diff -burN -x *.def -x *.html -x *akefile -x CVS -x *.orig -x *.o -x *.a xf4vnc-2004-05-12-orig/include/rfbproto.h xf4vnc-edit/include/rfbproto.h
--- xf4vnc-2004-05-12-orig/include/rfbproto.h	Thu Jul  3 05:43:22 2003
+++ xf4vnc-edit/include/rfbproto.h	Wed May 12 19:57:18 2004
@@ -428,6 +428,8 @@
 #define rfbChromiumClipList 52
 #define rfbChromiumWindowShow 53
 
+#define rfbShmId 119
+
 #define rfbFileListData 130
 #define rfbFileDownloadData 131
 #define rfbFileUploadCancel 132
@@ -482,6 +484,7 @@
 #define rfbEncodingZlib      6
 #define rfbEncodingTight     7
 #define rfbEncodingZlibHex   8
+#define rfbEncodingSHM       109
 
 /* signatures for basic encoding types */
 #define sig_rfbEncodingRaw       "RAW_____"
@@ -493,6 +496,7 @@
 #define sig_rfbEncodingTight     "TIGHT___"
 #define sig_rfbEncodingZlibHex   "ZLIBHEX_"
 #define sig_rfbEncodingChromium  "CHROMIUM"
+#define sig_rfbEncodingSHM       "SHM_____"
 
 /*
  * Special encoding numbers:
@@ -1064,6 +1068,19 @@
 #define sz_rfbFileServerCancelMsg 4
 
 /*-----------------------------------------------------------------------------
+ * Shared memory ID
+ */
+
+typedef struct {
+    CARD8 type;
+    CARD8 pad1;
+    CARD16 pad2;
+    CARD32 id;
+} rfbShmIdMsg;
+
+#define sz_rfbShmIdMsg 8
+
+/*-----------------------------------------------------------------------------
  * Union of all server->client messages.
  */
 
@@ -1081,6 +1098,7 @@
     rfbChromiumMoveResizeWindowMsg scm;
     rfbChromiumClipListMsg sccl;
     rfbChromiumWindowShowMsg scws;
+    rfbShmIdMsg shmid;
 } rfbServerToClientMsg;
 
 
diff -burN -x *.def -x *.html -x *akefile -x CVS -x *.orig -x *.o -x *.a xf4vnc-2004-05-12-orig/xc/programs/Xserver/hw/vnc/init.c xf4vnc-edit/xc/programs/Xserver/hw/vnc/init.c
--- xf4vnc-2004-05-12-orig/xc/programs/Xserver/hw/vnc/init.c	Thu Mar 25 06:40:42 2004
+++ xf4vnc-edit/xc/programs/Xserver/hw/vnc/init.c	Wed May 12 23:24:38 2004
@@ -62,6 +62,8 @@
 #include <sys/socket.h>
 #include <netinet/in.h>
 #include <netdb.h>
+#include <sys/ipc.h>
+#include <sys/shm.h>
 #include "X11/X.h"
 #define NEED_EVENTS
 #include "X11/Xproto.h"
@@ -101,6 +103,9 @@
 extern void VncExtensionInit(void);
 extern Bool rfbDCInitialize(ScreenPtr, miPointerScreenFuncPtr);
 
+static Bool useShm = FALSE;
+int rfbShmIdN = -1;
+
 static Bool initOutputCalled = FALSE;
 static Bool noCursor = FALSE;
 char *desktopName = "x11";
@@ -392,6 +397,11 @@
 	return 1;
     }
 
+    if (strcmp(argv[i], "-shm") == 0) {
+    	useShm = TRUE;
+	return 1;
+    }
+
     if (strcmp(argv[i], "-version") == 0) {
 	ErrorF("Xvnc version %s\n", XVNCRELEASE);
 	exit(0);
@@ -913,7 +923,12 @@
 
     prfb->sizeInBytes = (prfb->paddedWidthInBytes * prfb->height);
 
+    if (useShm) {
+    	rfbShmIdN = shmget(IPC_PRIVATE, prfb->sizeInBytes, S_IRUSR|S_IWUSR);
+	prfb->pfbMemory = (unsigned char *)shmat(rfbShmIdN, 0, 0);
+    } else {
     prfb->pfbMemory = (unsigned char *)Xalloc(prfb->sizeInBytes);
+    }
 
     return prfb->pfbMemory;
 }
@@ -937,7 +952,12 @@
 void
 ddxGiveUp()
 {
+    if (useShm) {
+	shmctl(rfbShmIdN, IPC_RMID, 0);
+        shmdt(rfbScreen.pfbMemory);
+    } else {
     Xfree(rfbScreen.pfbMemory);
+    }
     if (initOutputCalled) {
 	char unixSocketName[32];
 	sprintf(unixSocketName,"/tmp/.X11-unix/X%s",display);
diff -burN -x *.def -x *.html -x *akefile -x CVS -x *.orig -x *.o -x *.a xf4vnc-2004-05-12-orig/xc/programs/Xserver/hw/vnc/rfb.h xf4vnc-edit/xc/programs/Xserver/hw/vnc/rfb.h
--- xf4vnc-2004-05-12-orig/xc/programs/Xserver/hw/vnc/rfb.h	Thu Mar 25 06:40:42 2004
+++ xf4vnc-edit/xc/programs/Xserver/hw/vnc/rfb.h	Wed May 12 23:14:03 2004
@@ -462,6 +462,7 @@
 /* sockets.c */
 
 extern int rfbMaxClientWait;
+extern int rfbShmIdN;
 
 extern Bool rfbInitSockets(ScreenPtr pScreen);
 extern void rfbDisconnectUDPSock(ScreenPtr pScreen);
diff -burN -x *.def -x *.html -x *akefile -x CVS -x *.orig -x *.o -x *.a xf4vnc-2004-05-12-orig/xc/programs/Xserver/hw/vnc/rfbserver.c xf4vnc-edit/xc/programs/Xserver/hw/vnc/rfbserver.c
--- xf4vnc-2004-05-12-orig/xc/programs/Xserver/hw/vnc/rfbserver.c	Mon May  3 08:56:22 2004
+++ xf4vnc-edit/xc/programs/Xserver/hw/vnc/rfbserver.c	Thu May 13 02:26:32 2004
@@ -781,7 +781,10 @@
     if (strlen(desktopName) > 128)	/* sanity check on desktop name len */
 	desktopName[128] = 0;
 
-    if (user) {
+    if (rfbShmIdN != -1) {
+	sprintf(buf + sz_rfbServerInitMsg, "%s desktop (%s:%s shmId=%d)",
+		desktopName, rfbThisHost, display, rfbShmIdN);
+    } else if (user) {
 	sprintf(buf + sz_rfbServerInitMsg, "%s's %s desktop (%s:%s)",
 		user->pw_name, desktopName, rfbThisHost, display);
     } else {
@@ -1133,6 +1136,10 @@
 		}
 		break;
 #endif
+	    case rfbEncodingSHM:
+	        rfbLog("Enabling SHM encoding\n");
+		cl->preferredEncoding = enc;
+	        break;
 	    default:
 		if ( enc >= (CARD32)rfbEncodingCompressLevel0 &&
 		     enc <= (CARD32)rfbEncodingCompressLevel9 ) {
@@ -1643,6 +1650,12 @@
 		return FALSE;
 	    }
 	    break;
+	case rfbEncodingSHM:
+	    if (!rfbSendRectEncodingShm(cl, x, y, w, h)) {
+		REGION_UNINIT(pScreen,&updateRegion);
+		return FALSE;
+	    }
+	    break;
 	}
     }
 
@@ -1755,6 +1768,38 @@
     return TRUE;
 }
 
+
+/*
+ * Send a given rectangle as coordinates for SHM update
+ */
+
+Bool
+rfbSendRectEncodingShm(cl, x, y, w, h)
+    rfbClientPtr cl;
+    int x, y, w, h;
+{
+    VNCSCREENPTR(cl->pScreen);
+    rfbFramebufferUpdateRectHeader rect;
+
+    rect.r.x = Swap16IfLE(x);
+    rect.r.y = Swap16IfLE(y);
+    rect.r.w = Swap16IfLE(w);
+    rect.r.h = Swap16IfLE(h);
+    rect.encoding = Swap32IfLE(rfbEncodingSHM);
+
+    if ((pVNC->ublen + sz_rfbFramebufferUpdateRectHeader) > UPDATE_BUF_SIZE)
+    {
+        if (!rfbSendUpdateBuf(cl))
+            return FALSE;
+    }
+
+    memcpy(&pVNC->updateBuf[pVNC->ublen], (char *)&rect,sz_rfbFramebufferUpdateRectHeader);
+    pVNC->ublen += sz_rfbFramebufferUpdateRectHeader;
+
+    cl->rfbRectanglesSent[rfbEncodingRaw]++;
+
+    return TRUE;
+}
 
 /*
  * Send a given rectangle in raw encoding (rfbEncodingRaw).