSChunkLargeArrays",           JDK_Version::jdk(26),  JDK_Version::jdk(27), JDK_Version::jdk(28) },
   { "MaxRAM",                       JDK_Version::jdk(26),  JDK_Version::jdk(27), JDK_Version::jdk(28) },
   { "AggressiveHeap",               JDK_Version::jdk(26),  JDK_Version::jdk(27), JDK_Version::jdk(28) },
+  { "NeverActAsServerClassMachine", JDK_Version::jdk(26),  JDK_Version::jdk(27), JDK_Version::jdk(28) },
+  { "AlwaysActAsServerClassMachine", JDK_Version::jdk(26),  JDK_Version::jdk(27), JDK_Version::jdk(28) },
   // --- Deprecated alias flags (see also aliased_jvm_flags) - sorted by obsolete_in then expired_in:
   { "CreateMinidumpOnCrash",        JDK_Version::jdk(9),  JDK_Version::undefined(), JDK_Version::undefined() },
 
diff --git a/src/java.base/share/man/java.md b/src/java.base/share/man/java.md
index 0f9d8e89bfc..43719ff619a 100644
--- a/src/java.base/share/man/java.md
+++ b/src/java.base/share/man/java.md
@@ -1235,26 +1235,6 @@ These `java` options control the runtime behavior of the Java HotSpot VM.
 
     This option is only supported on Linux with GNU C Library (glibc).
 
-`-XX:+NeverActAsServerClassMachine`
-:   Enable the "Client VM emulation" mode which only uses the C1 JIT compiler,
-    a 32Mb CodeCache and the Serial GC. The maximum amount of memory that the
-    JVM may use (controlled by the `-XX:MaxRAM=n` flag) is set to 1GB by default.
-    The string "emulated-client" is added to the JVM version string.
-
-    By default the flag is set to `true` only on Windows in 32-bit mode and
-    `false` in all other cases.
-
-    The "Client VM emulation" mode will not be enabled if any of the following
-    flags are used on the command line:
-
-    ```
-    -XX:{+|-}TieredCompilation
-    -XX:CompilationMode=mode
-    -XX:TieredStopAtLevel=n
-    -XX:{+|-}EnableJVMCI
-    -XX:{+|-}UseJVMCICompiler
-    ```
-
 `-XX:ObjectAlignmentInBytes=`*alignment*
 :   Sets the memory alignment of Java objects (in bytes). By default, the value
     is set to 8 bytes. The specified value should be a power of 2, and must be
@@ -2951,6 +2931,26 @@ they're used.
     the configuration of the computer (RAM and CPU). By default, the option
     is disabled and the heap sizes are configured less aggressively.
 
+`-XX:+NeverActAsServerClassMachine`
+:   Enable the "Client VM emulation" mode which only uses the C1 JIT compiler,
+    a 32Mb CodeCache and the Serial GC. The maximum amount of memory that the
+    JVM may use (controlled by the `-XX:MaxRAM=n` flag) is set to 1GB by default.
+    The string "emulated-client" is added to the JVM version string.
+
+    By default the flag is set to `true` only on Windows in 32-bit mode and
+    `false` in all other cases.
+
+    The "Client VM emulation" mode will not be enabled if any of the following
+    flags are used on the command line:
+
+    ```
+    -XX:{+|-}TieredCompilation
+    -XX:CompilationMode=mode
+    -XX:TieredStopAtLevel=n
+    -XX:{+|-}EnableJVMCI
+    -XX:{+|-}UseJVMCICompiler
+    ```
+
 ## Obsolete Java Options
 
 These `java` options are still accepted but ignored, and a warning is issued