laden/

2003-09-19  Marcus Brinkmann  <marcus@gnu.org>

	* Makefile.am (laden_CFLAGS): Add -I$(top_srcdir)/libc-parts.
	* output.c: Include <stdlib.h> and <string.h>.
	* output.h (struct output_driver): Add CFG argument to INIT
	function.
	(output_init): Make NAME argument const, rename it to DRIVER.
	* output.c (output_init): Likewise.  Only check if the prefix of
	DRIVER is a driver name.  Then skip a trailing comma and pass the
	remainder via the new variable DRIVER_CFG to the init function of
	the driver.
	* output-vga.c (vga_init): Add CFG argument.
	* output-serial.c: New file by Daniel Wagner <wagi@gmx.de>.

wortel/
2003-09-19  Marcus Brinkmann  <marcus@gnu.org>

	* Makefile.am (wortel_CFLAGS): Add -I$(top_srcdir)/libc-parts.
	* output.c: Include <stdlib.h> and <string.h>.
	* output.h (struct output_driver): Add CFG argument to INIT
	function.
	(output_init): Make NAME argument const, rename it to DRIVER.
	* output.c (output_init): Likewise.  Only check if the prefix of
	DRIVER is a driver name.  Then skip a trailing comma and pass the
	remainder via the new variable DRIVER_CFG to the init function of
	the driver.
	* output-vga.c (vga_init): Add CFG argument.
	* output-serial.c: New file by Daniel Wagner <wagi@gmx.de>.

17 files changed, 454 insertions, 31 deletions

diff --git a/AUTHORS b/AUTHORS
index 4251ca2..ce60489 100644
--- a/AUTHORS
+++ b/AUTHORS
@@ -7,3 +7,7 @@ Johan Rydberg  <jrydberg@night.trouble.net>
 The zone allocator physmem/zalloc.h, physmem/zalloc.c was originally
 written by:
 Neal H Walfield <neal@walfield.org>
+
+The serial output driver for laden and wortel (laden/output-serial.c,
+wortel/output-serial.c) was written by:
+Daniel Wagner <wagi@gmx.ch>
diff --git a/laden/ChangeLog b/laden/ChangeLog
index fbbd212..2568a5a 100644
--- a/laden/ChangeLog
+++ b/laden/ChangeLog
@@ -1,3 +1,17 @@
+2003-09-19  Marcus Brinkmann  <marcus@gnu.org>
+
+	* Makefile.am (laden_CFLAGS): Add -I$(top_srcdir)/libc-parts.
+	* output.c: Include <stdlib.h> and <string.h>.
+	* output.h (struct output_driver): Add CFG argument to INIT
+	function.
+	(output_init): Make NAME argument const, rename it to DRIVER.
+	* output.c (output_init): Likewise.  Only check if the prefix of
+	DRIVER is a driver name.  Then skip a trailing comma and pass the
+	remainder via the new variable DRIVER_CFG to the init function of
+	the driver.
+	* output-vga.c (vga_init): Add CFG argument.
+	* output-serial.c: New file by Daniel Wagner <wagi@gmx.de>.
+
 2003-07-26  Marcus Brinkmann  <marcus@gnu.org>
 
 	* Initial check-in.
diff --git a/laden/Makefile.am b/laden/Makefile.am
index 4c9e9a1..09d1048 100644
--- a/laden/Makefile.am
+++ b/laden/Makefile.am
@@ -20,12 +20,13 @@
 
 if ARCH_IA32
   ARCH_SOURCES = multiboot.h ia32-crt0.S ia32-cmain.c \
-    ia32-output.c output-vga.c ia32-shutdown.c
+    ia32-output.c output-vga.c output-serial.c ia32-shutdown.c
 endif
 
 noinst_PROGRAMS = laden
 
-laden_CFLAGS = -I$(srcdir) -I$(top_srcdir)/include $(AM_CFLAGS)
+laden_CFLAGS = -I$(srcdir) -I$(top_srcdir)/include \
+	-I$(top_srcdir)/libc-parts $(AM_CFLAGS)
 
 laden_SOURCES =  $(ARCH_SOURCES)				\
 	output.h output.c output-none.c				\
diff --git a/laden/README b/laden/README
index 945ebe1..da490f4 100644
--- a/laden/README
+++ b/laden/README
@@ -35,6 +35,23 @@ The available output drivers are architecture specific (see below for
 details).  You can suppress all output by using the output driver
 "none", which is available on all architectures.
 
+Some drivers support options.  You list the options you want to use
+directly following the driver name, separated by commas.  For example,
+to specify COM2 and a baud rate of 9600, you would use the option "-o
+serial,uart2,speed=9600".  Note that spaces are not allowed (as spaces
+separate the arguments to laden).  Which options are recognized
+depends on the driver.
+
+Serial output
+-------------
+
+The serial output driver supports options to configure the serial
+port.  The following options are recognized:
+
+uart1       Select UART1 (aka COM1).
+uart2       Select UART2 (aka COM2).
+speed=BAUD  Set the baud rate to BAUD.  Possible values are 50 to 115200.
+
 
 Architecture Specific Notes
 ===========================
@@ -51,4 +68,4 @@ addresses so that the programs do not overlap.
 The boot info field in the KIP will be set to the multiboot
 information structure.
 
-On this architecture laden supports VGA output.
+On this architecture, laden supports VGA and serial output.
diff --git a/laden/ia32-output.c b/laden/ia32-output.c
index 88c45cc..f4ad778 100644
--- a/laden/ia32-output.c
+++ b/laden/ia32-output.c
@@ -26,12 +26,14 @@
 
 
 extern struct output_driver vga_output;
+extern struct output_driver serial_output;
 extern struct output_driver no_output;
 
 /* A list of all output drivers, terminated with a null pointer.  */
 struct output_driver *output_drivers[] =
   {
     &vga_output,
+    &serial_output,
     &no_output,
     0
   };
diff --git a/laden/output-serial.c b/laden/output-serial.c
new file mode 100644
index 0000000..9b5e2e7
--- /dev/null
+++ b/laden/output-serial.c
@@ -0,0 +1,158 @@
+/* output-serial.c - A serial port output driver.
+   Copyright (C) 2003 Free Software Foundation, Inc.
+   Written by Daniel Wagner.
+
+   This file is part of the GNU Hurd.
+
+   The GNU Hurd is free software; you can redistribute it and/or
+   modify it under the terms of the GNU General Public License as
+   published by the Free Software Foundation; either version 2, or (at
+   your option) any later version.
+
+   The GNU Hurd is distributed in the hope that it will be useful, but
+   WITHOUT ANY WARRANTY; without even the implied warranty of
+   MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
+   General Public License for more details.
+
+   You should have received a copy of the GNU General Public License
+   along with this program; if not, write to the Free Software
+   Foundation, Inc., 59 Temple Place - Suite 330, Boston, MA  02111, USA. */
+
+#if HAVE_CONFIG_H
+#include <config.h>
+#endif
+
+#include <sys/io.h>
+#include <string.h>
+#include <errno.h>
+
+#include "output.h"
+
+
+/* The base I/O ports for the serial device ports COM1 and COM2.  */
+#define UART1_BASE	0x3f8
+#define UART2_BASE	0x2f8
+
+/* The selected base port.  */
+static unsigned short int uart_base = UART1_BASE;
+
+/* The data register.  */
+#define UART_DR		(uart_base + 0)
+
+/* The interrupt enable and ID registers.  */
+#define UART_IER	(uart_base + 1)
+#define UART_IIR	(uart_base + 2)
+
+/* The line and modem control and status registers.  */
+#define UART_LCR	(uart_base + 3)
+#define UART_MCR	(uart_base + 4)
+#define UART_LSR	(uart_base + 5)
+#define UART_LSR_THRE	(1 << 5)
+#define UART_MSR	(uart_base + 6)
+
+
+/* Baudrate divisor LSB and MSB registers.  */
+#define UART_LSB (uart_base + 0)
+#define UART_MSB (uart_base + 1)
+
+/* The default speed setting.  */
+#define UART_SPEED_MAX		115200
+#define UART_SPEED_MIN		50
+#define UART_SPEED_DEFAULT	UART_SPEED_MAX
+
+
+static void
+serial_init (const char *driver_cfg)
+{
+  static const char delimiters[] = ",";
+  /* Twice the desired UART speed, to allow for .5 values.  */
+  unsigned int uart_speed = 2 * UART_SPEED_DEFAULT;
+  unsigned int divider;
+  volatile int busy_wait_var;
+
+  if (driver_cfg)
+    {      
+      char *cfg = strdupa (driver_cfg);
+      char *token = strtok (cfg, delimiters);
+
+      while (token)
+	{
+	  if (!strcmp (token, "uart1"))
+	    uart_base = UART1_BASE;
+	  if (!strcmp (token, "uart2"))
+	    uart_base = UART2_BASE;
+	  if (!strncmp (token, "speed=", 6))
+	    {
+	      char *tail;
+	      unsigned long new_speed;
+	      
+	      errno = 0;
+	      new_speed = strtoul (&token[6], &tail, 0);
+	      
+	      /* Allow .5 for speeds like 134.5.  */
+	      new_speed <<= 1;
+	      if (tail[0] == '.' && tail[1] == '5')
+		{
+		  new_speed++;
+		  tail += 2;
+		}
+	      if (!errno && !*tail
+		  && new_speed > UART_SPEED_MIN && new_speed < UART_SPEED_MAX)
+		uart_speed = new_speed;
+	    }
+	  token = strtok (NULL, delimiters);
+	}
+    }
+
+  /* Parity bit.  */
+  outb (UART_LCR, 0x80);
+
+  /* FIXME: Wait a bit.  Would be nice to have a real sleep function.  */
+  for (busy_wait_var = 0; busy_wait_var < 1000000; busy_wait_var++);
+
+  /* Set baud rate. */
+  divider = (2 * UART_SPEED_MAX) / uart_speed;
+  outb ((divider >> 0) & 0xff, UART_LSB);
+  outb ((divider >> 8) & 0xff, UART_MSB);
+
+  /* Set 8,N,1.  */
+  outb (0x03, UART_LCR);
+
+  /* Disable interrupts.  */
+  outb (0x00, UART_IER);
+
+  /* Enable FIFOs. */
+  outb (0x07, UART_IIR);
+
+  /* Enable RX interrupts.  */
+  outb (0x01, UART_IER);
+
+  inb (UART_IER);
+  inb (UART_IIR);
+  inb (UART_LCR);
+  inb (UART_MCR);
+  inb (UART_LSR);
+  inb (UART_MSR);
+}
+
+
+static void
+serial_putchar (int chr)
+{
+  while (!(inb (UART_LSR) & UART_LSR_THRE))
+    ;
+
+  outb (chr, UART_DR);
+
+  if (chr == '\n')
+    serial_putchar ('\r');
+}
+
+
+struct output_driver serial_output =
+  {
+    "serial",
+    serial_init,
+    0,			/* deinit */
+    serial_putchar
+  };
diff --git a/laden/output-vga.c b/laden/output-vga.c
index 82234e5..0826618 100644
--- a/laden/output-vga.c
+++ b/laden/output-vga.c
@@ -80,7 +80,7 @@ static char *video;
 
 
 static void
-vga_init (void)
+vga_init (const char *cfg)
 {
   unsigned int pos = vga_get_cursor_pos ();
   col = pos % VGA_COLUMNS;
diff --git a/laden/output.c b/laden/output.c
index 8d40cb1..f6f4a59 100644
--- a/laden/output.c
+++ b/laden/output.c
@@ -22,7 +22,9 @@
 #include <config.h>
 #endif
 
+#include <stdlib.h>
 #include <stdarg.h>
+#include <string.h>
 
 #include "output.h"
 
@@ -40,23 +42,32 @@ static struct output_driver *output;
    putchar or any other output routine.  Returns 0 if NAME is not a
    valid output driver name, otherwise 1 on success.  */
 int
-output_init (char *name)
+output_init (const char *driver)
 {
+  const char *driver_cfg = NULL;
+
   if (output)
     {
       output_deinit ();
       output = 0;
     }
 
-  if (name)
+  if (driver)
     {
       struct output_driver **out = &output_drivers[0];
       while (*out)
 	{
-	  if (!strcmp (name, (*out)->name))
+	  unsigned int name_len = strlen ((*out)->name);
+	  if (!strncmp (driver, (*out)->name, name_len))
 	    {
-	      output = *out;
-	      break;
+	      const char *cfg = driver + name_len;
+	      if (!*cfg || *cfg == ',') 
+		{
+		  if (*cfg)
+		    driver_cfg = cfg + 1;
+		  output = *out;
+		  break;
+		}
 	    }
 	  out++;
 	}
@@ -67,7 +78,7 @@ output_init (char *name)
     output = output_drivers[0];
 
   if (output->init)
-    (*output->init) ();
+    (*output->init) (driver_cfg);
 
   return 1;
 }
@@ -251,6 +262,8 @@ printf (const char *fmt, ...)
 	  break;
 
 	case 'p':
+	  putchar ('0');
+	  putchar ('x');
 	  print_nr ((unsigned int) va_arg (ap, void *), 16);
 	  p++;
 	  break;
diff --git a/laden/output.h b/laden/output.h
index c8d1e24..5ab13fa 100644
--- a/laden/output.h
+++ b/laden/output.h
@@ -31,7 +31,7 @@ struct output_driver
   const char *name;
 
   /* Initialize the output device.  */
-  void (*init) (void);
+  void (*init) (const char *cfg);
 
   /* Deinitialize the output device.  */
   void (*deinit) (void);
@@ -47,16 +47,20 @@ struct output_driver
 extern struct output_driver *output_drivers[];
 
 
-/* Activate the output driver NAME or the default one if NAME is a
+/* Activate the output driver DRIVER or the default one if DRIVER is a
    null pointer.  Must be called once at startup, before calling
-   putchar or any other output routine.  Returns 0 if NAME is not a
-   valid output driver name, otherwise 1 on success.  */
-int output_init (char *name);
+   putchar or any other output routine.  DRIVER has the pattern
+   NAME[,CONFIG...], for example "serial,uart2,speed=9600".  Returns 0
+   if DRIVER is not a valid output driver specification, otherwise 1
+   on success.  */
+int output_init (const char *driver);
+
 
 /* Deactivate the output driver.  Must be called after the last time
    putchar or any other output routine is called.  */
 void output_deinit (void);
 
+
 /* Print the single character CHR on the output device.  */
 int putchar (int chr);
 
@@ -67,6 +71,7 @@ int printf (const char *fmt, ...);
 /* True if debug mode is enabled.  */
 extern int output_debug;
 
+
 /* Print a debug message.  */
 #define debug(...) do { if (output_debug) printf (__VA_ARGS__); } while (0)
 
diff --git a/physmem/zalloc.c b/physmem/zalloc.c
index e03e7ac..4f2acd4 100644
--- a/physmem/zalloc.c
+++ b/physmem/zalloc.c
@@ -205,8 +205,6 @@ zfree (l4_word_t block, l4_word_t size)
 			      ? block_align : size_align)
 	- L4_MIN_PAGE_SHIFT;
 
-      printf ("block align: %u  size_align: %u  zone_nr: %u\n",
-	      block_align, size_align, zone_nr);
       add_block ((struct block *) block, zone_nr);
 
       block += ZONE_SIZE (zone_nr);
diff --git a/wortel/Makefile.am b/wortel/Makefile.am
index 48d8f72..4dffa96 100644
--- a/wortel/Makefile.am
+++ b/wortel/Makefile.am
@@ -20,12 +20,13 @@
 
 if ARCH_IA32
   ARCH_SOURCES = multiboot.h ia32-crt0.S ia32-cmain.c \
-    ia32-output.c output-vga.c ia32-shutdown.c
+    ia32-output.c output-vga.c output-serial.c ia32-shutdown.c
 endif
 
 noinst_PROGRAMS = wortel
 
-wortel_CFLAGS = -I$(srcdir) -I$(top_srcdir)/include $(AM_CFLAGS)
+wortel_CFLAGS = -I$(srcdir) -I$(top_srcdir)/include \
+	-I$(top_srcdir)/libc-parts $(AM_CFLAGS)
 
 wortel_SOURCES = $(ARCH_SOURCES)				\
 	output.h output.c output-none.c				\
diff --git a/wortel/README b/wortel/README
index 6dc0af8..9601417 100644
--- a/wortel/README
+++ b/wortel/README
@@ -7,3 +7,37 @@ booting up the system and wrapping privileged L4 operations.
 For now, only a rudimentary part of the loader is written, and the
 only useful thing wortel can do is to start the dummy physmem server
 for a small demonstration.
+
+
+OUTPUT
+======
+
+The available output drivers are architecture specific (see below for
+details).  You can suppress all output by using the output driver
+"none", which is available on all architectures.
+
+Some drivers support options.  You list the options you want to use
+directly following the driver name, separated by commas.  For example,
+to specify COM2 and a baud rate of 9600, you would use the option "-o
+serial,uart2,speed=9600".  Note that spaces are not allowed (as spaces
+separate the arguments to wortel).  Which options are recognized
+depends on the driver.
+
+Serial output
+-------------
+
+The serial output driver supports options to configure the serial
+port.  The following options are recognized:
+
+uart1       Select UART1 (aka COM1).
+uart2       Select UART2 (aka COM2).
+speed=BAUD  Set the baud rate to BAUD.  Possible values are 50 to 115200.
+
+
+Architecture Specific Notes
+===========================
+
+ia32
+----
+
+On this architecture, wortel supports VGA and serial output.
diff --git a/wortel/ia32-output.c b/wortel/ia32-output.c
index 88c45cc..f4ad778 100644
--- a/wortel/ia32-output.c
+++ b/wortel/ia32-output.c
@@ -26,12 +26,14 @@
 
 
 extern struct output_driver vga_output;
+extern struct output_driver serial_output;
 extern struct output_driver no_output;
 
 /* A list of all output drivers, terminated with a null pointer.  */
 struct output_driver *output_drivers[] =
   {
     &vga_output,
+    &serial_output,
     &no_output,
     0
   };
diff --git a/wortel/output-serial.c b/wortel/output-serial.c
new file mode 100644
index 0000000..91c6914
--- /dev/null
+++ b/wortel/output-serial.c
@@ -0,0 +1,159 @@
+/* output-serial.c - A serial port output driver.
+   Copyright (C) 2003 Free Software Foundation, Inc.
+   Written by Daniel Wagner.
+
+   This file is part of the GNU Hurd.
+
+   The GNU Hurd is free software; you can redistribute it and/or
+   modify it under the terms of the GNU General Public License as
+   published by the Free Software Foundation; either version 2, or (at
+   your option) any later version.
+
+   The GNU Hurd is distributed in the hope that it will be useful, but
+   WITHOUT ANY WARRANTY; without even the implied warranty of
+   MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
+   General Public License for more details.
+
+   You should have received a copy of the GNU General Public License
+   along with this program; if not, write to the Free Software
+   Foundation, Inc., 59 Temple Place - Suite 330, Boston, MA  02111, USA. */
+
+#if HAVE_CONFIG_H
+#include <config.h>
+#endif
+
+#include <sys/io.h>
+#include <string.h>
+#include <errno.h>
+
+#include <l4/ipc.h>
+
+#include "output.h"
+
+
+/* The base I/O ports for the serial device ports COM1 and COM2.  */
+#define UART1_BASE	0x3f8
+#define UART2_BASE	0x2f8
+
+/* The selected base port.  */
+static unsigned short int uart_base = UART1_BASE;
+
+/* The data register.  */
+#define UART_DR		(uart_base + 0)
+
+/* The interrupt enable and ID registers.  */
+#define UART_IER	(uart_base + 1)
+#define UART_IIR	(uart_base + 2)
+
+/* The line and modem control and status registers.  */
+#define UART_LCR	(uart_base + 3)
+#define UART_MCR	(uart_base + 4)
+#define UART_LSR	(uart_base + 5)
+#define UART_LSR_THRE	(1 << 5)
+#define UART_MSR	(uart_base + 6)
+
+
+/* Baudrate divisor LSB and MSB registers.  */
+#define UART_LSB (uart_base + 0)
+#define UART_MSB (uart_base + 1)
+
+/* The default speed setting.  */
+#define UART_SPEED_MAX		115200
+#define UART_SPEED_MIN		50
+#define UART_SPEED_DEFAULT	UART_SPEED_MAX
+
+
+static void
+serial_init (const char *driver_cfg)
+{
+  static const char delimiters[] = ",";
+  /* Twice the desired UART speed, to allow for .5 values.  */
+  unsigned int uart_speed = 2 * UART_SPEED_DEFAULT;
+  unsigned int divider;
+
+  if (driver_cfg)
+    {      
+      char *cfg = strdupa (driver_cfg);
+      char *token = strtok (cfg, delimiters);
+
+      while (token)
+	{
+	  if (!strcmp (token, "uart1"))
+	    uart_base = UART1_BASE;
+	  if (!strcmp (token, "uart2"))
+	    uart_base = UART2_BASE;
+	  if (!strncmp (token, "speed=", 6))
+	    {
+	      char *tail;
+	      unsigned long new_speed;
+	      
+	      errno = 0;
+	      new_speed = strtoul (&token[6], &tail, 0);
+	      
+	      /* Allow .5 for speeds like 134.5.  */
+	      new_speed <<= 1;
+	      if (tail[0] == '.' && tail[1] == '5')
+		{
+		  new_speed++;
+		  tail += 2;
+		}
+	      if (!errno && !*tail
+		  && new_speed > UART_SPEED_MIN && new_speed < UART_SPEED_MAX)
+		uart_speed = new_speed;
+	    }
+	  token = strtok (NULL, delimiters);
+	}
+    }
+
+  /* Parity bit.  */
+  outb (UART_LCR, 0x80);
+
+  /* FIXME: How long do we have to wait? */
+  l4_sleep (l4_time_period (L4_WORD_C (100000)));
+
+  /* Set baud rate. */
+  divider = (2 * UART_SPEED_MAX) / uart_speed;
+  outb ((divider >> 0) & 0xff, UART_LSB);
+  outb ((divider >> 8) & 0xff, UART_MSB);
+
+  /* Set 8,N,1.  */
+  outb (0x03, UART_LCR);
+
+  /* Disable interrupts.  */
+  outb (0x00, UART_IER);
+
+  /* Enable FIFOs. */
+  outb (0x07, UART_IIR);
+
+  /* Enable RX interrupts.  */
+  outb (0x01, UART_IER);
+
+  inb (UART_IER);
+  inb (UART_IIR);
+  inb (UART_LCR);
+  inb (UART_MCR);
+  inb (UART_LSR);
+  inb (UART_MSR);
+}
+
+
+static void
+serial_putchar (int chr)
+{
+  while (!(inb (UART_LSR) & UART_LSR_THRE))
+    ;
+
+  outb (chr, UART_DR);
+
+  if (chr == '\n')
+    serial_putchar ('\r');
+}
+
+
+struct output_driver serial_output =
+  {
+    "serial",
+    serial_init,
+    0,			/* deinit */
+    serial_putchar
+  };
diff --git a/wortel/output-vga.c b/wortel/output-vga.c
index 82234e5..0826618 100644
--- a/wortel/output-vga.c
+++ b/wortel/output-vga.c
@@ -80,7 +80,7 @@ static char *video;
 
 
 static void
-vga_init (void)
+vga_init (const char *cfg)
 {
   unsigned int pos = vga_get_cursor_pos ();
   col = pos % VGA_COLUMNS;
diff --git a/wortel/output.c b/wortel/output.c
index 1da9826..f6f4a59 100644
--- a/wortel/output.c
+++ b/wortel/output.c
@@ -22,6 +22,7 @@
 #include <config.h>
 #endif
 
+#include <stdlib.h>
 #include <stdarg.h>
 #include <string.h>
 
@@ -41,23 +42,32 @@ static struct output_driver *output;
    putchar or any other output routine.  Returns 0 if NAME is not a
    valid output driver name, otherwise 1 on success.  */
 int
-output_init (char *name)
+output_init (const char *driver)
 {
+  const char *driver_cfg = NULL;
+
   if (output)
     {
       output_deinit ();
       output = 0;
     }
 
-  if (name)
+  if (driver)
     {
       struct output_driver **out = &output_drivers[0];
       while (*out)
 	{
-	  if (!strcmp (name, (*out)->name))
+	  unsigned int name_len = strlen ((*out)->name);
+	  if (!strncmp (driver, (*out)->name, name_len))
 	    {
-	      output = *out;
-	      break;
+	      const char *cfg = driver + name_len;
+	      if (!*cfg || *cfg == ',') 
+		{
+		  if (*cfg)
+		    driver_cfg = cfg + 1;
+		  output = *out;
+		  break;
+		}
 	    }
 	  out++;
 	}
@@ -68,7 +78,7 @@ output_init (char *name)
     output = output_drivers[0];
 
   if (output->init)
-    (*output->init) ();
+    (*output->init) (driver_cfg);
 
   return 1;
 }
diff --git a/wortel/output.h b/wortel/output.h
index c8d1e24..5ab13fa 100644
--- a/wortel/output.h
+++ b/wortel/output.h
@@ -31,7 +31,7 @@ struct output_driver
   const char *name;
 
   /* Initialize the output device.  */
-  void (*init) (void);
+  void (*init) (const char *cfg);
 
   /* Deinitialize the output device.  */
   void (*deinit) (void);
@@ -47,16 +47,20 @@ struct output_driver
 extern struct output_driver *output_drivers[];
 
 
-/* Activate the output driver NAME or the default one if NAME is a
+/* Activate the output driver DRIVER or the default one if DRIVER is a
    null pointer.  Must be called once at startup, before calling
-   putchar or any other output routine.  Returns 0 if NAME is not a
-   valid output driver name, otherwise 1 on success.  */
-int output_init (char *name);
+   putchar or any other output routine.  DRIVER has the pattern
+   NAME[,CONFIG...], for example "serial,uart2,speed=9600".  Returns 0
+   if DRIVER is not a valid output driver specification, otherwise 1
+   on success.  */
+int output_init (const char *driver);
+
 
 /* Deactivate the output driver.  Must be called after the last time
    putchar or any other output routine is called.  */
 void output_deinit (void);
 
+
 /* Print the single character CHR on the output device.  */
 int putchar (int chr);
 
@@ -67,6 +71,7 @@ int printf (const char *fmt, ...);
 /* True if debug mode is enabled.  */
 extern int output_debug;
 
+
 /* Print a debug message.  */
 #define debug(...) do { if (output_debug) printf (__VA_ARGS__); } while (0)