This allows you to specify "dsscon=true" in the boot parameters,
similar to what you can do for the 2.4 kernels.

I have not tried a kernel with xmon using this enabled.

 - todd <Todd.Miller@courtesan.com>

--- ../linux-2.1.DIST/arch/ppc/tcd/setup.c	Fri May 31 16:28:13 2002
+++ arch/ppc/tcd/setup.c	Fri Oct  3 15:11:35 2003
@@ -65,6 +65,7 @@
 
 extern int root_mountflags;
 static int cpuclock;
+int dsscon;
 
 void do_unblank_screen(void);
 void hard_reset_now(void);
@@ -132,6 +133,7 @@
 	extern void register_console(void (*)(const char *));
 	unsigned int iocr;
 	unsigned int br;
+	char *cp;
 
 	/* HACK: check for first 5 chars == Root=.  If so, rewrite root= and
 	   disable console */
@@ -141,6 +143,9 @@
 		saved_boot_params[0] = 'r';
 		s403_ready = -1;
 	}
+	/* must check for dsscon before initializing the s403 */
+	if ((cp = strstr(saved_boot_params, "dsscon=")))
+		dsscon = strncmp(cp, "true", 4);
 #if 1
 	s403_virtualinit();
 	register_console(s403_print);
--- ../linux-2.1.DIST/arch/ppc/tcd/403serial.c	Fri May 31 16:28:13 2002
+++ arch/ppc/tcd/403serial.c	Fri Oct  3 14:48:34 2003
@@ -16,21 +16,27 @@
 {
         __asm__( "eieio " : : );
 }
-static volatile unsigned char *S403_BASE = (volatile unsigned char *) IOBASE_UART;
+static volatile unsigned char *S403_BASE;
 
 int	s403_ready = 0;
 
 void
 s403_virtualinit(void) {
+	extern int dsscon;
+
 	s403_ready = 0;
-	S403_BASE = (volatile unsigned char *)IOBASE_UART;
+	S403_BASE = dsscon ? (volatile unsigned char *)IOBASE_DSSUART :
+	    (volatile unsigned char *)IOBASE_UART;
 	s403_init();
 }
 
 void
 s403_realinit(void) {
+	extern int dsscon;
+
 	s403_ready = 0;
-	S403_BASE = (volatile unsigned char *) IOBASE_UART;
+	S403_BASE = dsscon ? (volatile unsigned char *)IOBASE_DSSUART :
+	    (volatile unsigned char *)IOBASE_UART;
 	s403_init();
 }
 
--- ../linux-2.1.DIST/drivers/char/serial.c	Fri May 31 16:28:14 2002
+++ drivers/char/serial.c	Fri Oct  3 14:50:03 2003
@@ -3704,6 +3708,7 @@
     unsigned char status1, status2, scratch, scratch2;
     struct async_struct *info, scr_info;
     unsigned long flags;
+    extern int dsscon;
 
     state->type = PORT_UNKNOWN;
 	
@@ -3721,16 +3726,18 @@
 #ifdef SERIAL_DEBUG_OPEN
     printk("autoconfig, port=0x%x, irq=%d\n", state->port, state->irq);
 #endif
-    if (state->port == IOBASE_SERIAL) {
-	state->type = PORT_S403;
+    /* XXX - init the 403 console at all when dsscon is spec'd? (millert) */
+    if (state->port == IOBASE_SERIAL || (dsscon && state->port == IOBASE_DSSUART)) {
+	state->type = state->port == IOBASE_SERIAL ? PORT_S403 : PORT_16550A;
 #ifdef SERIAL_DEBUG_OPEN
-	printk("autoconfig, type=403\n");
+	printk("autoconfig, type=%s\n",
+	    state->type == PORT_S403 ? "403" : "16550A");
 #endif
 	/*
 	 * If the AUTO_IRQ flag is set, try to do the automatic IRQ
 	 * detection.
 	 */
-	state->irq = RS_FAKE_S403;
+	state->irq = state->type == PORT_S403 ? RS_FAKE_S403 : RS_FAKE_DSSUART;
 			
 	state->xmit_fifo_size =	uart_config[state->type].dfl_xmit_fifo_size;