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Commit 4aad8f51 authored by Jason Wessel's avatar Jason Wessel
Browse files

kdb: Add kdb kernel module sample 



Add an example of how to add a dynamic kdb shell command via a kernel
module.

Signed-off-by: default avatarJason Wessel <jason.wessel@windriver.com>
parent 12ba8d1e

Documentation/DocBook/kgdb.tmpl

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@@ -710,7 +710,18 @@ Task Addr Pid Parent [*] cpu State Thread Command 
        <listitem><para>A simple shell</para></listitem>

        <listitem><para>The kdb core command set</para></listitem>

        <listitem><para>A registration API to register additional kdb shell commands.</para>

        <para>A good example of a self-contained kdb module is the "ftdump" command for dumping the ftrace buffer.  See: kernel/trace/trace_kdb.c</para></listitem>

	<itemizedlist>

        <listitem><para>A good example of a self-contained kdb module

        is the "ftdump" command for dumping the ftrace buffer.  See:

        kernel/trace/trace_kdb.c</para></listitem>

        <listitem><para>For an example of how to dynamically register

        a new kdb command you can build the kdb_hello.ko kernel module

        from samples/kdb/kdb_hello.c.  To build this example you can

        set CONFIG_SAMPLES=y and CONFIG_SAMPLE_KDB=m in your kernel

        config.  Later run "modprobe kdb_hello" and the next time you

        enter the kdb shell, you can run the "hello"

        command.</para></listitem>

	</itemizedlist></listitem>

        <listitem><para>The implementation for kdb_printf() which

        emits messages directly to I/O drivers, bypassing the kernel

        log.</para></listitem>

samples/Kconfig

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@@ -54,4 +54,11 @@ config SAMPLE_KFIFO 


	  If in doubt, say "N" here.



config SAMPLE_KDB

	tristate "Build kdb command exmaple -- loadable modules only"

	depends on KGDB_KDB && m

	help

	  Build an example of how to dynamically add the hello

	  command to the kdb shell.



endif # SAMPLES

samples/Makefile

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# Makefile for Linux samples code



obj-$(CONFIG_SAMPLES)	+= kobject/ kprobes/ tracepoints/ trace_events/ \

			   hw_breakpoint/ kfifo/
 
			   hw_breakpoint/ kfifo/ kdb/

samples/kdb/Makefile

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obj-$(CONFIG_SAMPLE_KDB) += kdb_hello.o

samples/kdb/kdb_hello.c

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/*

 * Created by: Jason Wessel <jason.wessel@windriver.com>

 *

 * Copyright (c) 2010 Wind River Systems, Inc.  All Rights Reserved.

 *

 * 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/module.h>

#include <linux/kdb.h>



/*

 * All kdb shell command call backs receive argc and argv, where

 * argv[0] is the command the end user typed

 */

static int kdb_hello_cmd(int argc, const char **argv)

{

	if (argc > 1)

		return KDB_ARGCOUNT;



	if (argc)

		kdb_printf("Hello %s.\n", argv[1]);

	else

		kdb_printf("Hello world!\n");



	return 0;

}





static int __init kdb_hello_cmd_init(void)

{

	/*

	 * Registration of a dynamically added kdb command is done with

	 * kdb_register() with the arguments being:

	 *   1: The name of the shell command

	 *   2: The function that processes the command

	 *   3: Description of the usage of any arguments

	 *   4: Descriptive text when you run help

	 *   5: Number of characters to complete the command

	 *      0 == type the whole command

	 *      1 == match both "g" and "go" for example

	 */

	kdb_register("hello", kdb_hello_cmd, "[string]",

		     "Say Hello World or Hello [string]", 0);

	return 0;

}



static void __exit kdb_hello_cmd_exit(void)

{

	kdb_unregister("hello");

}



module_init(kdb_hello_cmd_init);

module_exit(kdb_hello_cmd_exit);



MODULE_AUTHOR("WindRiver");

MODULE_DESCRIPTION("KDB example to add a hello command");

MODULE_LICENSE("GPL");