8376684: Compile OpenJDK in headless mode without required X11 libraries

doc/building.html

@@ -603,8 +603,9 @@ <h4 id="alsa-1">ALSA</h4>
 <li>If alsa is not properly detected by <code>configure</code>, you can point it out by <code>--with-alsa</code>.</li>
 </ul>
 <h4 id="x11-1">X11</h4>
-<p>You will need X11 libraries suitable for your <em>target</em> system. For 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>Go to <a href="https://www.debian.org/distrib/packages">Debian Package Search</a>, search for the following packages for your <em>target</em> system, and download them to /tmp/target-x11:
 <ul>

doc/building.md

@@ -1077,10 +1077,8 @@ dpkg-deb -x /tmp/libasound2-dev_1.0.25-4_armhf.deb .
 
 #### X11
 
-You will need X11 libraries suitable for your *target* system. For 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

make/modules/java.desktop/lib/Awt2dLibraries.gmk

@@ -77,6 +77,10 @@ ifeq ($(call isTargetOs, windows), true)
       #
 endif
 
+ifeq ($(ENABLE_HEADLESS_ONLY), true)
+  LIBAWT_CFLAGS += -DHEADLESS
+endif
+
 ifeq ($(call isTargetOs, linux macosx aix), true)
   LIBAWT_EXFILES += awt_Font.c CUPSfuncs.c fontpath.c X11Color.c
 endif
@@ -369,13 +373,20 @@ ifeq ($(call isTargetOs, windows macosx), false)
       $(TOPDIR)/src/$(MODULE)/$(OPENJDK_TARGET_OS_TYPE)/native/common/awt \
       #
 
-  LIBAWT_HEADLESS_EXCLUDES := medialib
+  LIBAWT_HEADLESS_EXCLUDES := medialib opengl
+
+  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 \
       #
 
   LIBAWT_HEADLESS_CFLAGS := $(CUPS_CFLAGS) $(FONTCONFIG_CFLAGS) $(X_CFLAGS) \
@@ -385,6 +396,7 @@ ifeq ($(call isTargetOs, windows macosx), false)
       NAME := awt_headless, \
       EXTRA_SRC := $(LIBAWT_HEADLESS_EXTRA_SRC), \
       EXCLUDES := $(LIBAWT_HEADLESS_EXCLUDES), \
+      EXCLUDE_FILES := $(LIBAWT_HEADLESS_EXCLUDE_FILES), \
       OPTIMIZATION := LOW, \
       CFLAGS := $(CFLAGS_JDKLIB) \
           $(LIBAWT_HEADLESS_CFLAGS), \

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)