Re: [PATCH 1/3] KGDB: Major refactoring

[Maxim Levitsky]

On Wednesday, 6 February 2008 01:34:13 Jan Kiszka wrote:
> As most changes are tightly coupled, this refactoring patch for
> KGDB_8250 as well as the core and the new KGDBOC driver comes as a
> single chunk. The changes are:
>  - Reorganized configuration: I/O drivers can be independently
>    configured as module or built-in
>  - Dynamic reconfiguration for KGDB_8250 (just like for KGDBOC)
>  - Reworked KGDB_8250 configuration string format
>  - attachwait removed, arming the debugger via assigning an I/O driver
>    implies "attachwait"
>  - Cleaned up I/O driver managment of the core
>  - Matured the various boot-up, configure, unconfigure code paths for
>    both I/O drivers
>  - IRQ vs. KGDB_CONSOLE-output SMP race fixed for KGDB_8250
>  - Reduced and cleaned up hooks into serial_core/8250
>  - Kconfig cleanups
> 
> What we no longer have:
>  - Simple serial configuration for _early_ debugging, use the io/mem
>    format instead or wait until the debugger is able to resolve "ttySx"
>    during late-init
> 
> To-do:
>  - KGDBOC does not yet cleanly interacts with the TTY subsystem to
>    attach to some console
> 
> Signed-off-by: Jan Kiszka <jan.kiszka@xxxxxx>
> 
> ---
>  drivers/serial/8250.c        |   56 +--
>  drivers/serial/8250_kgdb.c   |  731 +++++++++++++++++++------------------------
>  drivers/serial/Kconfig       |    3 
>  drivers/serial/kgdboc.c      |  118 ++----
>  drivers/serial/serial_core.c |    6 
>  include/linux/kgdb.h         |   20 -
>  kernel/kgdb.c                |  373 +++++----------------
>  lib/Kconfig.kgdb             |  153 +--------
>  8 files changed, 520 insertions(+), 940 deletions(-)
> 
> Index: b/drivers/serial/8250_kgdb.c
> ===================================================================
> --- a/drivers/serial/8250_kgdb.c
> +++ b/drivers/serial/8250_kgdb.c
> @@ -1,5 +1,5 @@
>  /*
> - * 8250 interface for kgdb.
> + * 8250 serial I/O driver for KGDB.
>   *
>   * This is a merging of many different drivers, and all of the people have
>   * had an impact in some form or another:
> @@ -12,143 +12,100 @@
>   * Robert Walsh <rjwalsh@xxxxxxxxxxxx>, wangdi <wangdi@xxxxxxxxxxxxx>,
>   * San Mehat, Tom Rini <trini@xxxxxxxxxx>,
>   * Jason Wessel <jason.wessel@xxxxxxxxxxxxx>
> + *
> + * Refactoring and cleanup for initial merge:
> + * 2008 (c) Jan Kiszka <jan.kiszka@xxxxxx>
> + *
> + * This file is licensed under the terms of the GNU General Public License
> + * version 2. This program is licensed "as is" without any warranty of any
> + * kind, whether express or implied.
>   */
>  
>  #include <linux/kernel.h>
>  #include <linux/init.h>
>  #include <linux/kgdb.h>
>  #include <linux/interrupt.h>
> -#include <linux/tty.h>
> -#include <linux/serial.h>
>  #include <linux/serial_reg.h>
> -#include <linux/serialP.h>
>  #include <linux/ioport.h>
>  #include <linux/io.h>
> -#include <asm/serial.h>		/* For BASE_BAUD and SERIAL_PORT_DFNS */
> -
> -#include "8250.h"
> -
> -#define GDB_BUF_SIZE	512	/* power of 2, please */
> +#include <linux/ctype.h>
> +#include <asm/serial.h>		/* for BASE_BAUD */
>  
>  MODULE_DESCRIPTION("KGDB driver for the 8250");
>  MODULE_LICENSE("GPL");
> -/* These will conflict with early_param otherwise. */
> -#ifdef CONFIG_KGDB_8250_MODULE
> -static char config[256];
> -module_param_string(kgdb8250, config, 256, 0);
> -MODULE_PARM_DESC(kgdb8250,
> -		 " kgdb8250=<io or mmio>,<address>,<baud rate>,<irq>\n");
> -static struct kgdb_io local_kgdb_io_ops;
> -#endif				/* CONFIG_KGDB_8250_MODULE */
> -
> -#ifdef CONFIG_KGDB_BAUDRATE
> -static int kgdb8250_baud = CONFIG_KGDB_BAUDRATE;
> -#else
> -static int kgdb8250_baud;
> -#endif
> -#ifdef CONFIG_KGDB_PORT_NUM
> -static int kgdb8250_line = CONFIG_KGDB_PORT_NUM;
> -#else
> -static int kgdb8250_line = -1;
> -#endif
> -
> -/* Flag for if we need to call request_mem_region */
> -static int kgdb8250_needs_request_mem_region;
>  
> -static char kgdb8250_buf[GDB_BUF_SIZE];
> -static atomic_t kgdb8250_buf_in_cnt;
> -static int kgdb8250_buf_out_inx;
> -
> -/* Old-style serial definitions, if existant, and a counter. */
> -#ifdef CONFIG_KGDB_SIMPLE_SERIAL
> -static int __initdata should_copy_rs_table = 1;
> -static struct serial_state old_rs_table[] __initdata = {
> -#ifdef SERIAL_PORT_DFNS
> -	SERIAL_PORT_DFNS
> -#endif
> +#define KGD8250_MAX_CONFIG_STR	64
> +static char config[KGD8250_MAX_CONFIG_STR];
> +static struct kparam_string kps = {
> +	.string = config,
> +	.maxlen = KGD8250_MAX_CONFIG_STR,
>  };
> -#endif
>  
> -/* Our internal table of UARTS. */
> -#define UART_NR	CONFIG_SERIAL_8250_NR_UARTS
> -static struct uart_port kgdb8250_ports[UART_NR];
> +static int kgdb8250_baud;
> +static void *kgdb8250_addr;
> +static int kgdb8250_irq = -1;
> +static struct uart_port kgdb8250_port;
>  
> -static struct uart_port *current_port;
> +/* UART port we might have stolen from the 8250 driver */
> +static int hijacked_line;
>  
> -/* Base of the UART. */
> -static void *kgdb8250_addr;
> +static int late_init_passed;
> +static int fully_initialized;
> +static int buffered_char = -1;
> +
> +static struct kgdb_io kgdb8250_io_ops;	/* initialized later */
>  
> -/* Forward declarations. */
>  static int kgdb8250_uart_init(void);
> -static int __init kgdb_init_io(void);
> -static int __init kgdb8250_opt(char *str);
>  
> -/* These are much shorter calls to ioread8/iowrite8 that take into
> - * account our shifts, etc. */
> -static inline unsigned int kgdb_ioread(u8 mask)
> +static inline unsigned int kgdb8250_ioread(u8 mask)
>  {
> -	return ioread8(kgdb8250_addr + (mask << current_port->regshift));
> +	return ioread8(kgdb8250_addr + (mask << kgdb8250_port.regshift));
>  }
>  
> -static inline void kgdb_iowrite(u8 val, u8 mask)
> +static inline void kgdb8250_iowrite(u8 val, u8 mask)
>  {
> -	iowrite8(val, kgdb8250_addr + (mask << current_port->regshift));
> +	iowrite8(val, kgdb8250_addr + (mask << kgdb8250_port.regshift));
>  }
>  
>  /*
>   * Wait until the interface can accept a char, then write it.
>   */
> -static void kgdb_put_debug_char(u8 chr)
> +static void kgdb8250_put_debug_char(u8 chr)
>  {
> -	while (!(kgdb_ioread(UART_LSR) & UART_LSR_THRE)) ;
> +	while (!(kgdb8250_ioread(UART_LSR) & UART_LSR_THRE))
> +		cpu_relax();
>  
> -	kgdb_iowrite(chr, UART_TX);
> +	kgdb8250_iowrite(chr, UART_TX);
>  }
>  
>  /*
> - * Get a byte from the hardware data buffer and return it
> + * Get a byte from the hardware data buffer and return it.
>   */
> -static int read_data_bfr(void)
> +static int kgdb8250_get_debug_char(void)
>  {
> -	char it = kgdb_ioread(UART_LSR);
> +	unsigned int lsr;
>  
> -	if (it & UART_LSR_DR)
> -		return kgdb_ioread(UART_RX);
> +	while (1) {
> +		/* Did the interrupt handler catch something before us? */
> +		if (buffered_char >= 0)
> +			return xchg(&buffered_char, -1);
>  
> -	/*
> -	 * If we have a framing error assume somebody messed with
> -	 * our uart.  Reprogram it and send '-' both ways...
> -	 */
> -	if (it & 0xc) {
> -		kgdb8250_uart_init();
> -		kgdb_put_debug_char('-');
> -		return '-';
> -	}
> +		lsr = kgdb8250_ioread(UART_LSR);
> +		if (lsr & UART_LSR_DR)
> +			return kgdb8250_ioread(UART_RX);
>  
> -	return -1;
> -}
> -
> -/*
> - * Get a char if available, return -1 if nothing available.
> - * Empty the receive buffer first, then look at the interface hardware.
> - */
> -static int kgdb_get_debug_char(void)
> -{
> -	int retchr;
> +		/*
> +		 * If we have a framing error assume somebody messed with
> +		 * our uart.  Reprogram it and send '-' both ways...
> +		 */
> +		if (lsr & (UART_LSR_PE | UART_LSR_FE)) {
> +			kgdb8250_uart_init();
> +			kgdb8250_put_debug_char('-');
> +			return '-';
> +		}
>  
> -	/* intr routine has q'd chars */
> -	if (atomic_read(&kgdb8250_buf_in_cnt) != 0) {
> -		retchr = kgdb8250_buf[kgdb8250_buf_out_inx++];
> -		kgdb8250_buf_out_inx &= (GDB_BUF_SIZE - 1);
> -		atomic_dec(&kgdb8250_buf_in_cnt);
> -		return retchr;
> +		cpu_relax();
>  	}
> -
> -	do {
> -		retchr = read_data_bfr();
> -	} while (retchr < 0);
> -
> -	return retchr;
>  }
>  
>  /*
> @@ -157,77 +114,71 @@ static int kgdb_get_debug_char(void)
>   * line we're in charge of.  If this is true, schedule a breakpoint and
>   * return.
>   */
> -static irqreturn_t
> -kgdb8250_interrupt(int irq, void *dev_id)
> +static irqreturn_t kgdb8250_interrupt(int irq, void *dev_id)
>  {
> -	if (!(kgdb_ioread(UART_IIR) & UART_IIR_RDI))
> -		return IRQ_NONE;
> +	unsigned int iir = kgdb8250_ioread(UART_IIR);
> +	char c;
>  
> -	/* Throw away the data if another I/O routine is active. */
> -	if (kgdb_io_ops.read_char != kgdb_get_debug_char &&
> -	    (kgdb_ioread(UART_LSR) & UART_LSR_DR))
> -		kgdb_ioread(UART_RX);
> -	else
> -		breakpoint();
> +	if (iir & UART_IIR_NO_INT)
> +		return IRQ_NONE;
>  
> +	if ((iir & UART_IIR_ID) == UART_IIR_RDI) {
> +		c = kgdb8250_ioread(UART_RX);
> +		if (c == 0x03)
> +			breakpoint();
> +		else
> +			buffered_char = c;
> +	}
>  	return IRQ_HANDLED;
>  }
>  
>  /*
>   *  Initializes the UART.
>   *  Returns:
> - *	0 on success, 1 on failure.
> + *	0 on success, -errno on failure.
>   */
>  static int kgdb8250_uart_init(void)
>  {
>  	unsigned int ier;
> -	unsigned int base_baud = current_port->uartclk ?
> -		current_port->uartclk / 16 : BASE_BAUD;
> +	unsigned int base_baud = kgdb8250_port.uartclk ?
> +		kgdb8250_port.uartclk / 16 : BASE_BAUD;
>  
> -	/* test uart existance */
> -	if (kgdb_ioread(UART_LSR) == 0xff)
> -		return -1;
> +	/* Test UART existance. */
> +	if (kgdb8250_ioread(UART_LSR) == 0xff)
> +		return -EIO;
>  
> -	/* disable interrupts */
> -	kgdb_iowrite(0, UART_IER);
> +	/* Disable interrupts. */
> +	kgdb8250_iowrite(0, UART_IER);
>  
> -#if defined(CONFIG_ARCH_OMAP1510)
> +#ifdef CONFIG_ARCH_OMAP1510
>  	/* Workaround to enable 115200 baud on OMAP1510 internal ports */
>  	if (cpu_is_omap1510() && is_omap_port((void *)kgdb8250_addr)) {
>  		if (kgdb8250_baud == 115200) {
>  			base_baud = 1;
>  			kgdb8250_baud = 1;
> -			kgdb_iowrite(1, UART_OMAP_OSC_12M_SEL);
> +			kgdb8250_iowrite(1, UART_OMAP_OSC_12M_SEL);
>  		} else
> -			kgdb_iowrite(0, UART_OMAP_OSC_12M_SEL);
> +			kgdb8250_iowrite(0, UART_OMAP_OSC_12M_SEL);
>  	}
>  #endif
> -	/* set DLAB */
> -	kgdb_iowrite(UART_LCR_DLAB, UART_LCR);
>  
> -	/* set baud */
> -	kgdb_iowrite((base_baud / kgdb8250_baud) & 0xff, UART_DLL);
> -	kgdb_iowrite((base_baud / kgdb8250_baud) >> 8, UART_DLM);
> -
> -	/* reset DLAB, set LCR */
> -	kgdb_iowrite(UART_LCR_WLEN8, UART_LCR);
> -
> -	/* set DTR and RTS */
> -	kgdb_iowrite(UART_MCR_OUT2 | UART_MCR_DTR | UART_MCR_RTS, UART_MCR);
> -
> -	/* setup fifo */
> -	kgdb_iowrite(UART_FCR_ENABLE_FIFO | UART_FCR_CLEAR_RCVR
> -		| UART_FCR_CLEAR_XMIT | UART_FCR_TRIGGER_8,
> -		UART_FCR);
> -
> -	/* clear pending interrupts */
> -	kgdb_ioread(UART_IIR);
> -	kgdb_ioread(UART_RX);
> -	kgdb_ioread(UART_LSR);
> -	kgdb_ioread(UART_MSR);
> -
> -	/* turn on RX interrupt only */
> -	kgdb_iowrite(UART_IER_RDI, UART_IER);
> +	/* Line settings 8n1, no FIFO, DTR+RTS on. */
> +	kgdb8250_iowrite(UART_LCR_WLEN8, UART_LCR);
> +	kgdb8250_iowrite(0, UART_FCR);
> +	kgdb8250_iowrite(UART_MCR_OUT2 | UART_MCR_DTR |
> +			 UART_MCR_RTS, UART_MCR);
> +
> +	/* Set baud rate. */
> +	kgdb8250_iowrite(UART_LCR_WLEN8 | UART_LCR_DLAB, UART_LCR);
> +	kgdb8250_iowrite((base_baud / kgdb8250_baud) & 0xff, UART_DLL);
> +	kgdb8250_iowrite((base_baud / kgdb8250_baud) >> 8, UART_DLM);
> +	kgdb8250_iowrite(UART_LCR_WLEN8, UART_LCR);
> +
> +	/* Clear pending interrupts. */
> +	(void) kgdb8250_ioread(UART_IIR);
> +	(void) kgdb8250_ioread(UART_RX);
> +	(void) kgdb8250_ioread(UART_LSR);
> +	(void) kgdb8250_ioread(UART_MSR);
>  
>  	/*
>  	 * Borrowed from the main 8250 driver.
> @@ -238,344 +189,308 @@ static int kgdb8250_uart_init(void)
>  	 * trying to write and read a 1 just to make sure it's not
>  	 * already a 1 and maybe locked there before we even start start.
>  	 */
> -	ier = kgdb_ioread(UART_IER);
> -	kgdb_iowrite(ier & ~UART_IER_UUE, UART_IER);
> -	if (!(kgdb_ioread(UART_IER) & UART_IER_UUE)) {
> +	ier = kgdb8250_ioread(UART_IER);
> +	kgdb8250_iowrite(ier & ~UART_IER_UUE, UART_IER);
> +	if (!(kgdb8250_ioread(UART_IER) & UART_IER_UUE)) {
>  		/*
>  		 * OK it's in a known zero state, try writing and reading
>  		 * without disturbing the current state of the other bits.
>  		 */
> -		kgdb_iowrite(ier | UART_IER_UUE, UART_IER);
> -		if (kgdb_ioread(UART_IER) & UART_IER_UUE)
> -			/*
> -			 * It's an Xscale.
> -			 */
> +		kgdb8250_iowrite(ier | UART_IER_UUE, UART_IER);
> +		if (kgdb8250_ioread(UART_IER) & UART_IER_UUE)
> +			/* It's an Xscale. */
>  			ier |= UART_IER_UUE | UART_IER_RTOIE;
>  	}
> -	kgdb_iowrite(ier, UART_IER);
> +	kgdb8250_iowrite(ier, UART_IER);
> +
>  	return 0;
>  }
>  
>  /*
> - * Copy the old serial_state table to our uart_port table if we haven't
> - * had values specifically configured in.  We need to make sure this only
> - * happens once.
> + * Syntax for this cmdline option is:
> + *   <io|mmio|mmap>,<address>[/<regshift>],<baud rate>,<irq> or
> + *   ttyS<n>,<baud rate>
>   */
> -static void __init kgdb8250_copy_rs_table(void)
> +static int kgdb8250_parse_config(char *str)
>  {
> -#ifdef CONFIG_KGDB_SIMPLE_SERIAL
> -	int i;
> +	int line, err;
>  
> -	if (!should_copy_rs_table)
> -		return;
> +	/* Save the option string in case we fail and can retry later. */
> +	strncpy(config, str, KGD8250_MAX_CONFIG_STR-1);
>  
> -	for (i = 0; i < ARRAY_SIZE(old_rs_table) && i < UART_NR; i++) {
> -		if (kgdb8250_ports[i].iobase || kgdb8250_ports[i].irq ||
> -			kgdb8250_ports[i].membase)
> -			continue;
> -		kgdb8250_ports[i].iobase = old_rs_table[i].port;
> -		kgdb8250_ports[i].irq = irq_canonicalize(old_rs_table[i].irq);
> -		kgdb8250_ports[i].uartclk = old_rs_table[i].baud_base * 16;
> -		kgdb8250_ports[i].membase = old_rs_table[i].iomem_base;
> -		kgdb8250_ports[i].iotype = old_rs_table[i].io_type;
> -		kgdb8250_ports[i].regshift = old_rs_table[i].iomem_reg_shift;
> -		kgdb8250_ports[i].line = i;
> -	}
> +	/* Empty config or leading white space (like LF) means "disabled" */
> +	if (!strlen(config) || isspace(config[0]))
> +		return 0;
>  
> -	should_copy_rs_table = 0;
> -#endif
> -}
> +	if (!strncmp(str, "io", 2)) {
> +		kgdb8250_port.iotype = UPIO_PORT;
> +		str += 2;
> +	} else if (!strncmp(str, "mmap", 4)) {
> +		kgdb8250_port.iotype = UPIO_MEM;
> +		kgdb8250_port.flags |= UPF_IOREMAP;
> +		str += 4;
> +	} else if (!strncmp(str, "mmio", 4)) {
> +		kgdb8250_port.iotype = UPIO_MEM;
> +		kgdb8250_port.flags &= ~UPF_IOREMAP;
> +		str += 4;
> +	} else if (!strncmp(str, "ttyS", 4)) {
> +		str += 4;
> +		if (*str < '0' || *str > '9')
> +			return -EINVAL;
> +		line = simple_strtoul(str, &str, 10);
> +		if (line >= CONFIG_SERIAL_8250_NR_UARTS)
> +			return -EINVAL;
>  
> -/*
> - * Hookup our IRQ line now that it is safe to do so, after we grab any
> - * memory regions we might need to.  If we haven't been initialized yet,
> - * go ahead and copy the old_rs_table in.
> - */
> -static void __init kgdb8250_late_init(void)
> -{
> -	/* Setup the KGDB uart table if not already initialized */
> -	kgdb8250_copy_rs_table();
> +		err = serial8250_get_port_def(&kgdb8250_port, line);
> +		if (err) {
> +			if (late_init_passed)
> +				return err;
> +			printk(KERN_WARNING "kgdb8250: ttyS%d init delayed, "
> +			       "use io|mmio|mmap syntax for early init.\n",
> +			       line);
> +			return 0;
> +		}
>  
> -#if defined(CONFIG_SERIAL_8250) || defined(CONFIG_SERIAL_8250_MODULE)
> -	/* Take the port away from the main driver. */
> -	serial8250_unregister_by_port(current_port);
> +		if (*str != ',')
> +			return -EINVAL;
> +		str++;
>  
> -	/* Now reinit the port as the above has disabled things. */
> -	kgdb8250_uart_init();
> -#endif
> -	/* We may need to call request_mem_region() first. */
> -	if (kgdb8250_needs_request_mem_region)
> -		request_mem_region(current_port->mapbase,
> -				   8 << current_port->regshift, "kgdb");
> -	if (request_irq(current_port->irq, kgdb8250_interrupt, IRQF_SHARED,
> -			"GDB-stub", current_port) < 0)
> -		printk(KERN_ERR "KGDB failed to request the serial IRQ (%d)\n",
> -		       current_port->irq);
> -}
> -
> -static __init int kgdb_init_io(void)
> -{
> -	/* Setup the KGDB uart table if not already initialized */
> -	kgdb8250_copy_rs_table();
> -
> -	/* We're either a module and parse a config string, or we have a
> -	 * semi-static config. */
> -#ifdef CONFIG_KGDB_8250_MODULE
> -	if (strlen(config)) {
> -		if (kgdb8250_opt(config))
> +		kgdb8250_baud = simple_strtoul(str, &str, 10);
> +		if (!kgdb8250_baud)
>  			return -EINVAL;
> -	} else {
> -		printk(KERN_ERR "kgdb8250: argument error, usage: "
> -		       "kgdb8250=<io or mmio>,<address>,<baud rate>,<irq>\n");
> -		printk(KERN_ERR "kgdb8250: alt usage: "
> -		       "kgdb8250=<line #>,<baud rate>\n");
> +
> +		if (*str == ',')
> +			return -EINVAL;
> +
> +		goto finish;
> +	} else
> +		return -EINVAL;
> +
> +	if (*str != ',')
>  		return -EINVAL;
> +	str++;
> +
> +	if (kgdb8250_port.iotype == UPIO_PORT)
> +		kgdb8250_port.iobase = simple_strtoul(str, &str, 16);
> +	else {
> +		if (kgdb8250_port.flags & UPF_IOREMAP)
> +			kgdb8250_port.mapbase =
> +				(unsigned long) simple_strtoul(str, &str, 16);
> +		else
> +			kgdb8250_port.membase =
> +				(void *) simple_strtoul(str, &str, 16);
> +	}
> +
> +	if (*str == '/') {
> +		str++;
> +		kgdb8250_port.regshift = simple_strtoul(str, &str, 10);
>  	}
> -#elif defined(CONFIG_KGDB_SIMPLE_SERIAL)
> -	if (kgdb8250_line < 0)
> +
> +	if (*str != ',')
>  		return -EINVAL;
> -	/* Setup our pointer to the serial port now. */
> -	current_port = &kgdb8250_ports[kgdb8250_line];
> -	if (!current_port->membase && !current_port->iobase &&
> -		!current_port->irq)
> -		serial8250_get_port_def(current_port, kgdb8250_line);
> -#elif defined(CONFIG_KGDB_8250_CONF_STRING)
> -	if (kgdb8250_opt(CONFIG_KGDB_8250_CONF_STRING))
> +	str++;
> +
> +	kgdb8250_baud = simple_strtoul(str, &str, 10);
> +	if (!kgdb8250_baud)
>  		return -EINVAL;
> -#else
> +
> +	if (*str != ',')
>  		return -EINVAL;
> -#endif
> +	str++;
> +
> +	kgdb8250_port.irq = simple_strtoul(str, &str, 10);
> +
> +finish:
> +	err = kgdb_register_io_module(&kgdb8250_io_ops);
> +	if (err)
> +		kgdb8250_addr = 0;
>  
> +	return err;
> +}
>  
> +static int kgdb8250_early_init(void)
> +{
>  	/* Internal driver setup. */
> -	switch (current_port->iotype) {
> +	switch (kgdb8250_port.iotype) {
>  	case UPIO_MEM:
> -		if (current_port->mapbase)
> -			kgdb8250_needs_request_mem_region = 1;
> -		if (current_port->flags & UPF_IOREMAP) {
> -			current_port->membase = ioremap(current_port->mapbase,
> -						8 << current_port->regshift);
> -			if (!current_port->membase)
> -				return -EIO;	/* Failed. */
> -		}
> -		kgdb8250_addr = current_port->membase;
> +		if (kgdb8250_port.flags & UPF_IOREMAP)
> +			kgdb8250_port.membase = ioremap(kgdb8250_port.mapbase,
> +						8 << kgdb8250_port.regshift);
> +		kgdb8250_addr = kgdb8250_port.membase;
>  		break;
>  	case UPIO_PORT:
>  	default:
> -		kgdb8250_addr = ioport_map(current_port->iobase,
> -					   8 << current_port->regshift);
> -		if (!kgdb8250_addr)
> -			return -EIO;	/* Failed. */
> +		kgdb8250_addr = ioport_map(kgdb8250_port.iobase,
> +					   8 << kgdb8250_port.regshift);
>  	}
> +	if (!kgdb8250_addr)
> +		return -EIO;
>  
> -	if (kgdb8250_uart_init() == -1) {
> -		printk(KERN_ERR "kgdb8250: init failed\n");
> +	if (kgdb8250_uart_init() < 0) {
> +		printk(KERN_ERR "kgdb8250: UART initialization failed\n");
>  		return -EIO;
>  	}
> -#ifdef CONFIG_KGDB_8250_MODULE
> -	/* Attach the kgdb irq. When this is built into the kernel, it
> -	 * is called as a part of late_init sequence.
> -	 */
> -	kgdb8250_late_init();
> -	if (kgdb_register_io_module(&local_kgdb_io_ops))
> -		return -EINVAL;
> -
> -	printk(KERN_INFO "kgdb8250: debugging enabled\n");
> -#endif				/* CONFIG_KGD_8250_MODULE */
>  
>  	return 0;
>  }
>  
> -#ifdef CONFIG_KGDB_8250_MODULE
> -/* If it is a module the kgdb_io_ops should be a static which
> - * is passed to the KGDB I/O initialization
> - */
> -static void kgdb8250_pre_exception_handler(void);
> -static void kgdb8250_post_exception_handler(void);
> +static int kgdb8250_late_init(void)
> +{
> +	int err;
>  
> -static struct kgdb_io local_kgdb_io_ops = {
> -#else				/* ! CONFIG_KGDB_8250_MODULE */
> -struct kgdb_io kgdb_io_ops = {
> -#endif				/* ! CONFIG_KGD_8250_MODULE */
> -	.read_char = kgdb_get_debug_char,
> -	.write_char = kgdb_put_debug_char,
> -	.init = kgdb_init_io,
> -	.late_init = kgdb8250_late_init,
> -#ifdef CONFIG_KGDB_8250_MODULE
> -	.pre_exception = kgdb8250_pre_exception_handler,
> -	.post_exception = kgdb8250_post_exception_handler,
> -#endif
> -};
> +	if (fully_initialized)
> +		return 0;
>  
> -/**
> - * 	kgdb8250_add_port - Define a serial port for use with KGDB
> - * 	@i: The index of the port being added
> - * 	@serial_req: The &struct uart_port describing the port
> - *
> - * 	On platforms where we must register the serial device
> - * 	dynamically, this is the best option if a platform also normally
> - * 	calls early_serial_setup().
> - */
> -void kgdb8250_add_port(int i, struct uart_port *serial_req)
> -{
> -	if (i >= UART_NR) {
> -		printk(KERN_ERR "KGDB dynamic uart registration failed"
> -		   "NR_UARTS is too small");
> -		return;
> +	late_init_passed = 1;
> +
> +	/*
> +	 * If we didn't initialize yet or if an earlier attempt failed,
> +	 * evaluate the configuration and register with KGDB.
> +	 */
> +	if (!kgdb8250_addr) {
> +		err = kgdb8250_parse_config(config);
> +		if (err || !kgdb8250_addr)
> +			return err;
>  	}
>  
> -	/* Copy the whole thing over. */
> -	if (current_port != &kgdb8250_ports[i])
> -		memcpy(&kgdb8250_ports[i], serial_req,
> -		sizeof(struct uart_port));
> -}
> +	/* Take the port away from the main driver. */
> +	hijacked_line = serial8250_find_port(&kgdb8250_port);
> +	if (hijacked_line >= 0)
> +		serial8250_unregister_port(hijacked_line);
>  
> -/**
> - * 	kgdb8250_add_platform_port - Define a serial port for use with KGDB
> - * 	@i: The index of the port being added
> - * 	@p: The &struct plat_serial8250_port describing the port
> - *
> - * 	On platforms where we must register the serial device
> - * 	dynamically, this is the best option if a platform normally
> - * 	handles uart setup with an array of &struct plat_serial8250_port.
> - */
> -void __init kgdb8250_add_platform_port(int i, struct plat_serial8250_port *p)
> -{
> -	/* Make sure we've got the built-in data before we override. */
> -	kgdb8250_copy_rs_table();
> +	/* Now reinit the port as the above has disabled things. */
> +	kgdb8250_uart_init();
>  
> -	if (i >= UART_NR) {
> -		printk(KERN_ERR "KGDB dynamic uart registration failed"
> -		   "NR_UARTS is too small");
> -		return;
> +	/* Request memory/io regions that we use. */
> +	if (kgdb8250_port.flags & UPF_IOREMAP) {
> +		if (!request_mem_region(kgdb8250_port.mapbase,
> +					8 << kgdb8250_port.regshift, "kgdb"))
> +			goto rollback;
> +	} else if (kgdb8250_port.iotype == UPIO_PORT) {
> +		if (!request_region(kgdb8250_port.iobase,
> +				    8 << kgdb8250_port.regshift, "kgdb"))
> +			goto rollback;
> +	}
> +
> +	if (request_irq(kgdb8250_port.irq, kgdb8250_interrupt, IRQF_SHARED,
> +			"kgdb", &kgdb8250_port) == 0) {
> +		/* Turn on RX interrupt only. */
> +		kgdb8250_iowrite(UART_IER_RDI, UART_IER);
> +
> +		kgdb8250_irq = kgdb8250_port.irq;
> +	} else {
> +		/*
> +		 * The IRQ line is not mandatory for KGDB to provide at least
> +		 * basic services. So report the error and continue.
> +		 */
> +		printk(KERN_ERR "kgdb8250: failed to request the IRQ (%d)\n",
> +		       kgdb8250_irq);
> +		kgdb8250_irq = -1;
>  	}
>  
> -	kgdb8250_ports[i].iobase = p->iobase;
> -	kgdb8250_ports[i].membase = p->membase;
> -	kgdb8250_ports[i].irq = p->irq;
> -	kgdb8250_ports[i].uartclk = p->uartclk;
> -	kgdb8250_ports[i].regshift = p->regshift;
> -	kgdb8250_ports[i].iotype = p->iotype;
> -	kgdb8250_ports[i].flags = p->flags;
> -	kgdb8250_ports[i].mapbase = p->mapbase;
> +	fully_initialized = 1;
> +	return 0;
> +
> +rollback:
> +	if (hijacked_line >= 0)
> +		serial8250_register_port(&kgdb8250_port);
> +
> +	printk(KERN_CRIT "kgdb: Unable to reserve mandatory hardware "
> +			 "resources.\n");
> +	return -EBUSY;
>  }
>  
> -/*
> - * Syntax for this cmdline option is:
> - * kgdb8250=<io or mmio>,<address>,<baud rate>,<irq>"
> - */
> -static int __init kgdb8250_opt(char *str)
> +static void kgdb8250_cleanup(void)
>  {
> -	/* We'll fill out and use the first slot. */
> -	current_port = &kgdb8250_ports[0];
> +	void *ioaddr = kgdb8250_addr;
>  
> -	if (!strncmp(str, "io", 2)) {
> -		current_port->iotype = UPIO_PORT;
> -		str += 2;
> -	} else if (!strncmp(str, "mmap", 4)) {
> -		current_port->iotype = UPIO_MEM;
> -		current_port->flags |= UPF_IOREMAP;
> -		str += 4;
> -	} else if (!strncmp(str, "mmio", 4)) {
> -		current_port->iotype = UPIO_MEM;
> -		current_port->flags &= ~UPF_IOREMAP;
> -		str += 4;
> -	} else if (*str >= '0' || *str <= '9') {
> -		kgdb8250_line = *str - '0';
> -		/* UARTS in the list from 0 -> 9 */
> -		if (kgdb8250_line >= UART_NR)
> -			goto errout;
> -		current_port = &kgdb8250_ports[kgdb8250_line];
> -		if (serial8250_get_port_def(current_port, kgdb8250_line))
> -			goto errout;
> -		str++;
> -		if (*str != ',')
> -			goto errout;
> -		str++;
> -		kgdb8250_baud = simple_strtoul(str, &str, 10);
> -		if (!kgdb8250_baud)
> -			goto errout;
> -		if (*str == ',')
> -			goto errout;
> -		goto finish;
> -	} else
> -		goto errout;
> +	if (!kgdb8250_addr)
> +		return;
>  
> -	if (*str != ',')
> -		goto errout;
> -	str++;
> +	/* Disable and unregister interrupt. */
> +	kgdb8250_iowrite(0, UART_IER);
> +	(void) kgdb8250_ioread(UART_RX);
> +
> +	if (kgdb8250_irq >= 0)
> +		free_irq(kgdb8250_irq, &kgdb8250_port);
> +
> +	/* Deregister from KGDB core. */
> +	kgdb_unregister_io_module(&kgdb8250_io_ops);
> +	kgdb8250_addr = 0;
>  
> -	if (current_port->iotype == UPIO_PORT)
> -		current_port->iobase = simple_strtoul(str, &str, 16);
> -	else {
> -		if (current_port->flags & UPF_IOREMAP)
> -			current_port->mapbase =
> -				(unsigned long) simple_strtoul(str, &str, 16);
> -		else
> -			current_port->membase =
> -				(void *) simple_strtoul(str, &str, 16);
> +	if (!fully_initialized)
> +		return;
> +
> +	fully_initialized = 0;
> +
> +	if (kgdb8250_port.iotype == UPIO_PORT) {
> +		ioport_unmap(ioaddr);
> +		release_region(kgdb8250_port.iobase,
> +			       8 << kgdb8250_port.regshift);
> +	} else if (kgdb8250_port.flags & UPF_IOREMAP) {
> +		iounmap(kgdb8250_port.membase);
> +		release_mem_region(kgdb8250_port.mapbase,
> +				   8 << kgdb8250_port.regshift);
>  	}
>  
> -	if (*str != ',')
> -		goto errout;
> -	str++;
> +	/* Give the port back to the 8250 driver. */
> +	if (hijacked_line >= 0)
> +		serial8250_register_port(&kgdb8250_port);
> +}
>  
> -	kgdb8250_baud = simple_strtoul(str, &str, 10);
> -	if (!kgdb8250_baud)
> -		goto errout;
> +static int kgdb8250_set_config(const char *kmessage, struct kernel_param *kp)
> +{
> +	int err;
>  
> -	if (*str != ',')
> -		goto errout;
> -	str++;
> +	if (strlen(kmessage) >= KGD8250_MAX_CONFIG_STR) {
> +		printk(KERN_ERR "%s: config string too long.\n", kp->name);
> +		return -ENOSPC;
> +	}
>  
> -	current_port->irq = simple_strtoul(str, &str, 10);
> +	if (kgdb_connected) {
> +		printk(KERN_ERR "kgd8250: Cannot reconfigure while KGDB is "
> +				"connected.\n");
> +		return -EBUSY;
> +	}
>  
> -finish:
> -#ifdef CONFIG_KGDB_SIMPLE_SERIAL
> -	should_copy_rs_table = 0;
> -#endif
> +	if (kgdb8250_addr)
> +		kgdb8250_cleanup();
>  
> -	return 0;
> +	err = kgdb8250_parse_config((char *)kmessage);
> +
> +	if (err || !late_init_passed)
> +		return err;
>  
> -errout:
> -	printk(KERN_ERR "Invalid syntax for option kgdb8250=\n");
> -	return 1;
> +	/* Call the botton-half initialization as we are re-configuring. */
> +	return kgdb8250_late_init();
>  }
>  
> -#ifdef CONFIG_KGDB_8250_MODULE
>  static void kgdb8250_pre_exception_handler(void)
>  {
> -	if (!module_refcount(THIS_MODULE))
> +	if (!kgdb_connected)
>  		try_module_get(THIS_MODULE);
>  }
>  
>  static void kgdb8250_post_exception_handler(void)
>  {
> -	if (!kgdb_connected && module_refcount(THIS_MODULE))
> +	if (!kgdb_connected)
>  		module_put(THIS_MODULE);
>  }
>  
> -static void cleanup_kgdb8250(void)
> -{
> -	kgdb_unregister_io_module(&local_kgdb_io_ops);
> +static struct kgdb_io kgdb8250_io_ops = {
> +	.name = "kgdb8250",
> +	.read_char = kgdb8250_get_debug_char,
> +	.write_char = kgdb8250_put_debug_char,
> +	.init = kgdb8250_early_init,	.pre_exception = kgdb8250_pre_exception_handler,
> +	.post_exception = kgdb8250_post_exception_handler,
> +};
>  
> -	/* Clean up the irq and memory */
> -	free_irq(current_port->irq, current_port);
> +module_init(kgdb8250_late_init);
> +module_exit(kgdb8250_cleanup);
>  
> -	if (kgdb8250_needs_request_mem_region)
> -		release_mem_region(current_port->mapbase,
> -				   8 << current_port->regshift);
> -	/* Hook up the serial port back to what it was previously
> -	 * hooked up to.
> -	 */
> -#if defined(CONFIG_SERIAL_8250) || defined(CONFIG_SERIAL_8250_MODULE)
> -	/* Give the port back to the 8250 driver. */
> -	serial8250_register_port(current_port);
> -#endif
> -}
> +module_param_call(kgdb8250, kgdb8250_set_config, param_get_string, &kps, 0644);
> +MODULE_PARM_DESC(kgdb8250, "ttyS<n>,<baud rate>");
>  
> -module_init(kgdb_init_io);
> -module_exit(cleanup_kgdb8250);
> -#else				/* ! CONFIG_KGDB_8250_MODULE */
> -early_param("kgdb8250", kgdb8250_opt);
> -#endif				/* ! CONFIG_KGDB_8250_MODULE */
> +#ifdef CONFIG_KGDB_8250
> +early_param("kgdb8250", kgdb8250_parse_config);
> +#endif
> Index: b/drivers/serial/8250.c
> ===================================================================
> --- a/drivers/serial/8250.c
> +++ b/drivers/serial/8250.c
> @@ -2639,6 +2639,7 @@ int serial8250_find_port(struct uart_por
>  	}
>  	return -ENODEV;
>  }
> +EXPORT_SYMBOL_GPL(serial8250_find_port);
>  
>  #define SERIAL8250_CONSOLE	&serial8250_console
>  #else
> @@ -2926,51 +2927,28 @@ EXPORT_SYMBOL(serial8250_unregister_port
>   *  @line: specific serial line index
>   *
>   *  Return 0 if the port existed
> - *  Return 1 on failure
> + *  Return -errno on failure
>   */
> -
>  int serial8250_get_port_def(struct uart_port *port, int line)
>  {
> -	struct uart_8250_port *uart;
> +	struct uart_port *port8250 = &serial8250_ports[line].port;
>  
> -	if (line < 0 || line >= UART_NR)
> -		return 1;
> -	uart = &serial8250_ports[line];
> -	if (uart) {
> -		port->iobase = uart->port.iobase;
> -		port->membase = uart->port.membase;
> -		port->irq = uart->port.irq;
> -		port->uartclk = uart->port.uartclk;
> -		port->fifosize = uart->port.fifosize;
> -		port->regshift = uart->port.regshift;
> -		port->iotype = uart->port.iotype;
> -		port->flags = uart->port.flags;
> -		port->mapbase = uart->port.mapbase;
> -		port->dev =	uart->port.dev;
> -		return 0;
> -	}
> -	return 1;
> -}
> -EXPORT_SYMBOL(serial8250_get_port_def);
> -
> -/**
> - *	serial8250_unregister_by_port - remove a 16x50 serial port
> - *	at runtime.
> - *	@port: A &struct uart_port that describes the port to remove.
> - *
> - *	Remove one serial port.  This may not be called from interrupt
> - *	context.  We hand the port back to the our control.
> - */
> -void serial8250_unregister_by_port(struct uart_port *port)
> -{
> -	struct uart_8250_port *uart;
> -
> -	uart = serial8250_find_match_or_unused(port);
> +	if (!port8250->iobase && !port8250->membase)
> +		return -ENODEV;
>  
> -	if (uart)
> -		serial8250_unregister_port(uart->port.line);
> +	port->iobase   = port8250->iobase;
> +	port->membase  = port8250->membase;
> +	port->irq      = port8250->irq;
> +	port->uartclk  = port8250->uartclk;
> +	port->fifosize = port8250->fifosize;
> +	port->regshift = port8250->regshift;
> +	port->iotype   = port8250->iotype;
> +	port->flags    = port8250->flags;
> +	port->mapbase  = port8250->mapbase;
> +	port->dev      = port8250->dev;
> +	return 0;
>  }
> -EXPORT_SYMBOL(serial8250_unregister_by_port);
> +EXPORT_SYMBOL_GPL(serial8250_get_port_def);
>  
>  static int __init serial8250_init(void)
>  {
> Index: b/drivers/serial/Kconfig
> ===================================================================
> --- a/drivers/serial/Kconfig
> +++ b/drivers/serial/Kconfig
> @@ -942,6 +942,9 @@ config SERIAL_CORE
>  config SERIAL_CORE_CONSOLE
>  	bool
>  
> +config SERIAL_POLL
> +	bool
> +
>  config SERIAL_68328
>  	bool "68328 serial support"
>  	depends on M68328 || M68EZ328 || M68VZ328
> Index: b/drivers/serial/serial_core.c
> ===================================================================
> --- a/drivers/serial/serial_core.c
> +++ b/drivers/serial/serial_core.c
> @@ -2439,12 +2439,6 @@ int uart_add_one_port(struct uart_driver
>  	 */
>  	port->flags &= ~UPF_DEAD;
>  
> -#if defined(CONFIG_KGDB_8250)
> -	/* Add any 8250-like ports we find later. */
> -	if (port->type <= PORT_MAX_8250)
> -		kgdb8250_add_port(port->line, port);
> -#endif
> -
>   out:
>  	mutex_unlock(&state->mutex);
>  	mutex_unlock(&port_mutex);
> Index: b/include/linux/kgdb.h
> ===================================================================
> --- a/include/linux/kgdb.h
> +++ b/include/linux/kgdb.h
> @@ -233,6 +233,7 @@ struct kgdb_arch {
>  
>  /**
>   * struct kgdb_io - Describe the interface for an I/O driver to talk with KGDB.
> + * @name: Name of the I/O driver.
>   * @read_char: Pointer to a function that will return one char.
>   * @write_char: Pointer to a function that will write one char.
>   * @flush: Pointer to a function that will flush any pending writes.
> @@ -255,25 +256,20 @@ struct kgdb_arch {
>   * notified.
>   */
>  struct kgdb_io {
> -	int	(*read_char) (void);
> -	void	(*write_char) (u8);
> -	void	(*flush) (void);
> -	int	(*init) (void);
> -	void	(*late_init) (void);
> -	void	(*pre_exception) (void);
> -	void	(*post_exception) (void);
> +	const char	*name;
> +	int		(*read_char) (void);
> +	void		(*write_char) (u8);
> +	void		(*flush) (void);
> +	int		(*init) (void);
> +	void		(*pre_exception) (void);
> +	void		(*post_exception) (void);
>  };
>  
> -extern struct kgdb_io		kgdb_io_ops;
>  extern struct kgdb_arch		arch_kgdb_ops;
>  
>  int kgdb_register_io_module(struct kgdb_io *local_kgdb_io_ops);
>  void kgdb_unregister_io_module(struct kgdb_io *local_kgdb_io_ops);
>  
> -void kgdb8250_add_port(int i, struct uart_port *serial_req);
> -void __init
> -kgdb8250_add_platform_port(int i, struct plat_serial8250_port *serial_req);
> -
>  int kgdb_hex2long(char **ptr, long *long_val);
>  char *kgdb_mem2hex(char *mem, char *buf, int count);
>  char *kgdb_hex2mem(char *buf, char *mem, int count);
> Index: b/kernel/kgdb.c
> ===================================================================
> --- a/kernel/kgdb.c
> +++ b/kernel/kgdb.c
> @@ -53,8 +53,7 @@
>  #include <asm/atomic.h>
>  #include <asm/system.h>
>  
> -static int __initdata kgdb_internal_init_complete;
> -static int __initdata kgdb_break_asap;
> +static int kgdb_break_asap;
>  
>  struct kgdb_state {
>  	int			all_cpus_synced;
> @@ -89,30 +88,16 @@ int				kgdb_io_module_registered;
>  /* Guard for recursive entry */
>  static int			exception_level;
>  
> -#ifdef CONFIG_KGDB_ATTACH_WAIT
> -static int			attachwait = 1;
> -#else
> -static int			attachwait;
> -#endif
> -
> -module_param(attachwait, int, 0644);
> -MODULE_PARM_DESC(attachwait, "Wait for remote debugger after an exception");
> -
> -/* We provide a kgdb_io_ops structure that may be overriden. */
> -struct kgdb_io __weak		kgdb_io_ops;
> -EXPORT_SYMBOL_GPL(kgdb_io_ops);
> -
> -static struct kgdb_io		kgdb_io_ops_prev[KGDB_MAX_IO_HANDLERS];
> -
> -static int			kgdb_io_handler_cnt;
> +static struct kgdb_io		*kgdb_io_ops;
> +static DEFINE_SPINLOCK(kgdb_registration_lock);
>  
>  /*
>   * Holds information about breakpoints in a kernel. These breakpoints are
>   * added and removed by gdb.
>   */
> -struct kgdb_bkpt		kgdb_break[KGDB_MAX_BREAKPOINTS];
> -
> -struct kgdb_arch		*kgdb_ops = &arch_kgdb_ops;
> +struct kgdb_bkpt		kgdb_break[KGDB_MAX_BREAKPOINTS] = {
> +	[0 ... KGDB_MAX_BREAKPOINTS-1] = { .state = BP_UNDEFINED }
> +};
>  
>  /*
>   * KGDB locking is really nasty at places - but we really can only
> @@ -126,7 +111,9 @@ struct kgdb_arch		*kgdb_ops = &arch_kgdb
>  #define ROUNDUP_WAIT		640000	/* Arbitrary, increase if needed. */
>  #define BUF_THREAD_ID_SIZE	16
>  
> -static spinlock_t		slave_cpu_locks[NR_CPUS];
> +static spinlock_t		slave_cpu_locks[NR_CPUS] = {
> +	[0 ... NR_CPUS-1] = __SPIN_LOCK_UNLOCKED(slave_cpu_locks)
> +};
>  static atomic_t			cpu_in_debugger[NR_CPUS];
>  atomic_t			kgdb_setting_breakpoint;
>  
> @@ -185,7 +172,7 @@ int __weak kgdb_arch_set_breakpoint(unsi
>  	if (kgdb_get_mem((char *)addr, saved_instr, BREAK_INSTR_SIZE) != 0)
>  		return -1;
>  
> -	if (kgdb_set_mem((char *)addr, kgdb_ops->gdb_bpt_instr,
> +	if (kgdb_set_mem((char *)addr, arch_kgdb_ops.gdb_bpt_instr,
>  						BREAK_INSTR_SIZE) != 0)
>  		return -1;
>  	return 0;
> @@ -228,14 +215,12 @@ static void get_packet(char *buffer)
>  	int count;
>  	char ch;
>  
> -	if (!kgdb_io_ops.read_char)
> -		return;
>  	do {
>  		/*
>  		 * Spin and wait around for the start character, ignore all
>  		 * other characters:
>  		 */
> -		while ((ch = (kgdb_io_ops.read_char())) != '$')
> +		while ((ch = (kgdb_io_ops->read_char())) != '$')
>  			/* nothing */;
>  
>  		kgdb_connected = 1;
> @@ -248,7 +233,7 @@ static void get_packet(char *buffer)
>  		 * now, read until a # or end of buffer is found:
>  		 */
>  		while (count < (BUFMAX - 1)) {
> -			ch = kgdb_io_ops.read_char();
> +			ch = kgdb_io_ops->read_char();
>  			if (ch == '#')
>  				break;
>  			checksum = checksum + ch;
> @@ -258,17 +243,17 @@ static void get_packet(char *buffer)
>  		buffer[count] = 0;
>  
>  		if (ch == '#') {
> -			xmitcsum = hex(kgdb_io_ops.read_char()) << 4;
> -			xmitcsum += hex(kgdb_io_ops.read_char());
> +			xmitcsum = hex(kgdb_io_ops->read_char()) << 4;
> +			xmitcsum += hex(kgdb_io_ops->read_char());
>  
>  			if (checksum != xmitcsum)
>  				/* failed checksum */
> -				kgdb_io_ops.write_char('-');
> +				kgdb_io_ops->write_char('-');
>  			else
>  				/* successful transfer */
> -				kgdb_io_ops.write_char('+');
> -			if (kgdb_io_ops.flush)
> -				kgdb_io_ops.flush();
> +				kgdb_io_ops->write_char('+');
> +			if (kgdb_io_ops->flush)
> +				kgdb_io_ops->flush();
>  		}
>  	} while (checksum != xmitcsum);
>  }
> @@ -283,34 +268,31 @@ static void put_packet(char *buffer)
>  	int count;
>  	char ch;
>  
> -	if (!kgdb_io_ops.write_char)
> -		return;
> -
>  	/*
>  	 * $<packet info>#<checksum>.
>  	 */
>  	while (1) {
> -		kgdb_io_ops.write_char('$');
> +		kgdb_io_ops->write_char('$');
>  		checksum = 0;
>  		count = 0;
>  
>  		while ((ch = buffer[count])) {
> -			kgdb_io_ops.write_char(ch);
> +			kgdb_io_ops->write_char(ch);
>  			checksum += ch;
>  			count++;
>  		}
>  
> -		kgdb_io_ops.write_char('#');
> -		kgdb_io_ops.write_char(hexchars[checksum >> 4]);
> -		kgdb_io_ops.write_char(hexchars[checksum % 16]);
> -		if (kgdb_io_ops.flush)
> -			kgdb_io_ops.flush();
> +		kgdb_io_ops->write_char('#');
> +		kgdb_io_ops->write_char(hexchars[checksum >> 4]);
> +		kgdb_io_ops->write_char(hexchars[checksum % 16]);
> +		if (kgdb_io_ops->flush)
> +			kgdb_io_ops->flush();
>  
>  		/* Now see what we get in reply. */
> -		ch = kgdb_io_ops.read_char();
> +		ch = kgdb_io_ops->read_char();
>  
>  		if (ch == 3)
> -			ch = kgdb_io_ops.read_char();
> +			ch = kgdb_io_ops->read_char();
>  
>  		/* If we get an ACK, we are done. */
>  		if (ch == '+')
> @@ -323,9 +305,9 @@ static void put_packet(char *buffer)
>  		 * packet.
>  		 */
>  		if (ch == '$') {
> -			kgdb_io_ops.write_char('-');
> -			if (kgdb_io_ops.flush)
> -				kgdb_io_ops.flush();
> +			kgdb_io_ops->write_char('-');
> +			if (kgdb_io_ops->flush)
> +				kgdb_io_ops->flush();
>  			return;
>  		}
>  	}
> @@ -705,10 +687,10 @@ static struct task_struct *getthread(str
>  		return current;
>  
>  	if (num_online_cpus() && (tid >= pid_max + num_online_cpus() +
> -							kgdb_ops->shadowth))
> +							arch_kgdb_ops.shadowth))
>  		return NULL;
>  
> -	if (kgdb_ops->shadowth && (tid >= pid_max + num_online_cpus())) {
> +	if (arch_kgdb_ops.shadowth && (tid >= pid_max + num_online_cpus())) {
>  		return kgdb_get_shadow_thread(regs, tid - pid_max -
>  					      num_online_cpus());
>  	}
> @@ -809,8 +791,8 @@ static void kgdb_wait(struct pt_regs *re
>  	kgdb_info[cpu].task = NULL;
>  
>  	/* fix up hardware debug registers on local cpu */
> -	if (kgdb_ops->correct_hw_break)
> -		kgdb_ops->correct_hw_break();
> +	if (arch_kgdb_ops.correct_hw_break)
> +		arch_kgdb_ops.correct_hw_break();
>  
>  	/* Signal the master CPU that we are done: */
>  	atomic_set(&cpu_in_debugger[cpu], 0);
> @@ -1013,8 +995,8 @@ int remove_all_break(void)
>  	}
>  
>  	/* Clear hardware breakpoints. */
> -	if (kgdb_ops->remove_all_hw_break)
> -		kgdb_ops->remove_all_hw_break();
> +	if (arch_kgdb_ops.remove_all_hw_break)
> +		arch_kgdb_ops.remove_all_hw_break();
>  
>  	return 0;
>  }
> @@ -1073,14 +1055,12 @@ static void kgdb_msg_write(const char *s
>   */
>  int kgdb_io_ready(int print_wait)
>  {
> -	if (!kgdb_io_ops.read_char)
> +	if (!kgdb_io_ops)
>  		return 0;
>  	if (kgdb_connected)
>  		return 1;
>  	if (atomic_read(&kgdb_setting_breakpoint))
>  		return 1;
> -	if (!attachwait)
> -		return 0;
>  	if (print_wait)
>  		printk(KERN_CRIT "KGDB: Waiting for remote debugger\n");
>  	return 1;
> @@ -1147,7 +1127,7 @@ static void gdb_cmd_getregs(struct kgdb_
>  	 * in __schedule() sleeping, since all other CPUs
>  	 * are in kgdb_wait, and thus have debuggerinfo.
>  	 */
> -	if (kgdb_ops->shadowth &&
> +	if (arch_kgdb_ops.shadowth &&
>  			ks->kgdb_usethreadid >= pid_max + num_online_cpus()) {
>  
>  		shadowregs = kgdb_shadow_regs(ks->linux_regs,
> @@ -1279,7 +1259,7 @@ static int gdb_cmd_reboot(struct kgdb_st
>  /* Handle the 'q' query packets */
>  static void gdb_cmd_query(struct kgdb_state *ks)
>  {
> -	int numshadowth = num_online_cpus() + kgdb_ops->shadowth;
> +	int numshadowth = num_online_cpus() + arch_kgdb_ops.shadowth;
>  	struct task_struct *thread;
>  	unsigned char thref[8];
>  	char *ptr;
> @@ -1430,7 +1410,7 @@ static void gdb_cmd_break(struct kgdb_st
>  	unsigned long length;
>  	int error = 0;
>  
> -	if (kgdb_ops->set_hw_breakpoint && *bpt_type >= '1') {
> +	if (arch_kgdb_ops.set_hw_breakpoint && *bpt_type >= '1') {
>  		/* Unsupported */
>  		if (*bpt_type > '4')
>  			return;
> @@ -1444,7 +1424,7 @@ static void gdb_cmd_break(struct kgdb_st
>  	 * Test if this is a hardware breakpoint, and
>  	 * if we support it:
>  	 */
> -	if (*bpt_type == '1' && !(kgdb_ops->flags & KGDB_HW_BREAKPOINT))
> +	if (*bpt_type == '1' && !(arch_kgdb_ops.flags & KGDB_HW_BREAKPOINT))
>  		/* Unsupported. */
>  		return;
>  
> @@ -1469,10 +1449,10 @@ static void gdb_cmd_break(struct kgdb_st
>  	else if (remcom_in_buffer[0] == 'z' && *bpt_type == '0')
>  		error = kgdb_remove_sw_break(addr);
>  	else if (remcom_in_buffer[0] == 'Z')
> -		error = kgdb_ops->set_hw_breakpoint(addr,
> +		error = arch_kgdb_ops.set_hw_breakpoint(addr,
>  			(int)length, *bpt_type);
>  	else if (remcom_in_buffer[0] == 'z')
> -		error = kgdb_ops->remove_hw_breakpoint(addr,
> +		error = arch_kgdb_ops.remove_hw_breakpoint(addr,
>  			(int) length, *bpt_type);
>  
>  	if (error == 0)
> @@ -1486,7 +1466,6 @@ static int gdb_cmd_exception_pass(struct
>  {
>  	/* C09 == pass exception
>  	 * C15 == detach kgdb, pass exception
> -	 * C30 == detach kgdb, stop attachwait, pass exception
>  	 */
>  	if (remcom_in_buffer[1] == '0' && remcom_in_buffer[2] == '9') {
>  
> @@ -1501,14 +1480,6 @@ static int gdb_cmd_exception_pass(struct
>  		kgdb_connected = 0;
>  		return 1;
>  
> -	} else if (remcom_in_buffer[1] == '3' && remcom_in_buffer[2] == '0') {
> -
> -		ks->pass_exception = 1;
> -		attachwait = 0;
> -		remcom_in_buffer[0] = 'D';
> -		remove_all_break();
> -		kgdb_connected = 0;
> -		return 1;
>  	} else {
>  		error_packet(remcom_out_buffer, -EINVAL);
>  		return 0;
> @@ -1557,7 +1528,7 @@ static int gdb_serial_stub(struct kgdb_s
>  	ks->kgdb_usethreadid = shadow_pid(kgdb_info[ks->cpu].task->pid);
>  	ks->pass_exception = 0;
>  
> -	while (kgdb_io_ops.read_char) {
> +	while (1) {
>  		error = 0;
>  
>  		/* Clear the out buffer. */
> @@ -1713,8 +1684,7 @@ kgdb_handle_exception(int evector, int s
>  	struct kgdb_state *ks = &kgdb_var;
>  	unsigned long flags;
>  	int error = 0;
> -	unsigned i;
> -	int cpu;
> +	int i, cpu;
>  
>  	ks->cpu			= raw_smp_processor_id();
>  	ks->all_cpus_synced	= 0;
> @@ -1788,8 +1758,8 @@ acquirelock:
>  		goto kgdb_restore;
>  
>  	/* Call the I/O driver's pre_exception routine */
> -	if (kgdb_io_ops.pre_exception)
> -		kgdb_io_ops.pre_exception();
> +	if (kgdb_io_ops->pre_exception)
> +		kgdb_io_ops->pre_exception();
>  
>  	kgdb_info[ks->cpu].debuggerinfo = ks->linux_regs;
>  	kgdb_info[ks->cpu].task = current;
> @@ -1847,15 +1817,15 @@ acquirelock:
>  	error = gdb_serial_stub(ks);
>  
>  	/* Call the I/O driver's post_exception routine */
> -	if (kgdb_io_ops.post_exception)
> -		kgdb_io_ops.post_exception();
> +	if (kgdb_io_ops->post_exception)
> +		kgdb_io_ops->post_exception();
>  
>  	kgdb_info[ks->cpu].debuggerinfo = NULL;
>  	kgdb_info[ks->cpu].task = NULL;
>  	atomic_set(&cpu_in_debugger[ks->cpu], 0);
>  
>  	if (!debugger_step || !kgdb_contthread) {
> -		for (i = 0; i < NR_CPUS; i++)
> +		for (i = NR_CPUS-1; i >= 0; i--)
>  			spin_unlock(&slave_cpu_locks[i]);
>  		/*
>  		 * Wait till all the CPUs have quit
> @@ -1968,32 +1938,10 @@ static struct console kgdbcons = {
>  };
>  #endif
>  
> -/*
> - * Initialization that needs to be done in either of our entry points.
> - */
> -static void __init kgdb_internal_init(void)
> -{
> -	int i;
> -
> -	if (kgdb_internal_init_complete)
> -		return;
> -	/* Initialize our spinlocks. */
> -	for (i = 0; i < NR_CPUS; i++)
> -		spin_lock_init(&slave_cpu_locks[i]);
> -
> -	for (i = 0; i < KGDB_MAX_BREAKPOINTS; i++)
> -		kgdb_break[i].state = BP_UNDEFINED;
> -
> -	/* Initialize the I/O handles */
> -	memset(&kgdb_io_ops_prev, 0, sizeof(kgdb_io_ops_prev));
> -
> -	kgdb_internal_init_complete = 1;
> -}
> -
>  #ifdef CONFIG_MAGIC_SYSRQ
>  static void sysrq_handle_gdb(int key, struct tty_struct *tty)
>  {
> -	if (!kgdb_io_ops.read_char) {
> +	if (!kgdb_io_ops) {
>  		printk(KERN_CRIT "ERROR: No KGDB I/O module available\n");
>  		return;
>  	}
> @@ -2061,180 +2009,74 @@ static void kgdb_unregister_hooks(void)
>  	}
>  }
>  
> -int kgdb_register_io_module(struct kgdb_io *local_kgdb_io_ops)
> +static void kgdb_initial_breakpoint(void)
>  {
> +	kgdb_break_asap = 0;
>  
> -	if (!local_kgdb_io_ops->init)
> -		return -EINVAL;
> -	if (kgdb_connected) {
> -		printk(KERN_ERR "kgdb: Cannot load I/O module while KGDB "
> -		       "connected.\n");
> -		return -EINVAL;
> -	}
> +	printk(KERN_CRIT "kgdb: Waiting for connection from remote gdb...\n");
> +	breakpoint();
> +}
>  
> -	/* Save the old values so they can be restored */
> -	if (kgdb_io_handler_cnt >= KGDB_MAX_IO_HANDLERS) {
> -		printk(KERN_ERR "kgdb: No more I/O handles available.\n");
> -		return -EINVAL;
> -	}
> +int kgdb_register_io_module(struct kgdb_io *new_kgdb_io_ops)
> +{
> +	int err;
>  
> -	/*
> -	 * Check to see if there is an existing driver and if so save its
> -	 * values.  Also check to make sure the same driver was not trying
> -	 * to re-register.
> -	 */
> -	if (kgdb_io_ops.read_char != NULL &&
> -		kgdb_io_ops.read_char != local_kgdb_io_ops->read_char) {
> -		memcpy(&kgdb_io_ops_prev[kgdb_io_handler_cnt],
> -		       &kgdb_io_ops, sizeof(struct kgdb_io));
> -		kgdb_io_handler_cnt++;
> -	}
> +	spin_lock(&kgdb_registration_lock);
>  
> -	/* Initialize the io values for this module */
> -	memcpy(&kgdb_io_ops, local_kgdb_io_ops, sizeof(struct kgdb_io));
> +	if (kgdb_io_ops) {
> +		spin_unlock(&kgdb_registration_lock);
>  
> -	/* Make the call to register kgdb if is not initialized */
> -	kgdb_register_hooks();
> +		printk(KERN_ERR "kgdb: Another I/O driver is already "
> +				"registered with KGDB.\n");
> +		return -EBUSY;
> +	}
>  
> -	return 0;
> -}
> -EXPORT_SYMBOL_GPL(kgdb_register_io_module);
> +	if (new_kgdb_io_ops->init) {
> +		err = new_kgdb_io_ops->init();
> +		if (err) {
> +			spin_unlock(&kgdb_registration_lock);
> +			return err;
> +		}
> +	}
>  
> -void kgdb_unregister_io_module(struct kgdb_io *local_kgdb_io_ops)
> -{
> -	int i;
> +	kgdb_io_ops = new_kgdb_io_ops;
>  
> -	/*
> -	 * Unregister KGDB if there were no other prior io hooks, else
> -	 * restore the io hooks.
> -	 */
> -	if (kgdb_io_handler_cnt > 0 && kgdb_io_ops_prev[0].read_char != NULL) {
> -		/*
> -		 * First check if the hook that is in use is the one being
> -		 * removed:
> -		 */
> -		if (kgdb_io_ops.read_char == local_kgdb_io_ops->read_char) {
> -			/*
> -			 * Set 'i' to the value of where the list should be
> -			 * shifed:
> -			 */
> -			i = kgdb_io_handler_cnt - 1;
> -			memcpy(&kgdb_io_ops, &kgdb_io_ops_prev[i],
> -			       sizeof(struct kgdb_io));
> -		} else {
> -			/*
> -			 * Simple case to remove an entry for an I/O handler
> -			 * that is not in use:
> -			 */
> -			for (i = 0; i < kgdb_io_handler_cnt; i++) {
> -				if (kgdb_io_ops_prev[i].read_char ==
> -				    local_kgdb_io_ops->read_char)
> -					break;
> -			}
> -		}
> +	spin_unlock(&kgdb_registration_lock);
>  
> -		/*
> -		 * Shift all the entries in the handler array so it is
> -		 * ordered from oldest to newest.
> -		 */
> -		kgdb_io_handler_cnt--;
> -		for (; i < kgdb_io_handler_cnt; i++) {
> -			memcpy(&kgdb_io_ops_prev[i], &kgdb_io_ops_prev[i + 1],
> -			       sizeof(struct kgdb_io));
> -		}
> +	printk(KERN_INFO "kgdb: Registered I/O driver %s.\n",
> +	       new_kgdb_io_ops->name);
>  
> -		/*
> -		 * Handle the case if we are on the last element and set it
> -		 * to NULL;
> -		 */
> -		memset(&kgdb_io_ops_prev[kgdb_io_handler_cnt], 0,
> -				sizeof(struct kgdb_io));
> +	/* Arm KGDB now. */
> +	kgdb_register_hooks();
>  
> -		if (kgdb_connected) {
> -			printk(KERN_ERR "kgdb: WARNING: I/O method changed "
> -			       "while kgdb was connected state.\n");
> -		}
> -	} else {
> -		/*
> -		 * KGDB is no longer able to communicate out, so
> -		 * unregister our hooks and reset state:
> -		 */
> -		kgdb_unregister_hooks();
> -		if (kgdb_connected) {
> -			printk(KERN_CRIT "kgdb: I/O module was unloaded while "
> -					"a debugging session was running.  "
> -					"KGDB will be reset.\n");
> -			if (remove_all_break() < 0)
> -				printk(KERN_CRIT "kgdb: Reset failed.\n");
> -			kgdb_connected = 0;
> -		}
> -		memset(&kgdb_io_ops, 0, sizeof(struct kgdb_io));
> -	}
> -}
> -EXPORT_SYMBOL_GPL(kgdb_unregister_io_module);
> +	if (kgdb_break_asap)
> +		kgdb_initial_breakpoint();
>  
> -static void __init kgdb_initial_breakpoint(void)
> -{
> -	printk(KERN_CRIT "kgdb: Waiting for connection from remote gdb...\n");
> -	breakpoint();
> +	return 0;
>  }
> +EXPORT_SYMBOL_GPL(kgdb_register_io_module);
>  
> -/*
> - * This function can be called very early, either via early_param() or
> - * an explicit breakpoint() early on.
> - */
> -static void __init kgdb_early_entry(void)
> +void kgdb_unregister_io_module(struct kgdb_io *old_kgdb_io_ops)
>  {
> -	/*
> -	 * Initialize the KGDB I/O module
> -	 * For early entry kgdb_io_ops.init must be defined
> -	 */
> -	if (!kgdb_io_ops.init || kgdb_io_ops.init()) {
> -		printk(KERN_INFO "kgdb: Defering I/O setup to late init.\n");
> -		return;
> -	}
> -	kgdb_internal_init();
> -	kgdb_register_io_module(&kgdb_io_ops);
> -}
> +	BUG_ON(kgdb_connected);
>  
> -/*
> - * This function will always be invoked to make sure that KGDB will grab
> - * what it needs to so that if something happens while the system is
> - * running, KGDB will get involved.  If kgdb_early_entry() has already
> - * been invoked, there is little we need to do.
> - */
> -static int __init kgdb_late_entry(void)
> -{
>  	/*
> -	 * Late entry may be the first entry, so all initialization
> -	 * routines must be called here as well as the early entry
> +	 * KGDB is no longer able to communicate out, so
> +	 * unregister our hooks and reset state.
>  	 */
> -	kgdb_internal_init();
> +	kgdb_unregister_hooks();
>  
> -	if (!kgdb_io_module_registered &&
> -		(!kgdb_io_ops.init || kgdb_io_ops.init())) {
> -		/*
> -		 * When KGDB allows I/O via modules and the core I/O init
> -		 * fails KGDB must default to defering the I/O setup, and
> -		 * appropriately print an error about it.
> -		 */
> -		printk(KERN_INFO "kgdb: Defering I/O setup to module.\n");
> -		memset(&kgdb_io_ops, 0, sizeof(struct kgdb_io));
> -		kgdb_break_asap = 0;
> -		return 0;
> -	}
> -	kgdb_register_io_module(&kgdb_io_ops);
> +	spin_lock(&kgdb_registration_lock);
>  
> -	/* Execute any late init I/O routines. */
> -	if (kgdb_io_ops.late_init)
> -		kgdb_io_ops.late_init();
> +	WARN_ON(kgdb_io_ops != old_kgdb_io_ops);
> +	kgdb_io_ops = NULL;
>  
> -	if (kgdb_break_asap)
> -		kgdb_initial_breakpoint();
> +	spin_unlock(&kgdb_registration_lock);
>  
> -	return 0;
> +	printk(KERN_INFO "kgdb: Unregistered I/O driver %s, debugger "
> +	                 "disabled.\n", old_kgdb_io_ops->name);
>  }
> -late_initcall(kgdb_late_entry);
> +EXPORT_SYMBOL_GPL(kgdb_unregister_io_module);
>  
>  /*
>   * This function will generate a breakpoint exception.  It is used at the
> @@ -2264,38 +2106,23 @@ kgdb_notify_reboot(struct notifier_block
>  	if (!kgdb_connected || atomic_read(&debugger_active) != 0)
>  		return 0;
>  
> -	if ((code == SYS_RESTART) || (code == SYS_HALT) ||
> -						(code == SYS_POWER_OFF)) {
> +	if (code == SYS_RESTART || code == SYS_HALT || code == SYS_POWER_OFF) {
>  		local_irq_save(flags);
>  		put_packet("X00");
> +		kgdb_connected = 0;
>  		local_irq_restore(flags);
>  	}
>  	return NOTIFY_DONE;
>  }
>  
> -static int __init opt_kgdb_attachwait(char *str)
> -{
> -	attachwait = 1;
> -
> -	return 0;
> -}
> -
> -static int __init opt_kgdb_enter(char *str)
> +static int __init opt_kgdb_wait(char *str)
>  {
> -	/* We've already done this by an explicit breakpoint() call. */
> -	if  (kgdb_internal_init_complete)
> -		return 0;
> -
> -	kgdb_early_entry();
> -	attachwait = 1;
> +	kgdb_break_asap = 1;
>  
>  	if (kgdb_io_module_registered)
>  		kgdb_initial_breakpoint();
> -	else
> -		kgdb_break_asap = 1;
>  
>  	return 0;
>  }
>  
> -early_param("kgdbwait", opt_kgdb_enter);
> -early_param("attachwait", opt_kgdb_attachwait);
> +early_param("kgdbwait", opt_kgdb_wait);
> Index: b/lib/Kconfig.kgdb
> ===================================================================
> --- a/lib/Kconfig.kgdb
> +++ b/lib/Kconfig.kgdb
> @@ -15,126 +15,6 @@ config KGDB_ARCH_HAS_SHADOW_INFO
>  	bool
>  	depends on KGDB
>  
> -config SERIAL_POLL
> -	bool
> -
> -choice
> -	prompt "Method for KGDB communication"
> -	depends on KGDB
> -	default KGDBOC_NOMODULE
> -	help
> -	  There are a number of different ways in which you can communicate
> -	  with KGDB.  The most common is via serial, with the 8250 driver
> -	  (should your hardware have an 8250, or ns1655x style uart).
> -	  You can elect to have one core I/O driver that is built into the
> -	  kernel for debugging as the kernel is booting, or using only
> -	  kernel modules.
> -
> -config KGDB_ONLY_MODULES
> -	bool "KGDB: Use only kernel modules for I/O"
> -	depends on MODULES
> -	help
> -	  Use only kernel modules to configure KGDB I/O after the
> -	  kernel is booted.
> -
> -config KGDB_8250_NOMODULE
> -	bool "KGDB: On generic serial port (8250)"
> -	select KGDB_8250
> -	help
> -	  Uses generic serial port (8250) to communicate with the host
> -	  GDB.  This is independent of the normal (SERIAL_8250) driver
> -	  for this chipset.
> -
> -config KGDBOC_NOMODULE
> -	bool "KGDB: On Console - in kernel"
> -	select KGDBOC
> -	select SERIAL_POLL
> -	help
> -	  Uses the SERIAL_POLL API to multiplex the console driver
> -	  output with the debugger output when the debugger is active.
> -	  To break into the debugger initially you must use the sysrq
> -	  request with the "g" for gdb.
> -
> -endchoice
> -
> -config KGDBOC
> -	tristate "KGDB: Share serial console and kgdb port" if !KGDBOC_NOMODULE
> -	depends on m && KGDB
> -	default m
> -	select SERIAL_POLL
> -	select MAGIC_SYSRQ
> -	help
> -	  Share a serial console with kgdb.  The sysrq-g must be used
> -	  to break in initially.
> -
> -config KGDB_8250
> -	tristate "KGDB: On generic serial port (8250)" if !KGDB_8250_NOMODULE
> -	depends on m && KGDB_ONLY_MODULES
> -	help
> -	  Uses generic serial port (8250) to communicate with the host
> -	  GDB.  This is independent of the normal (SERIAL_8250) driver
> -	  for this chipset.
> -
> -config KGDB_SIMPLE_SERIAL
> -	bool "Simple configuration of KGDB serial port"
> -	depends on KGDB_8250_NOMODULE
> -	default y
> -	help
> -	  If you say Y here, you will only have to pick the baud rate
> -	  and port number that you wish to use for KGDB.  Note that this
> -	  only works on architectures that register known serial ports
> -	  early on.  If you say N, you will have to provide, either here
> -	  or on the command line, the type (I/O or MMIO), IRQ and
> -	  address to use.  If in doubt, say Y.
> -
> -config KGDB_SERIAL_STATIC
> -	bool "Configure KGDB serial parameters statically"
> -	depends on KGDB_8250
> -	default n
> -	help
> -	  If you turn this on, you do not have to specify the kgdb
> -	  serial paramters via kernel boot arguments.  It also means
> -	  that kgdb will configure the serial port on boot.
> -
> -config KGDB_BAUDRATE
> -	int "Debug serial port baud rate"
> -	depends on KGDB_SERIAL_STATIC && KGDB_SIMPLE_SERIAL && KGDB_8250
> -	default "115200"
> -	help
> -	  gdb and the kernel stub need to agree on the baud rate to be
> -	  used.  Standard rates from 9600 to 115200 are allowed, and this
> -	  may be overridden via the commandline.
> -
> -config KGDB_PORT_NUM
> -	int "Serial port number for KGDB"
> -	range 0 3
> -	depends on KGDB_SERIAL_STATIC && KGDB_SIMPLE_SERIAL && KGDB_8250
> -	default "0"
> -	help
> -	  Pick the port number (0 based) for KGDB to use.
> -
> -config KGDB_8250_CONF_STRING
> -	string "Configuration string for KGDB"
> -	depends on KGDB_SERIAL_STATIC && (KGDB_8250 = y) && \
> -		!KGDB_SIMPLE_SERIAL && KGDB_8250
> -	default "io,2f8,115200,3" if X86
> -	help
> -	  The format of this string should be <io or mmio>,
> -	  <address>,<baud rate>,<irq>.  For example, on an i386 box,
> -	  to use the serial port located at 0x2f8, IRQ 3, at 115200 baud
> -	  use:  io,2f8,115200,3
> -
> -config KGDB_ATTACH_WAIT
> -	bool "KGDB: Wait for debugger to attach on an unknown exception"
> -	depends on KGDB
> -	default (KGDB_8250 = y)
> -	help
> -	  If a panic occurs, or any kind of exception, the kgdb will
> -	  stop and wait for a debugger to attach.  This sets the
> -	  default behavior for waiting for the debugger to attach.  This
> -	  value can also be changed at runtime through
> -	  /sys/module/kgdb/parameters/attachwait
> -
>  config KGDB_CONSOLE
>  	bool "KGDB: Console messages through gdb"
>  	depends on KGDB
> @@ -147,3 +27,36 @@ config KGDB_CONSOLE
>  	  to crash, and typically reboot.  For this reason, it is preferable
>  	  to use NETCONSOLE in conjunction with KGDBOE instead of
>  	  KGDB_CONSOLE.
> +
> +comment "KGDB I/O drivers"
> +	depends on KGDB
> +
> +config KGDB_8250
> +	tristate "8250/16550 and compatible serial support"
> +	depends on KGDB
> +	select SERIAL_8250
> +	default y
> +	help
> +	  Uses a 8250/16550 compatible serial ports to communicate with the
> +	  host GDB.  This is independent of the normal driver (SERIAL_8250)
> +	  for this chipset.  The port is configured via kgdb8250=<config>,
> +	  passed as kernel or module parameter, respectively.  The
> +	  configuration comes in two flavors:
> +
> +	  <io|mmio|mmap>,<address>[/<regshift>],<baud rate>,<irq>
> +	    or
> +	  ttyS<n>,<baud rate>
> +
> +	  When built into the kernel, this driver allows debugging of
> +	  the early boot process.  Note that, as long as the debugger is
> +	  attached via this driver,  the configured serial port cannot be
> +	  used by the standard 8250 driver or serial earlyprintk/earlycon.
> +
> +config KGDBOC
> +	tristate "KGDB: Share serial console and kgdb port"
> +	depends on KGDB
> +	select SERIAL_POLL
> +	select MAGIC_SYSRQ
> +	help
> +	  Share a serial console with kgdb.  The sysrq-g must be used
> +	  to break in initially.
> Index: b/drivers/serial/kgdboc.c
> ===================================================================
> --- a/drivers/serial/kgdboc.c
> +++ b/drivers/serial/kgdboc.c
> @@ -16,8 +16,8 @@
>  #include <linux/kernel.h>
>  #include <linux/kgdb.h>
>  #include <linux/tty.h>
> +#include <linux/ctype.h>
>  
> -#define NOT_CONFIGURED_STRING "not_configured"
>  #define MAX_KGDBOC_CONFIG_STR 40
>  
>  static struct kgdb_io kgdboc_io_ops;
> @@ -27,7 +27,7 @@ static int configured = -1;
>  
>  MODULE_DESCRIPTION("KGDB Console TTY Driver");
>  MODULE_LICENSE("GPL");
> -static char config[MAX_KGDBOC_CONFIG_STR] = NOT_CONFIGURED_STRING;
> +static char config[MAX_KGDBOC_CONFIG_STR];
>  static struct kparam_string kps = {
>  	.string = config,
>  	.maxlen = MAX_KGDBOC_CONFIG_STR,
> @@ -40,13 +40,9 @@ static int kgdboc_option_setup(char *opt
>  {
>  	if (strlen(opt) > MAX_KGDBOC_CONFIG_STR) {
>  		printk(KERN_ERR "kgdboc: config string too long\n");
> -		strcpy(config, NOT_CONFIGURED_STRING);
> -		return 1;
> +		return -ENOSPC;
>  	}
> -
> -	/* If we're being given a new configuration, copy it in. */
> -	if (opt != config)
> -		strcpy(config, opt);
> +	strcpy(config, opt);
>  	return 0;
>  }
>  __setup("kgdboc=", kgdboc_option_setup);
> @@ -54,18 +50,21 @@ __setup("kgdboc=", kgdboc_option_setup);
>  static int configure_kgdboc(void)
>  {
>  	struct tty_driver *p;
> -	int ret = 1;
> +	int err;
>  	char *str;
>  	int tty_line = 0;
>  
> -	kgdboc_option_setup(config);
> -	if (strcmp(config, NOT_CONFIGURED_STRING) == 0)
> -		goto err;
> +	err = kgdboc_option_setup(config);
> +	if (err || !strlen(config) || isspace(config[0]))
> +		goto noconfig;
> +
> +	err = -ENODEV;
>  
>  	/* Search through the tty devices to look for a match */
> +	// FIXME: API violation, at least missing lock protection
>  	list_for_each_entry(p, &tty_drivers, tty_drivers) {
> -		if (!(p->type == TTY_DRIVER_TYPE_SERIAL &&
> -			  strncmp(config, p->name, strlen(p->name)) == 0))
> +		if (p->type != TTY_DRIVER_TYPE_SERIAL ||
> +		    strncmp(config, p->name, strlen(p->name)) != 0)
>  			continue;
>  		str = config + strlen(p->name);
>  		tty_line = simple_strtoul(str, &str, 10);
> @@ -78,29 +77,24 @@ static int configure_kgdboc(void)
>  			p->poll_init && !p->poll_init(p, tty_line, str)) {
>  			kgdb_tty_driver = p;
>  			kgdb_tty_line = tty_line;
> -			ret = 0;
> +			err = 0;
>  			break;
>  		}
>  	}
> -	if (ret) {
> -		printk(KERN_ERR "kgdboc: invalid parmater: %s\n", config);
> -		printk(KERN_ERR "Usage kgdboc=<serial_device>[,baud]\n");
> -		goto err;
> -	}
> +	if (err)
> +		goto noconfig;
>  
> -	if (kgdb_register_io_module(&kgdboc_io_ops)) {
> -		printk(KERN_ERR "KGDB IO registration failed\n");
> -		goto err;
> -	}
> -	configured = 1;
> +	err = kgdb_register_io_module(&kgdboc_io_ops);
> +	if (err)
> +		goto noconfig;
>  
> -	printk(KERN_INFO "kgdboc: Debugging enabled\n");
> +	configured = 1;
>  	return 0;
>  
> -err:
> -	strcpy(config, NOT_CONFIGURED_STRING);
> +noconfig:
> +	config[0] = 0;
>  	configured = 0;
> -	return -EINVAL;
> +	return err;
>  
>  }
>  
> @@ -110,16 +104,13 @@ static int init_kgdboc(void)
>  	if (configured == 1)
>  		return 0;
>  
> -	if (configure_kgdboc())
> -		printk(KERN_INFO "kgdboc: Driver loaded in"
> -		" not_configured state\n");
> -
> -	return 0;
> +	return configure_kgdboc();
>  }
>  
>  static void cleanup_kgdboc(void)
>  {
> -	kgdb_unregister_io_module(&kgdboc_io_ops);
> +	if (configured == 1)
> +		kgdb_unregister_io_module(&kgdboc_io_ops);
>  }
>  
>  static int kgdboc_get_char(void)
> @@ -137,67 +128,30 @@ static void kgdboc_put_char(u8 chr)
>  static int param_set_kgdboc_var(const char *kmessage,
>  		struct kernel_param *kp)
>  {
> -	char kmessage_save[MAX_KGDBOC_CONFIG_STR];
> -	int msg_len = strlen(kmessage);
> -
> -	if (msg_len + 1 > MAX_KGDBOC_CONFIG_STR) {
> -		printk(KERN_ERR "%s: string doesn't fit in %u chars.\n",
> -		       kp->name, MAX_KGDBOC_CONFIG_STR - 1);
> +	if (strlen(kmessage) >= MAX_KGDBOC_CONFIG_STR) {
> +		printk(KERN_ERR "kgdboc: config string too long\n");
>  		return -ENOSPC;
>  	}
>  
>  	/* Only copy in the string if the init function has not run yet */
>  	if (configured < 0) {
> -		strncpy(config, kmessage, sizeof(config));
> +		strcpy(config, kmessage);
>  		return 0;
>  	}
>  
>  	if (kgdb_connected) {
>  		printk(KERN_ERR "kgdboc: Cannot reconfigure while KGDB is "
>  				"connected.\n");
> -		return 0;
> +		return -EBUSY;
>  	}
>  
> -	/* Start the reconfiguration process by saving the old string */
> -	strncpy(kmessage_save, config, sizeof(kmessage_save));
> -
> -
> -	/* Copy in the new param and strip out invalid characters so we
> -	 * can optionally specify the MAC.
> -	 */
> -	strncpy(config, kmessage, sizeof(config));
> -	msg_len--;
> -	while (msg_len > 0 &&
> -			(config[msg_len] < ',' || config[msg_len] > 'f')) {
> -		config[msg_len] = '\0';
> -		msg_len--;
> -	}
> -
> -	/* Check to see if we are unconfiguring the io module and that it
> -	 * was in a fully configured state, as this is the only time that
> -	 * netpoll_cleanup should get called
> -	 */
> -	if (configured == 1 && strcmp(config, NOT_CONFIGURED_STRING) == 0) {
> -		printk(KERN_INFO "kgdboc: reverting to unconfigured state\n");
> -		cleanup_kgdboc();
> -		return 0;
> -	} else
> -		/* Go and configure with the new params. */
> -		configure_kgdboc();
> +	strcpy(config, kmessage);
>  
>  	if (configured == 1)
> -		return 0;
> +		cleanup_kgdboc();
>  
> -	/* If the new string was invalid, revert to the previous state, which
> -	 * is at a minimum not_configured. */
> -	strncpy(config, kmessage_save, sizeof(config));
> -	if (strcmp(kmessage_save, NOT_CONFIGURED_STRING) != 0) {
> -		printk(KERN_INFO "kgdboc: reverting to prior configuration\n");
> -		/* revert back to the original config */
> -		strncpy(config, kmessage_save, sizeof(config));
> -		configure_kgdboc();
> -	}
> -	return 0;
> +	/* Go and configure with the new params. */
> +	return configure_kgdboc();
>  }
>  
>  static void kgdboc_pre_exp_handler(void)
> @@ -215,9 +169,9 @@ static void kgdboc_post_exp_handler(void
>  }
>  
>  static struct kgdb_io kgdboc_io_ops = {
> +	.name = "kgdboc",
>  	.read_char = kgdboc_get_char,
>  	.write_char = kgdboc_put_char,
> -	.init = init_kgdboc,
>  	.pre_exception = kgdboc_pre_exp_handler,
>  	.post_exception = kgdboc_post_exp_handler,
>  };
> @@ -225,4 +179,4 @@ static struct kgdb_io kgdboc_io_ops = {
>  module_init(init_kgdboc);
>  module_exit(cleanup_kgdboc);
>  module_param_call(kgdboc, param_set_kgdboc_var, param_get_string, &kps, 0644);
> -MODULE_PARM_DESC(kgdboc, " kgdboc=<serial_device>[,baud]\n");
> +MODULE_PARM_DESC(kgdboc, "<serial_device>[,baud]");
> --
> To unsubscribe from this list: send the line "unsubscribe linux-kernel" in
> the body of a message to majordomo@xxxxxxxxxxxxxxx
> More majordomo info at  http://vger.kernel.org/majordomo-info.html
> Please read the FAQ at  http://www.tux.org/lkml/
> 

As one of the users who likes to see kgdb in mainline, can I ask what
should I expect, when do you think it will be ready for mainline inclusion?

Best regards,
	Maxim Levitsky
--
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