From 1069ccebcc32e02055985e2babfa2986a2e295ca Mon Sep 17 00:00:00 2001
From: Thomas Devoogdt <thomas@devoogdt.com>
Date: Wed, 4 Feb 2026 06:48:59 +0000
Subject: [PATCH] 8376684: Compile OpenJDK in headless mode without required
 X11 libraries

Reviewed-by: erikj, aivanov
---
 doc/building.html                                |  7 +++----
 doc/building.md                                  |  6 ++----
 make/autoconf/libraries.m4                       |  8 ++++----
 make/modules/java.desktop/lib/AwtLibraries.gmk   | 16 ++++++++++++++--
 .../unix/native/common/awt/utility/rect.h        |  4 ++--
 5 files changed, 25 insertions(+), 16 deletions(-)

diff --git a/doc/building.html b/doc/building.html
index 8e5a7625371..534888ef667 100644
--- a/doc/building.html
+++ b/doc/building.html
@@ -1385,10 +1385,9 @@ dpkg-deb -x /tmp/libasound2-dev_1.0.25-4_armhf.deb .</code></pre></li>
 can specify it by <code>--with-alsa</code>.</p></li>
 </ul>
 <h4 id="x11-1">X11</h4>
-<p>You will need X11 libraries suitable for your <em>target</em> system.
-In most cases, using Debian's pre-built libraries work fine.</p>
-<p>Note that X11 is needed even if you only want to build a headless
-JDK.</p>
+<p>When not building a headless JDK, you will need X11 libraries
+suitable for your <em>target</em> system. In most cases, using Debian's
+pre-built libraries work fine.</p>
 <ul>
 <li><p>Go to <a href="https://www.debian.org/distrib/packages">Debian
 Package Search</a>, search for the following packages for your
diff --git a/doc/building.md b/doc/building.md
index b626027f101..d653d36eb55 100644
--- a/doc/building.md
+++ b/doc/building.md
@@ -1178,10 +1178,8 @@ Note that alsa is needed even if you only want to build a headless JDK.
 
 #### X11
 
-You will need X11 libraries suitable for your *target* system. In most cases,
-using Debian's pre-built libraries work fine.
-
-Note that X11 is needed even if you only want to build a headless JDK.
+When not building a headless JDK, you will need X11 libraries suitable for your
+*target* system. In most cases, using Debian's pre-built libraries work fine.
 
 * Go to [Debian Package Search](https://www.debian.org/distrib/packages),
   search for the following packages for your *target* system, and download them
diff --git a/make/autoconf/libraries.m4 b/make/autoconf/libraries.m4
index 8dc3d55ed0c..5daacdc1ced 100644
--- a/make/autoconf/libraries.m4
+++ b/make/autoconf/libraries.m4
@@ -42,12 +42,12 @@ m4_include([lib-tests.m4])
 AC_DEFUN_ONCE([LIB_DETERMINE_DEPENDENCIES],
 [
   # Check if X11 is needed
-  if test "x$OPENJDK_TARGET_OS" = xwindows || test "x$OPENJDK_TARGET_OS" = xmacosx; then
-    # No X11 support on windows or macosx
+  if test "x$OPENJDK_TARGET_OS" = xwindows ||
+     test "x$OPENJDK_TARGET_OS" = xmacosx ||
+     test "x$ENABLE_HEADLESS_ONLY" = xtrue; then
     NEEDS_LIB_X11=false
   else
-    # All other instances need X11, even if building headless only, libawt still
-    # needs X11 headers.
+    # All other instances need X11 for libawt.
     NEEDS_LIB_X11=true
   fi
 
diff --git a/make/modules/java.desktop/lib/AwtLibraries.gmk b/make/modules/java.desktop/lib/AwtLibraries.gmk
index 463e09e12dc..8b6b50b9e62 100644
--- a/make/modules/java.desktop/lib/AwtLibraries.gmk
+++ b/make/modules/java.desktop/lib/AwtLibraries.gmk
@@ -88,6 +88,10 @@ LIBAWT_EXTRA_HEADER_DIRS := \
 
 LIBAWT_CFLAGS := -D__MEDIALIB_OLD_NAMES -D__USE_J2D_NAMES -DMLIB_NO_LIBSUNMATH
 
+ifeq ($(ENABLE_HEADLESS_ONLY), true)
+  LIBAWT_CFLAGS += -DHEADLESS
+endif
+
 ifeq ($(call isTargetOs, windows), true)
   LIBAWT_CFLAGS += -EHsc -DUNICODE -D_UNICODE -DMLIB_OS64BIT
   LIBAWT_RCFLAGS ?= -I$(TOPDIR)/src/java.base/windows/native/launcher/icons
@@ -167,11 +171,18 @@ ifeq ($(call isTargetOs, windows macosx), false)
       $(TOPDIR)/src/$(MODULE)/$(OPENJDK_TARGET_OS_TYPE)/native/common/awt \
       #
 
+  LIBAWT_HEADLESS_EXCLUDE_FILES := \
+      GLXGraphicsConfig.c \
+      GLXSurfaceData.c \
+      X11PMBlitLoops.c \
+      X11Renderer.c \
+      X11SurfaceData.c \
+      #
+
   LIBAWT_HEADLESS_EXTRA_HEADER_DIRS := \
       $(LIBAWT_DEFAULT_HEADER_DIRS) \
       common/awt/debug \
       common/font \
-      common/java2d/opengl \
       java.base:libjvm \
       #
 
@@ -191,7 +202,8 @@ ifeq ($(call isTargetOs, windows macosx), false)
   $(eval $(call SetupJdkLibrary, BUILD_LIBAWT_HEADLESS, \
       NAME := awt_headless, \
       EXTRA_SRC := $(LIBAWT_HEADLESS_EXTRA_SRC), \
-      EXCLUDES := medialib, \
+      EXCLUDES := medialib opengl, \
+      EXCLUDE_FILES := $(LIBAWT_HEADLESS_EXCLUDE_FILES), \
       ONLY_EXPORTED := $(LIBAWT_HEADLESS_ONLY_EXPORTED), \
       OPTIMIZATION := LOW, \
       CFLAGS := -DHEADLESS=true $(CUPS_CFLAGS) $(FONTCONFIG_CFLAGS) \
diff --git a/src/java.desktop/unix/native/common/awt/utility/rect.h b/src/java.desktop/unix/native/common/awt/utility/rect.h
index ceea38f4349..91b5a17ec58 100644
--- a/src/java.desktop/unix/native/common/awt/utility/rect.h
+++ b/src/java.desktop/unix/native/common/awt/utility/rect.h
@@ -28,7 +28,7 @@
 #ifndef _AWT_RECT_H
 #define _AWT_RECT_H
 
-#ifndef MACOSX
+#if !defined(HEADLESS) && !defined(MACOSX)
 #include <X11/Xlib.h>
 typedef XRectangle RECT_T;
 #else
@@ -39,7 +39,7 @@ typedef struct {
     int width;
     int height;
 } RECT_T;
-#endif /* !MACOSX */
+#endif /* !HEADLESS && !MACOSX */
 
 #define RECT_EQ_X(r1,r2)        ((r1).x==(r2).x && (r1).width==(r2).width)