diff --git a/sys/alpha/alpha/alpha-gdbstub.c b/sys/alpha/alpha/alpha-gdbstub.c
index f011ed7d36a0..9e3dedb4e1e7 100644
--- a/sys/alpha/alpha/alpha-gdbstub.c
+++ b/sys/alpha/alpha/alpha-gdbstub.c
@@ -153,18 +153,18 @@ strcpy (char *dst, const char *src)
 static int
 putDebugChar (int c)		/* write a single character      */
 {
-  if (gdbdev == NODEV)
+  if (gdb_arg == NULL)
 	return 0;
-  (*gdb_putc)(gdbdev, c);
+  (*gdb_putc)(gdb_arg, c);
   return 1;
 }
 
 static int
 getDebugChar (void)		/* read and return a single char */
 {
-  if (gdbdev == NODEV)
+  if (gdb_arg == NULL)
 	return -1;
-  return (*gdb_getc)(gdbdev);
+  return (*gdb_getc)(gdb_arg);
 }
 
 static const char hexchars[]="0123456789abcdef";
@@ -625,7 +625,7 @@ gdb_handle_exception (db_regs_t *raw_regs, int type, int code)
 
   while (1)
     {
-      if (gdbdev == NODEV)	/* somebody's removed it */
+      if (gdb_arg == NULL)	/* somebody's removed it */
 	return;			/* get out of here */
       remcomOutBuffer[0] = 0;
 
diff --git a/sys/amd64/amd64/amd64-gdbstub.c b/sys/amd64/amd64/amd64-gdbstub.c
index fd283bd96f9a..0ea0a24c6740 100644
--- a/sys/amd64/amd64/amd64-gdbstub.c
+++ b/sys/amd64/amd64/amd64-gdbstub.c
@@ -146,18 +146,18 @@ strcpy (char *dst, const char *src)
 static int
 putDebugChar (int c)		/* write a single character      */
 {
-  if (gdbdev == NODEV)
+  if (gdb_arg == NULL)
 	return 0;
-  (*gdb_putc)(gdbdev, c);
+  (*gdb_putc)(gdb_arg, c);
   return 1;
 }
 
 static int
 getDebugChar (void)		/* read and return a single char */
 {
-  if (gdbdev == NODEV)
+  if (gdb_arg == NULL)
 	return -1;
-  return (*gdb_getc)(gdbdev);
+  return (*gdb_getc)(gdb_arg);
 }
 
 static const char hexchars[]="0123456789abcdef";
@@ -487,7 +487,7 @@ gdb_handle_exception (db_regs_t *raw_regs, int type, int code)
 
   while (1)
     {
-      if (gdbdev == NODEV)
+      if (gdb_arg == NULL)
 	return 1;		/* somebody has removed the gdb device */
       remcomOutBuffer[0] = 0;
 
diff --git a/sys/ddb/db_command.c b/sys/ddb/db_command.c
index f0aa6d2ad01c..ab58bc2feeda 100644
--- a/sys/ddb/db_command.c
+++ b/sys/ddb/db_command.c
@@ -550,7 +550,7 @@ db_fncall(dummy1, dummy2, dummy3, dummy4)
 
 /* Enter GDB remote protocol debugger on the next trap. */
 
-dev_t	   gdbdev = NODEV;
+void	  *gdb_arg = NULL;
 cn_getc_t *gdb_getc;
 cn_putc_t *gdb_putc;
 
@@ -562,7 +562,7 @@ db_gdb (dummy1, dummy2, dummy3, dummy4)
 	char *		dummy4;
 {
 
-	if (gdbdev == NODEV) {
+	if (gdb_arg == NULL) {
 		db_printf("No gdb port enabled. Set flag 0x80 on desired port\n");
 		db_printf("in your configuration file (currently sio only).\n");
 		return;
diff --git a/sys/ddb/ddb.h b/sys/ddb/ddb.h
index 3124c6e8f393..7259e97b6637 100644
--- a/sys/ddb/ddb.h
+++ b/sys/ddb/ddb.h
@@ -161,7 +161,7 @@ struct command {
 /*
  * Routines to support GDB on an sio port.
  */
-extern dev_t	   gdbdev;
+extern void	 *gdb_arg;
 extern cn_getc_t *gdb_getc;
 extern cn_putc_t *gdb_putc;
 #endif
diff --git a/sys/dev/sio/sio.c b/sys/dev/sio/sio.c
index 1ca84d45dae7..7efb6689ab1b 100644
--- a/sys/dev/sio/sio.c
+++ b/sys/dev/sio/sio.c
@@ -2982,7 +2982,7 @@ siocnprobe(cp)
 				siogdbiobase = iobase;
 				siogdbunit = unit;
 #if DDB > 0
-				gdbdev = makedev(CDEV_MAJOR, unit);
+				gdb_arg = makedev(CDEV_MAJOR, unit);
 				gdb_getc = siocngetc;
 				gdb_putc = siocnputc;
 #endif
@@ -2996,14 +2996,14 @@ siocnprobe(cp)
 	 * If no gdb port has been specified, set it to be the console
 	 * as some configuration files don't specify the gdb port.
 	 */
-	if (gdbdev == NODEV && (boothowto & RB_GDB)) {
+	if (gdb_arg == NULL && (boothowto & RB_GDB)) {
 		printf("Warning: no GDB port specified. Defaulting to sio%d.\n",
 			siocnunit);
 		printf("Set flag 0x80 on desired GDB port in your\n");
 		printf("configuration file (currently sio only).\n");
 		siogdbiobase = siocniobase;
 		siogdbunit = siocnunit;
-		gdbdev = makedev(CDEV_MAJOR, siocnunit);
+		gdb_arg = makedev(CDEV_MAJOR, siocnunit);
 		gdb_getc = siocngetc;
 		gdb_putc = siocnputc;
 	}
@@ -3090,7 +3090,7 @@ siogdbattach(port, speed)
 	printf("sio%d: gdb debugging port\n", unit);
 	siogdbunit = unit;
 #if DDB > 0
-	gdbdev = makedev(CDEV_MAJOR, unit);
+	gdb_arg = makedev(CDEV_MAJOR, unit);
 	gdb_getc = siocngetc;
 	gdb_putc = siocnputc;
 #endif
diff --git a/sys/i386/i386/i386-gdbstub.c b/sys/i386/i386/i386-gdbstub.c
index fd283bd96f9a..0ea0a24c6740 100644
--- a/sys/i386/i386/i386-gdbstub.c
+++ b/sys/i386/i386/i386-gdbstub.c
@@ -146,18 +146,18 @@ strcpy (char *dst, const char *src)
 static int
 putDebugChar (int c)		/* write a single character      */
 {
-  if (gdbdev == NODEV)
+  if (gdb_arg == NULL)
 	return 0;
-  (*gdb_putc)(gdbdev, c);
+  (*gdb_putc)(gdb_arg, c);
   return 1;
 }
 
 static int
 getDebugChar (void)		/* read and return a single char */
 {
-  if (gdbdev == NODEV)
+  if (gdb_arg == NULL)
 	return -1;
-  return (*gdb_getc)(gdbdev);
+  return (*gdb_getc)(gdb_arg);
 }
 
 static const char hexchars[]="0123456789abcdef";
@@ -487,7 +487,7 @@ gdb_handle_exception (db_regs_t *raw_regs, int type, int code)
 
   while (1)
     {
-      if (gdbdev == NODEV)
+      if (gdb_arg == NULL)
 	return 1;		/* somebody has removed the gdb device */
       remcomOutBuffer[0] = 0;
 
diff --git a/sys/pc98/cbus/sio.c b/sys/pc98/cbus/sio.c
index 675e22d34932..7d497dbca944 100644
--- a/sys/pc98/cbus/sio.c
+++ b/sys/pc98/cbus/sio.c
@@ -4212,7 +4212,7 @@ siocnprobe(cp)
 				siogdbiobase = iobase;
 				siogdbunit = unit;
 #if DDB > 0
-				gdbdev = makedev(CDEV_MAJOR, unit);
+				gdb_arg = makedev(CDEV_MAJOR, unit);
 				gdb_getc = siocngetc;
 				gdb_putc = siocnputc;
 #endif
@@ -4226,14 +4226,14 @@ siocnprobe(cp)
 	 * If no gdb port has been specified, set it to be the console
 	 * as some configuration files don't specify the gdb port.
 	 */
-	if (gdbdev == NODEV && (boothowto & RB_GDB)) {
+	if (gdb_arg == NULL && (boothowto & RB_GDB)) {
 		printf("Warning: no GDB port specified. Defaulting to sio%d.\n",
 			siocnunit);
 		printf("Set flag 0x80 on desired GDB port in your\n");
 		printf("configuration file (currently sio only).\n");
 		siogdbiobase = siocniobase;
 		siogdbunit = siocnunit;
-		gdbdev = makedev(CDEV_MAJOR, siocnunit);
+		gdb_arg = makedev(CDEV_MAJOR, siocnunit);
 		gdb_getc = siocngetc;
 		gdb_putc = siocnputc;
 	}
@@ -4320,7 +4320,7 @@ siogdbattach(port, speed)
 	printf("sio%d: gdb debugging port\n", unit);
 	siogdbunit = unit;
 #if DDB > 0
-	gdbdev = makedev(CDEV_MAJOR, unit);
+	gdb_arg = makedev(CDEV_MAJOR, unit);
 	gdb_getc = siocngetc;
 	gdb_putc = siocnputc;
 #endif
diff --git a/sys/pc98/pc98/sio.c b/sys/pc98/pc98/sio.c
index 675e22d34932..7d497dbca944 100644
--- a/sys/pc98/pc98/sio.c
+++ b/sys/pc98/pc98/sio.c
@@ -4212,7 +4212,7 @@ siocnprobe(cp)
 				siogdbiobase = iobase;
 				siogdbunit = unit;
 #if DDB > 0
-				gdbdev = makedev(CDEV_MAJOR, unit);
+				gdb_arg = makedev(CDEV_MAJOR, unit);
 				gdb_getc = siocngetc;
 				gdb_putc = siocnputc;
 #endif
@@ -4226,14 +4226,14 @@ siocnprobe(cp)
 	 * If no gdb port has been specified, set it to be the console
 	 * as some configuration files don't specify the gdb port.
 	 */
-	if (gdbdev == NODEV && (boothowto & RB_GDB)) {
+	if (gdb_arg == NULL && (boothowto & RB_GDB)) {
 		printf("Warning: no GDB port specified. Defaulting to sio%d.\n",
 			siocnunit);
 		printf("Set flag 0x80 on desired GDB port in your\n");
 		printf("configuration file (currently sio only).\n");
 		siogdbiobase = siocniobase;
 		siogdbunit = siocnunit;
-		gdbdev = makedev(CDEV_MAJOR, siocnunit);
+		gdb_arg = makedev(CDEV_MAJOR, siocnunit);
 		gdb_getc = siocngetc;
 		gdb_putc = siocnputc;
 	}
@@ -4320,7 +4320,7 @@ siogdbattach(port, speed)
 	printf("sio%d: gdb debugging port\n", unit);
 	siogdbunit = unit;
 #if DDB > 0
-	gdbdev = makedev(CDEV_MAJOR, unit);
+	gdb_arg = makedev(CDEV_MAJOR, unit);
 	gdb_getc = siocngetc;
 	gdb_putc = siocnputc;
 #endif