diff --git a/drivers/dahdi/xpp/card_bri.c b/drivers/dahdi/xpp/card_bri.c
index 5476281..9f41294 100644
--- a/drivers/dahdi/xpp/card_bri.c
+++ b/drivers/dahdi/xpp/card_bri.c
@@ -467,8 +467,8 @@ static int rx_dchan(xpd_t *xpd, reg_cmd_t *regcmd)
 	int ret = 0;
 
 	src = REG_XDATA(regcmd);
-	len = regcmd->bytes;
-	eoframe = regcmd->eoframe;
+	len = regcmd->h.bytes;
+	eoframe = regcmd->h.eoframe;
 	if (len <= 0)
 		return 0;
 	if (!SPAN_REGISTERED(xpd))	/* Nowhere to copy data */
@@ -566,10 +566,10 @@ static void fill_multibyte(xpd_t *xpd, xpacket_t *pack,
 	XPACKET_INIT(pack, GLOBAL, REGISTER_REQUEST, xpd->xbus_idx, 0, 0);
 	XPACKET_LEN(pack) = RPACKET_SIZE(GLOBAL, REGISTER_REQUEST);
 	reg_cmd = &RPACKET_FIELD(pack, GLOBAL, REGISTER_REQUEST, reg_cmd);
-	reg_cmd->bytes = len;
-	reg_cmd->is_multibyte = 1;
-	reg_cmd->portnum = xpd->addr.subunit;
-	reg_cmd->eoframe = eoframe;
+	reg_cmd->h.bytes = len;
+	reg_cmd->h.is_multibyte = 1;
+	reg_cmd->h.portnum = xpd->addr.subunit;
+	reg_cmd->h.eoframe = eoframe;
 	p = REG_XDATA(reg_cmd);
 	memcpy(p, buf, len);
 	if (debug)
@@ -1537,7 +1537,7 @@ static int BRI_card_register_reply(xbus_t *xbus, xpd_t *xpd, reg_cmd_t *info)
 	/* Map UNIT + PORTNUM to XPD */
 	orig_xpd = xpd;
 	addr.unit = orig_xpd->addr.unit;
-	addr.subunit = info->portnum;
+	addr.subunit = info->h.portnum;
 	xpd = xpd_byaddr(xbus, addr.unit, addr.subunit);
 	if (!xpd) {
 		static int rate_limit;
@@ -1562,9 +1562,9 @@ static int BRI_card_register_reply(xbus_t *xbus, xpd_t *xpd, reg_cmd_t *info)
 			XPD_DBG(REGS, xpd, "Got SU_RD_STA=%02X\n",
 				REG_FIELD(info, data_low));
 	}
-	if (info->is_multibyte) {
+	if (info->h.is_multibyte) {
 		XPD_DBG(REGS, xpd, "Got Multibyte: %d bytes, eoframe: %d\n",
-			info->bytes, info->eoframe);
+			info->h.bytes, info->h.eoframe);
 		ret = rx_dchan(xpd, info);
 		if (ret < 0) {
 			priv->dchan_rx_drops++;
diff --git a/drivers/dahdi/xpp/card_echo.c b/drivers/dahdi/xpp/card_echo.c
index c6e6046..e7b16a8 100644
--- a/drivers/dahdi/xpp/card_echo.c
+++ b/drivers/dahdi/xpp/card_echo.c
@@ -112,7 +112,7 @@ static int ECHO_card_register_reply(xbus_t *xbus, xpd_t *xpd, reg_cmd_t *info)
 	/* Map UNIT + PORTNUM to XPD */
 	orig_xpd = xpd;
 	addr.unit = orig_xpd->addr.unit;
-	addr.subunit = info->portnum;
+	addr.subunit = info->h.portnum;
 	xpd = xpd_byaddr(xbus, addr.unit, addr.subunit);
 	if (!xpd) {
 		static int rate_limit;
diff --git a/drivers/dahdi/xpp/card_fxo.c b/drivers/dahdi/xpp/card_fxo.c
index 4b8697f..3a70c4e 100644
--- a/drivers/dahdi/xpp/card_fxo.c
+++ b/drivers/dahdi/xpp/card_fxo.c
@@ -1246,7 +1246,7 @@ static int FXO_card_register_reply(xbus_t *xbus, xpd_t *xpd, reg_cmd_t *info)
 
 	priv = xpd->priv;
 	BUG_ON(!priv);
-	portno = info->portnum;
+	portno = info->h.portnum;
 	switch (REG_FIELD(info, regnum)) {
 	case REG_INTERRUPT_SRC:
 		got_chip_interrupt(xpd, REG_FIELD(info, data_low), portno);
@@ -1264,7 +1264,7 @@ static int FXO_card_register_reply(xbus_t *xbus, xpd_t *xpd, reg_cmd_t *info)
 #endif
 	}
 	LINE_DBG(REGS, xpd, portno, "%c reg_num=0x%X, dataL=0x%X dataH=0x%X\n",
-		 ((info->bytes == 3) ? 'I' : 'D'), REG_FIELD(info, regnum),
+		 ((info->h.bytes == 3) ? 'I' : 'D'), REG_FIELD(info, regnum),
 		 REG_FIELD(info, data_low), REG_FIELD(info, data_high));
 	/* Update /proc info only if reply relate to the last slic read request */
 	if (REG_FIELD(&xpd->requested_reply, regnum) ==
diff --git a/drivers/dahdi/xpp/card_fxs.c b/drivers/dahdi/xpp/card_fxs.c
index b403b2a..9fd7ef6 100644
--- a/drivers/dahdi/xpp/card_fxs.c
+++ b/drivers/dahdi/xpp/card_fxs.c
@@ -1484,7 +1484,7 @@ static void process_digital_inputs(xpd_t *xpd, const reg_cmd_t *info)
 {
 	int i;
 	bool offhook = (REG_FIELD(info, data_low) & 0x1) == 0;
-	xpp_line_t lines = BIT(info->portnum);
+	xpp_line_t lines = BIT(info->h.portnum);
 
 	/* Sanity check */
 	if (!PHONEDEV(xpd).digital_inputs) {
@@ -1593,7 +1593,7 @@ static int FXS_card_register_reply(xbus_t *xbus, xpd_t *xpd, reg_cmd_t *info)
 	if (!indirect && regnum == REG_DTMF_DECODE) {
 		__u8 val = REG_FIELD(info, data_low);
 
-		process_dtmf(xpd, info->portnum, val);
+		process_dtmf(xpd, info->h.portnum, val);
 	}
 #ifdef	POLL_DIGITAL_INPUTS
 	/*
@@ -1604,7 +1604,7 @@ static int FXS_card_register_reply(xbus_t *xbus, xpd_t *xpd, reg_cmd_t *info)
 #endif
 	else if (!indirect && regnum == REG_LOOPCLOSURE) {	/* OFFHOOK ? */
 		__u8 val = REG_FIELD(info, data_low);
-		xpp_line_t mask = BIT(info->portnum);
+		xpp_line_t mask = BIT(info->h.portnum);
 		xpp_line_t offhook;
 
 		/*
@@ -1613,7 +1613,7 @@ static int FXS_card_register_reply(xbus_t *xbus, xpd_t *xpd, reg_cmd_t *info)
 		 */
 		if ((val & REG_LOOPCLOSURE_ZERO) == 0) {
 			offhook = (val & REG_LOOPCLOSURE_LCR) ? mask : 0;
-			LINE_DBG(SIGNAL, xpd, info->portnum,
+			LINE_DBG(SIGNAL, xpd, info->h.portnum,
 				"REG_LOOPCLOSURE: dataL=0x%X "
 				"(offhook=0x%X mask=0x%X)\n",
 				val, offhook, mask);
diff --git a/drivers/dahdi/xpp/card_global.c b/drivers/dahdi/xpp/card_global.c
index b4c44af..ac7167e 100644
--- a/drivers/dahdi/xpp/card_global.c
+++ b/drivers/dahdi/xpp/card_global.c
@@ -58,10 +58,10 @@ static int send_magic_request(xbus_t *xbus, unsigned unit, xportno_t portno,
 	 */
 	XFRAME_NEW_CMD(xframe, pack, xbus, GLOBAL, REGISTER_REQUEST, unit);
 	reg_cmd = &RPACKET_FIELD(pack, GLOBAL, REGISTER_REQUEST, reg_cmd);
-	reg_cmd->bytes = 0;
-	reg_cmd->is_multibyte = 1;
-	reg_cmd->portnum = portno;
-	reg_cmd->eoframe = eoftx;
+	reg_cmd->h.bytes = 0;
+	reg_cmd->h.is_multibyte = 1;
+	reg_cmd->h.portnum = portno;
+	reg_cmd->h.eoframe = eoftx;
 	PORT_DBG(REGS, xbus, unit, portno, "Magic Packet (eoftx=%d)\n", eoftx);
 	if (debug & DBG_REGS)
 		dump_xframe(__func__, xbus, xframe, debug);
@@ -380,16 +380,16 @@ int xpp_register_request(xbus_t *xbus, xpd_t *xpd, xportno_t portno,
 		 data_low, data_high);
 	reg_cmd = &RPACKET_FIELD(pack, GLOBAL, REGISTER_REQUEST, reg_cmd);
 	/* do not count the 'bytes' field */
-	reg_cmd->bytes = sizeof(*reg_cmd) - 1;
-	reg_cmd->is_multibyte = 0;
+	reg_cmd->h.bytes = REG_CMD_SIZE(REG);
+	reg_cmd->h.is_multibyte = 0;
 	if (portno == PORT_BROADCAST) {
-		reg_cmd->portnum = 0;
+		reg_cmd->h.portnum = 0;
 		REG_FIELD(reg_cmd, all_ports_broadcast) = 1;
 	} else {
-		reg_cmd->portnum = portno;
+		reg_cmd->h.portnum = portno;
 		REG_FIELD(reg_cmd, all_ports_broadcast) = 0;
 	}
-	reg_cmd->eoframe = 0;
+	reg_cmd->h.eoframe = 0;
 	REG_FIELD(reg_cmd, reserved) = 0;	/* force reserved bits to 0 */
 	REG_FIELD(reg_cmd, read_request) = (writing) ? 0 : 1;
 	REG_FIELD(reg_cmd, do_subreg) = do_subreg;
@@ -402,7 +402,7 @@ int xpp_register_request(xbus_t *xbus, xpd_t *xpd, xportno_t portno,
 		xpd->requested_reply = *reg_cmd;
 	if (debug & DBG_REGS) {
 		dump_reg_cmd("REG_REQ", 1, xbus, xpd->addr.unit,
-			     reg_cmd->portnum, reg_cmd);
+			     reg_cmd->h.portnum, reg_cmd);
 		dump_packet("REG_REQ", pack, 1);
 	}
 	if (!xframe->usec_towait) {	/* default processing time of SPI */
@@ -591,7 +591,7 @@ HANDLER_DEF(GLOBAL, REGISTER_REPLY)
 		return -EPROTO;
 	}
 	if (debug & DBG_REGS) {
-		dump_reg_cmd("REG_REPLY", 0, xbus, xpd->addr.unit, reg->portnum,
+		dump_reg_cmd("REG_REPLY", 0, xbus, xpd->addr.unit, reg->h.portnum,
 			     reg);
 		dump_packet("REG_REPLY", pack, 1);
 	}
diff --git a/drivers/dahdi/xpp/card_pri.c b/drivers/dahdi/xpp/card_pri.c
index 96f1989..f8346a4 100644
--- a/drivers/dahdi/xpp/card_pri.c
+++ b/drivers/dahdi/xpp/card_pri.c
@@ -2253,7 +2253,7 @@ static int PRI_card_register_reply(xbus_t *xbus, xpd_t *xpd, reg_cmd_t *info)
 	/* Map UNIT + PORTNUM to XPD */
 	orig_xpd = xpd;
 	addr.unit = orig_xpd->addr.unit;
-	addr.subunit = info->portnum;
+	addr.subunit = info->h.portnum;
 	regnum = REG_FIELD(info, regnum);
 	data_low = REG_FIELD(info, data_low);
 	xpd = xpd_byaddr(xbus, addr.unit, addr.subunit);
@@ -2267,9 +2267,9 @@ static int PRI_card_register_reply(xbus_t *xbus, xpd_t *xpd, reg_cmd_t *info)
 	spin_lock_irqsave(&xpd->lock, flags);
 	priv = xpd->priv;
 	BUG_ON(!priv);
-	if (info->is_multibyte) {
+	if (info->h.is_multibyte) {
 		XPD_NOTICE(xpd, "Got Multibyte: %d bytes, eoframe: %d\n",
-			   info->bytes, info->eoframe);
+			   info->h.bytes, info->h.eoframe);
 		goto end;
 	}
 	if (regnum == REG_FRS0 && !REG_FIELD(info, do_subreg))
diff --git a/drivers/dahdi/xpp/xbus-sysfs.c b/drivers/dahdi/xpp/xbus-sysfs.c
index 74d1dcc..376215a 100644
--- a/drivers/dahdi/xpp/xbus-sysfs.c
+++ b/drivers/dahdi/xpp/xbus-sysfs.c
@@ -524,7 +524,7 @@ static DEVICE_ATTR_READER(chipregs_show, dev, buf)
 			    (do_datah) ? "\tDH" : "");
 		len +=
 		    sprintf(buf + len, "%2d\tRS\t%02X\t%02X\t%02X%s\n",
-			    regs->portnum, REG_FIELD(regs, regnum),
+			    regs->h.portnum, REG_FIELD(regs, regnum),
 			    REG_FIELD(regs, subreg), REG_FIELD(regs, data_low),
 			    datah_str);
 	} else {
@@ -532,7 +532,7 @@ static DEVICE_ATTR_READER(chipregs_show, dev, buf)
 		    sprintf(buf + len, "#CH\tOP\tReg.\tDL%s\n",
 			    (do_datah) ? "\tDH" : "");
 		len +=
-		    sprintf(buf + len, "%2d\tRD\t%02X\t%02X%s\n", regs->portnum,
+		    sprintf(buf + len, "%2d\tRD\t%02X\t%02X%s\n", regs->h.portnum,
 			    REG_FIELD(regs, regnum), REG_FIELD(regs, data_low),
 			    datah_str);
 	}
diff --git a/drivers/dahdi/xpp/xproto.c b/drivers/dahdi/xpp/xproto.c
index a977c8c..4e977c4 100644
--- a/drivers/dahdi/xpp/xproto.c
+++ b/drivers/dahdi/xpp/xproto.c
@@ -381,17 +381,17 @@ void dump_reg_cmd(const char msg[], bool writing, xbus_t *xbus,
 	char data_buf[MAX_PROC_WRITE];
 
 	/* The size byte is not included */
-	if (regcmd->bytes > sizeof(*regcmd) - 1) {
+	if (regcmd->h.bytes > sizeof(*regcmd) - 1) {
 		PORT_NOTICE(xbus, unit, port,
 			    "%s: %s: Too long: regcmd->bytes = %d\n", __func__,
-			    msg, regcmd->bytes);
+			    msg, regcmd->h.bytes);
 		return;
 	}
-	if (regcmd->is_multibyte) {
+	if (regcmd->h.is_multibyte) {
 		char buf[MAX_PROC_WRITE + 1];
 		int i;
 		int n = 0;
-		size_t len = regcmd->bytes;
+		size_t len = regcmd->h.bytes;
 		const __u8 *p = REG_XDATA(regcmd);
 
 		buf[0] = '\0';
@@ -401,18 +401,18 @@ void dump_reg_cmd(const char msg[], bool writing, xbus_t *xbus,
 		PORT_DBG(REGS, xbus, unit, port,
 			"UNIT-%d PORT-%d: Multibyte(eoframe=%d) "
 			"%s[0..%zd]: %s%s\n",
-			unit, port, regcmd->eoframe, msg, len - 1, buf,
+			unit, port, regcmd->h.eoframe, msg, len - 1, buf,
 			(n >= MAX_PROC_WRITE) ? "..." : "");
 		return;
 	}
 	/* The size byte is not included */
-	if (regcmd->bytes != sizeof(*regcmd) - 1) {
+	if (regcmd->h.bytes != REG_CMD_SIZE(REG)) {
 		PORT_NOTICE(xbus, unit, port,
 			    "%s: %s: Wrong size: regcmd->bytes = %d\n",
-			    __func__, msg, regcmd->bytes);
+			    __func__, msg, regcmd->h.bytes);
 		return;
 	}
-	snprintf(port_buf, MAX_PROC_WRITE, "%d%s", regcmd->portnum,
+	snprintf(port_buf, MAX_PROC_WRITE, "%d%s", regcmd->h.portnum,
 		 (REG_FIELD(regcmd, all_ports_broadcast)) ? "*" : "");
 	action = (REG_FIELD(regcmd, read_request)) ? 'R' : 'W';
 	modifier = 'D';
diff --git a/drivers/dahdi/xpp/xproto.h b/drivers/dahdi/xpp/xproto.h
index 321dd81..f88b4ed 100644
--- a/drivers/dahdi/xpp/xproto.h
+++ b/drivers/dahdi/xpp/xproto.h
@@ -167,23 +167,30 @@ bool valid_xpd_addr(const struct xpd_addr *addr);
 
 #define	MULTIBYTE_MAX_LEN	5	/* FPGA firmware limitation */
 
-typedef struct reg_cmd {
+struct reg_cmd_header {
 	__u8 bytes:3;		/* Length (for Multibyte)       */
 	__u8 eoframe:1;		/* For BRI -- end of frame      */
 	__u8 portnum:3;		/* For port specific registers  */
 	__u8 is_multibyte:1;
+} PACKED;
+
+struct reg_cmd_REG {
+	__u8 reserved:3;
+	__u8 do_expander:1;
+	__u8 do_datah:1;
+	__u8 do_subreg:1;
+	__u8 read_request:1;
+	__u8 all_ports_broadcast:1;
+	__u8 regnum;
+	__u8 subreg;
+	__u8 data_low;
+	__u8 data_high;
+} PACKED;
+
+typedef struct reg_cmd {
+	struct reg_cmd_header h;
 	union {
-		struct {
-			__u8 reserved:4;
-			__u8 do_datah:1;
-			__u8 do_subreg:1;
-			__u8 read_request:1;
-			__u8 all_ports_broadcast:1;
-			__u8 regnum;
-			__u8 subreg;
-			__u8 data_low;
-			__u8 data_high;
-		} PACKED r;
+		struct reg_cmd_REG r;
 		/* For Write-Multibyte commands in BRI */
 		struct {
 			__u8 xdata[MULTIBYTE_MAX_LEN];
@@ -192,6 +199,7 @@ typedef struct reg_cmd {
 } PACKED reg_cmd_t;
 
 /* Shortcut access macros */
+#define	REG_CMD_SIZE(variant)		(sizeof(struct reg_cmd_ ## variant))
 #define	REG_FIELD(regptr, member)	((regptr)->alt.r.member)
 #define	REG_XDATA(regptr)		((regptr)->alt.d.xdata)