diff --git a/dix/dispatch.c b/dix/dispatch.c
index d09ec2697..d9d86374d 100644
--- a/dix/dispatch.c
+++ b/dix/dispatch.c
@@ -122,6 +122,7 @@ Equipment Corporation.
 #include "os/screensaver.h"
 
 #include "windowstr.h"
+#include "ddx.h"
 #include "dixfontstr.h"
 #include "gcstruct.h"
 #include "cursorstr.h"
diff --git a/dix/main.c b/dix/main.c
index cf83a6346..8423a15f3 100644
--- a/dix/main.c
+++ b/dix/main.c
@@ -111,6 +111,7 @@ Equipment Corporation.
 #include "extension.h"
 #include "cursorstr.h"
 #include "servermd.h"
+#include "ddx.h"
 #include "dixfont.h"
 #include "extnsionst.h"
 #include "privates.h"
diff --git a/hw/kdrive/ephyr/ephyrinit.c b/hw/kdrive/ephyr/ephyrinit.c
index 9306f3367..742f98ac1 100644
--- a/hw/kdrive/ephyr/ephyrinit.c
+++ b/hw/kdrive/ephyr/ephyrinit.c
@@ -30,6 +30,7 @@
 #include "os/ddx_priv.h"
 #include "os/osdep.h"
 
+#include "ddx.h"
 #include "ephyr.h"
 #include "ephyrlog.h"
 #include "glx_extinit.h"
diff --git a/hw/vfb/InitOutput.c b/hw/vfb/InitOutput.c
index cd3b2e0a8..daf02ccf9 100644
--- a/hw/vfb/InitOutput.c
+++ b/hw/vfb/InitOutput.c
@@ -70,6 +70,7 @@ from The Open Group.
 #include <sys/ipc.h>
 #include <sys/shm.h>
 #endif                          /* MITSHM */
+#include "ddx.h"
 #include "dix.h"
 #include "miline.h"
 #include "glx_extinit.h"
diff --git a/hw/xfree86/common/xf86Configure.c b/hw/xfree86/common/xf86Configure.c
index 6242cad50..1158bc409 100644
--- a/hw/xfree86/common/xf86Configure.c
+++ b/hw/xfree86/common/xf86Configure.c
@@ -32,6 +32,7 @@
 #include "os/ddx_priv.h"
 #include "os/osdep.h"
 
+#include "ddx.h"
 #include "xf86.h"
 #include "xf86Config.h"
 #include "xf86_OSlib.h"
diff --git a/hw/xnest/Args.c b/hw/xnest/Args.c
index 32add64ed..0fe74d83c 100644
--- a/hw/xnest/Args.c
+++ b/hw/xnest/Args.c
@@ -25,7 +25,7 @@ is" without express or implied warranty.
 #include "misc.h"
 #include "scrnintstr.h"
 #include "servermd.h"
-#include "extinit.h"
+#include "os/ddx.h"
 
 #include "xnest-xcb.h"
 
diff --git a/hw/xnest/Init.c b/hw/xnest/Init.c
index ffa94b075..c4f5b9e4a 100644
--- a/hw/xnest/Init.c
+++ b/hw/xnest/Init.c
@@ -26,6 +26,7 @@ is" without express or implied warranty.
 #include "os/ddx_priv.h"
 #include "os/osdep.h"
 
+#include "ddx.h"
 #include "screenint.h"
 #include "input.h"
 #include "misc.h"
diff --git a/hw/xquartz/darwin.c b/hw/xquartz/darwin.c
index 8b6c3c2ee..45e279444 100644
--- a/hw/xquartz/darwin.c
+++ b/hw/xquartz/darwin.c
@@ -46,6 +46,7 @@
 #include "micmap.h"             // mi colormap code
 #include "fb.h"                 // fb framebuffer code
 #include "globals.h"
+#include "ddx.h"
 #include "dix.h"
 #include "xkbsrv.h"
 
diff --git a/hw/xwayland/xwayland.c b/hw/xwayland/xwayland.c
index 99cc68010..cb540b89f 100644
--- a/hw/xwayland/xwayland.c
+++ b/hw/xwayland/xwayland.c
@@ -53,6 +53,7 @@
 #include <glx_extinit.h>
 #include <opaque.h>
 #include <os.h>
+#include "ddx.h"
 #include <propertyst.h>
 #include <version-config.h>
 #include "extinit.h"
diff --git a/hw/xwin/winprocarg.c b/hw/xwin/winprocarg.c
index 56280c232..ed6a91328 100644
--- a/hw/xwin/winprocarg.c
+++ b/hw/xwin/winprocarg.c
@@ -47,6 +47,7 @@ from The Open Group.
 #include "winprefs.h"
 
 #include "winclipboard/winclipboard.h"
+#include "ddx.h"
 
 /*
  * Function prototypes
diff --git a/meson.build b/meson.build
index 93f20c97a..b66b6b0fa 100644
--- a/meson.build
+++ b/meson.build
@@ -671,6 +671,7 @@ inc = include_directories(
     'dix',
     'dri3',
     'include',
+    'os',
     'present',
     'randr',
     'render',
diff --git a/os/ddx.h b/os/ddx.h
new file mode 100644
index 000000000..1f90e099d
--- /dev/null
+++ b/os/ddx.h
@@ -0,0 +1,27 @@
+/* SPDX-License-Identifier: MIT OR X11
+ *
+ * Copyright © 2024 Enrico Weigelt, metux IT consult <info@metux.net>
+ */
+#ifndef _XSERVER_OS_DDX_H
+#define _XSERVER_OS_DDX_H
+
+#include "os.h"
+
+/* callbacks of the DDX, which are called by DIX or OS layer.
+   DDX's need to implement these in order to handle DDX specific things.
+*/
+
+/* called before server reset */
+void ddxBeforeReset(void);
+
+/* called by ProcessCommandLine, so DDX can catch cmdline args */
+int ddxProcessArgument(int argc, char *argv[], int i);
+
+/* print DDX specific usage message */
+void ddxUseMsg(void);
+
+void ddxGiveUp(enum ExitCode error);
+
+void ddxInputThreadInit(void);
+
+#endif /* _XSERVER_OS_DDX_H */
diff --git a/os/log.c b/os/log.c
index 69b0bb6ca..8f74a5eb9 100644
--- a/os/log.c
+++ b/os/log.c
@@ -97,6 +97,7 @@ OR PERFORMANCE OF THIS SOFTWARE.
 #include "os/osdep.h"
 
 #include "opaque.h"
+#include "ddx.h"
 
 #ifdef XF86BIGFONT
 #include "xf86bigfontsrv.h"
diff --git a/os/utils.c b/os/utils.c
index 528ea90ab..4b97fe6eb 100644
--- a/os/utils.c
+++ b/os/utils.c
@@ -118,6 +118,7 @@ __stdcall unsigned long GetTickCount(void);
 #include "dixstruct.h"
 #include "picture.h"
 #include "miinitext.h"
+#include "ddx.h"
 #include "present.h"
 #include "dixstruct_priv.h"
 #include "dpmsproc.h"