Add gbm (generic/graphics buffer manager)
diff --git a/configure.ac b/configure.ac
index c9dd8a7..b5dee9d 100644
--- a/configure.ac
+++ b/configure.ac
@@ -352,6 +352,7 @@
 VG_LIB_NAME='lib$(VG_LIB).'${LIB_EXTENSION}
 GLAPI_LIB_NAME='lib$(GLAPI_LIB).'${LIB_EXTENSION}
 WAYLAND_EGL_LIB_NAME='lib$(WAYLAND_EGL_LIB).'${LIB_EXTENSION}
+GBM_LIB_NAME='lib$(GBM_LIB).'${LIB_EXTENSION}
 
 GL_LIB_GLOB=${LIB_PREFIX_GLOB}'$(GL_LIB)'${LIB_VERSION_SEPARATOR}'*'${LIB_EXTENSION}'*'
 GLU_LIB_GLOB=${LIB_PREFIX_GLOB}'$(GLU_LIB)'${LIB_VERSION_SEPARATOR}'*'${LIB_EXTENSION}'*'
@@ -365,6 +366,7 @@
 VG_LIB_GLOB=${LIB_PREFIX_GLOB}'$(VG_LIB)'${LIB_VERSION_SEPARATOR}'*'${LIB_EXTENSION}'*'
 GLAPI_LIB_GLOB=${LIB_PREFIX_GLOB}'$(GLAPI_LIB)'${LIB_VERSION_SEPARATOR}'*'${LIB_EXTENSION}'*'
 WAYLAND_EGL_LIB_GLOB=${LIB_PREFIX_GLOB}'$(WAYLAND_EGL_LIB)'${LIB_VERSION_SEPARATOR}'*'${LIB_EXTENSION}'*'
+GBM_LIB_GLOB=${LIB_PREFIX_GLOB}'$(GBM_LIB)'${LIB_VERSION_SEPARATOR}'*'${LIB_EXTENSION}'*'
 
 AC_SUBST([GL_LIB_NAME])
 AC_SUBST([GLU_LIB_NAME])
@@ -377,6 +379,7 @@
 AC_SUBST([VG_LIB_NAME])
 AC_SUBST([GLAPI_LIB_NAME])
 AC_SUBST([WAYLAND_EGL_LIB_NAME])
+AC_SUBST([GBM_LIB_NAME])
 
 AC_SUBST([GL_LIB_GLOB])
 AC_SUBST([GLU_LIB_GLOB])
@@ -389,6 +392,7 @@
 AC_SUBST([VG_LIB_GLOB])
 AC_SUBST([GLAPI_LIB_GLOB])
 AC_SUBST([WAYLAND_EGL_LIB_GLOB])
+AC_SUBST([GBM_LIB_GLOB])
 
 dnl
 dnl Arch/platform-specific settings
@@ -543,6 +547,11 @@
         [disable EGL library @<:@default=enabled@:>@])],
     [enable_egl="$enableval"],
     [enable_egl=yes])
+AC_ARG_ENABLE([gbm],
+   [AS_HELP_STRING([--enable-gbm],
+         [enable gbm library @<:@default=auto@:>@])],
+   [enable_gbm="$enableval"],
+   [enable_gbm=auto])
 AC_ARG_ENABLE([gallium_egl],
     [AS_HELP_STRING([--enable-gallium-egl],
         [enable optional EGL state tracker (not required
@@ -1245,6 +1254,34 @@
 AC_SUBST([EGL_DRIVERS_DIRS])
 
 dnl
+dnl gbm configuration
+dnl
+if test "x$enable_gbm" = xauto; then
+    case "$with_egl_platforms" in
+        *drm*)
+            enable_gbm=yes ;;
+         *)
+            enable_gbm=no ;;
+    esac
+fi
+if test "x$enable_gbm" = xyes; then
+    SRC_DIRS="$SRC_DIRS gbm"
+    GBM_BACKEND_DIRS=""
+
+    PKG_CHECK_MODULES([LIBUDEV], [libudev], [],
+                      AC_MSG_ERROR([gbm needs udev]))
+    GBM_LIB_DEPS="$DLOPEN_LIBS $LIBUDEV_LIBS"
+fi
+AC_SUBST([GBM_LIB_DEPS])
+AC_SUBST([GBM_BACKEND_DIRS])
+GBM_PC_REQ_PRIV="libudev"
+GBM_PC_LIB_PRIV="$DLOPEN_LIBS"
+GBM_PC_CFLAGS=
+AC_SUBST([GBM_PC_REQ_PRIV])
+AC_SUBST([GBM_PC_LIB_PRIV])
+AC_SUBST([GBM_PC_CFLAGS])
+
+dnl
 dnl EGL Gallium configuration
 dnl
 if test "x$enable_gallium_egl" = xyes; then