Index: sys/dev/atkbdc/psm.c
===================================================================
--- sys/dev/atkbdc/psm.c	(revision 200181)
+++ sys/dev/atkbdc/psm.c	(working copy)
@@ -343,6 +343,9 @@
 #define	PSM_FLAGS_FINGERDOWN	0x0001	/* VersaPad finger down */
 
 /* Tunables */
+static int tap_enabled = 1;
+TUNABLE_INT("hw.psm.tap_enabled", &tap_enabled);
+
 static int synaptics_support = 0;
 TUNABLE_INT("hw.psm.synaptics_support", &synaptics_support);
 
@@ -901,6 +904,36 @@
 		}
 	}
 
+	/*
+	 * A user may want to disable tap and drag gestures on a Synaptics
+	 * TouchPad when it operates in Relative Mode.
+	 */
+	if (sc->hw.model == MOUSE_MODEL_GENERIC) {
+		if (tap_enabled) {
+			/*
+			 * Enable tap & drag gestures. We use a Mode Byte
+			 * and clear the DisGest bit (see §2.5 of Synaptics
+			 * TouchPad Interfacing Guide).
+			 */
+			VLOG(2, (LOG_DEBUG,
+			    "psm%d: enable tap and drag gestures\n",
+			    sc->unit));
+			mouse_ext_command(sc->kbdc, 0x00);
+			set_mouse_sampling_rate(sc->kbdc, 20);
+		} else {
+			/*
+			 * Disable tap & drag gestures. We use a Mode Byte
+			 * and set the DisGest bit (see §2.5 of Synaptics
+			 * TouchPad Interfacing Guide).
+			 */
+			VLOG(2, (LOG_DEBUG,
+			    "psm%d: disable tap and drag gestures\n",
+			    sc->unit));
+			mouse_ext_command(sc->kbdc, 0x04);
+			set_mouse_sampling_rate(sc->kbdc, 20);
+		}
+	}
+
 	/* enable the mouse device */
 	if (!enable_aux_dev(sc->kbdc)) {
 		/* MOUSE ERROR: failed to enable the mouse because:
@@ -2261,6 +2294,8 @@
 SYSCTL_INT(_debug_psm, OID_AUTO, pkterrthresh, CTLFLAG_RW, &pkterrthresh, 0,
     "Number of error packets allowed before reinitializing the mouse");
 
+SYSCTL_INT(_hw_psm, OID_AUTO, tap_enabled, CTLFLAG_RW, &tap_enabled, 0,
+    "Enable tap and drag gestures");
 static int tap_threshold = PSM_TAP_THRESHOLD;
 SYSCTL_INT(_hw_psm, OID_AUTO, tap_threshold, CTLFLAG_RW, &tap_threshold, 0,
     "Button tap threshold");
Index: share/man/man4/psm.4
===================================================================
--- share/man/man4/psm.4	(revision 200181)
+++ share/man/man4/psm.4	(working copy)
@@ -359,6 +359,18 @@
 This will enable
 .Nm
 to handle packets from guest devices (sticks) and extra buttons.
+.Pp
+Tap and drag gestures can be disabled by setting
+.Va hw.psm.tap_enabled
+to
+.Em 0
+at boot-time.
+Currently, this is only supported on Synaptics touchpads with Extended
+support disabled. The behaviour may be changed after boot by setting
+the sysctl with the same name and by restarting
+.Xr moused 8
+using
+.Pa /etc/rc.d/moused .
 .Sh IOCTLS
 There are a few
 .Xr ioctl 2