Merge branch 'for_linus' of git://git.kernel.org/pub/scm/linux/kernel/git/jwessel/linux-2.6-kgdb

* 'for_linus' of git://git.kernel.org/pub/scm/linux/kernel/git/jwessel/linux-2.6-kgdb:
kgdb,ppc: Individual register get/set for ppc
kgdbts: prevent re-entry to kgdbts before it unregisters
debug_core,x86,blackfin: Clean up hw debug disable API
kdb: Fix early debugging crash regression
kgdb,arm: fix register dump
kdb: fix per_cpu command to remove supress mask
kdb: Add kdb kernel module sample

Documentation/DocBook/kgdb.tmpl

···
         <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>

arch/arm/include/asm/kgdb.h

···
 #define _GP_REGS		16
 #define _FP_REGS		8
 #define _EXTRA_REGS		2
-#define DBG_MAX_REG_NUM		(_GP_REGS + (_FP_REGS * 3) + _EXTRA_REGS)
+#define GDB_MAX_REGS		(_GP_REGS + (_FP_REGS * 3) + _EXTRA_REGS)
+#define DBG_MAX_REG_NUM		(_GP_REGS + _FP_REGS + _EXTRA_REGS)
 
 #define KGDB_MAX_NO_CPUS	1
 #define BUFMAX			400
···
 #define _SPT			13
 #define _LR			14
 #define _PC			15
-#define _CPSR			(DBG_MAX_REG_NUM - 1)
+#define _CPSR			(GDB_MAX_REGS - 1)
 
 /*
  * So that we can denote the end of a frame for tracing,

arch/arm/kernel/kgdb.c

···
 		return;
 
 	/* Initialize to zero */
-	for (regno = 0; regno < DBG_MAX_REG_NUM; regno++)
+	for (regno = 0; regno < GDB_MAX_REGS; regno++)
 		gdb_regs[regno] = 0;
 
 	/* Otherwise, we have only some registers from switch_to() */

arch/blackfin/kernel/kgdb.c

···
 	}
 }
 
-void kgdb_disable_hw_debug(struct pt_regs *regs)
+static void bfin_disable_hw_debug(struct pt_regs *regs)
 {
 	/* Disable hardware debugging while we are in kgdb */
 	bfin_write_WPIACTL(0);
···
 #endif
 	.set_hw_breakpoint = bfin_set_hw_break,
 	.remove_hw_breakpoint = bfin_remove_hw_break,
+	.disable_hw_break = bfin_disable_hw_debug,
 	.remove_all_hw_break = bfin_remove_all_hw_break,
 	.correct_hw_break = bfin_correct_hw_break,
 };

arch/powerpc/include/asm/kgdb.h

···
 	asm(".long 0x7d821008"); /* twge r2, r2 */
 }
 #define CACHE_FLUSH_IS_SAFE	1
+#define DBG_MAX_REG_NUM     70
 
 /* The number bytes of registers we have to save depends on a few
  * things.  For 64bit we default to not including vector registers and

arch/powerpc/kernel/kgdb.c

···
 	ptr = (unsigned long *)ptr32; \
 	} while (0)
 
-
-void pt_regs_to_gdb_regs(unsigned long *gdb_regs, struct pt_regs *regs)
-{
-	unsigned long *ptr = gdb_regs;
-	int reg;
-
-	memset(gdb_regs, 0, NUMREGBYTES);
-
-	for (reg = 0; reg < 32; reg++)
-		PACK64(ptr, regs->gpr[reg]);
-
-#ifdef CONFIG_FSL_BOOKE
-#ifdef CONFIG_SPE
-	for (reg = 0; reg < 32; reg++)
-		PACK64(ptr, current->thread.evr[reg]);
-#else
-	ptr += 32;
-#endif
-#else
-	/* fp registers not used by kernel, leave zero */
-	ptr += 32 * 8 / sizeof(long);
-#endif
-
-	PACK64(ptr, regs->nip);
-	PACK64(ptr, regs->msr);
-	PACK32(ptr, regs->ccr);
-	PACK64(ptr, regs->link);
-	PACK64(ptr, regs->ctr);
-	PACK32(ptr, regs->xer);
-
-	BUG_ON((unsigned long)ptr >
-	       (unsigned long)(((void *)gdb_regs) + NUMREGBYTES));
-}
-
 void sleeping_thread_to_gdb_regs(unsigned long *gdb_regs, struct task_struct *p)
 {
 	struct pt_regs *regs = (struct pt_regs *)(p->thread.ksp +
···
 	       (unsigned long)(((void *)gdb_regs) + NUMREGBYTES));
 }
 
-#define UNPACK64(dest, ptr) do { dest = *(ptr++); } while (0)
-
-#define UNPACK32(dest, ptr) do {       \
-	u32 *ptr32;                   \
-	ptr32 = (u32 *)ptr;           \
-	dest = *(ptr32++);            \
-	ptr = (unsigned long *)ptr32; \
-	} while (0)
-
-void gdb_regs_to_pt_regs(unsigned long *gdb_regs, struct pt_regs *regs)
-{
-	unsigned long *ptr = gdb_regs;
-	int reg;
-
-	for (reg = 0; reg < 32; reg++)
-		UNPACK64(regs->gpr[reg], ptr);
+#define GDB_SIZEOF_REG sizeof(unsigned long)
+#define GDB_SIZEOF_REG_U32 sizeof(u32)
 
 #ifdef CONFIG_FSL_BOOKE
-#ifdef CONFIG_SPE
-	for (reg = 0; reg < 32; reg++)
-		UNPACK64(current->thread.evr[reg], ptr);
+#define GDB_SIZEOF_FLOAT_REG sizeof(unsigned long)
 #else
-	ptr += 32;
-#endif
-#else
-	/* fp registers not used by kernel, leave zero */
-	ptr += 32 * 8 / sizeof(int);
+#define GDB_SIZEOF_FLOAT_REG sizeof(u64)
 #endif
 
-	UNPACK64(regs->nip, ptr);
-	UNPACK64(regs->msr, ptr);
-	UNPACK32(regs->ccr, ptr);
-	UNPACK64(regs->link, ptr);
-	UNPACK64(regs->ctr, ptr);
-	UNPACK32(regs->xer, ptr);
+struct dbg_reg_def_t dbg_reg_def[DBG_MAX_REG_NUM] =
+{
+	{ "r0", GDB_SIZEOF_REG, offsetof(struct pt_regs, gpr[0]) },
+	{ "r1", GDB_SIZEOF_REG, offsetof(struct pt_regs, gpr[1]) },
+	{ "r2", GDB_SIZEOF_REG, offsetof(struct pt_regs, gpr[2]) },
+	{ "r3", GDB_SIZEOF_REG, offsetof(struct pt_regs, gpr[3]) },
+	{ "r4", GDB_SIZEOF_REG, offsetof(struct pt_regs, gpr[4]) },
+	{ "r5", GDB_SIZEOF_REG, offsetof(struct pt_regs, gpr[5]) },
+	{ "r6", GDB_SIZEOF_REG, offsetof(struct pt_regs, gpr[6]) },
+	{ "r7", GDB_SIZEOF_REG, offsetof(struct pt_regs, gpr[7]) },
+	{ "r8", GDB_SIZEOF_REG, offsetof(struct pt_regs, gpr[8]) },
+	{ "r9", GDB_SIZEOF_REG, offsetof(struct pt_regs, gpr[9]) },
+	{ "r10", GDB_SIZEOF_REG, offsetof(struct pt_regs, gpr[10]) },
+	{ "r11", GDB_SIZEOF_REG, offsetof(struct pt_regs, gpr[11]) },
+	{ "r12", GDB_SIZEOF_REG, offsetof(struct pt_regs, gpr[12]) },
+	{ "r13", GDB_SIZEOF_REG, offsetof(struct pt_regs, gpr[13]) },
+	{ "r14", GDB_SIZEOF_REG, offsetof(struct pt_regs, gpr[14]) },
+	{ "r15", GDB_SIZEOF_REG, offsetof(struct pt_regs, gpr[15]) },
+	{ "r16", GDB_SIZEOF_REG, offsetof(struct pt_regs, gpr[16]) },
+	{ "r17", GDB_SIZEOF_REG, offsetof(struct pt_regs, gpr[17]) },
+	{ "r18", GDB_SIZEOF_REG, offsetof(struct pt_regs, gpr[18]) },
+	{ "r19", GDB_SIZEOF_REG, offsetof(struct pt_regs, gpr[19]) },
+	{ "r20", GDB_SIZEOF_REG, offsetof(struct pt_regs, gpr[20]) },
+	{ "r21", GDB_SIZEOF_REG, offsetof(struct pt_regs, gpr[21]) },
+	{ "r22", GDB_SIZEOF_REG, offsetof(struct pt_regs, gpr[22]) },
+	{ "r23", GDB_SIZEOF_REG, offsetof(struct pt_regs, gpr[23]) },
+	{ "r24", GDB_SIZEOF_REG, offsetof(struct pt_regs, gpr[24]) },
+	{ "r25", GDB_SIZEOF_REG, offsetof(struct pt_regs, gpr[25]) },
+	{ "r26", GDB_SIZEOF_REG, offsetof(struct pt_regs, gpr[26]) },
+	{ "r27", GDB_SIZEOF_REG, offsetof(struct pt_regs, gpr[27]) },
+	{ "r28", GDB_SIZEOF_REG, offsetof(struct pt_regs, gpr[28]) },
+	{ "r29", GDB_SIZEOF_REG, offsetof(struct pt_regs, gpr[29]) },
+	{ "r30", GDB_SIZEOF_REG, offsetof(struct pt_regs, gpr[30]) },
+	{ "r31", GDB_SIZEOF_REG, offsetof(struct pt_regs, gpr[31]) },
 
-	BUG_ON((unsigned long)ptr >
-	       (unsigned long)(((void *)gdb_regs) + NUMREGBYTES));
+	{ "f0", GDB_SIZEOF_FLOAT_REG, 0 },
+	{ "f1", GDB_SIZEOF_FLOAT_REG, 1 },
+	{ "f2", GDB_SIZEOF_FLOAT_REG, 2 },
+	{ "f3", GDB_SIZEOF_FLOAT_REG, 3 },
+	{ "f4", GDB_SIZEOF_FLOAT_REG, 4 },
+	{ "f5", GDB_SIZEOF_FLOAT_REG, 5 },
+	{ "f6", GDB_SIZEOF_FLOAT_REG, 6 },
+	{ "f7", GDB_SIZEOF_FLOAT_REG, 7 },
+	{ "f8", GDB_SIZEOF_FLOAT_REG, 8 },
+	{ "f9", GDB_SIZEOF_FLOAT_REG, 9 },
+	{ "f10", GDB_SIZEOF_FLOAT_REG, 10 },
+	{ "f11", GDB_SIZEOF_FLOAT_REG, 11 },
+	{ "f12", GDB_SIZEOF_FLOAT_REG, 12 },
+	{ "f13", GDB_SIZEOF_FLOAT_REG, 13 },
+	{ "f14", GDB_SIZEOF_FLOAT_REG, 14 },
+	{ "f15", GDB_SIZEOF_FLOAT_REG, 15 },
+	{ "f16", GDB_SIZEOF_FLOAT_REG, 16 },
+	{ "f17", GDB_SIZEOF_FLOAT_REG, 17 },
+	{ "f18", GDB_SIZEOF_FLOAT_REG, 18 },
+	{ "f19", GDB_SIZEOF_FLOAT_REG, 19 },
+	{ "f20", GDB_SIZEOF_FLOAT_REG, 20 },
+	{ "f21", GDB_SIZEOF_FLOAT_REG, 21 },
+	{ "f22", GDB_SIZEOF_FLOAT_REG, 22 },
+	{ "f23", GDB_SIZEOF_FLOAT_REG, 23 },
+	{ "f24", GDB_SIZEOF_FLOAT_REG, 24 },
+	{ "f25", GDB_SIZEOF_FLOAT_REG, 25 },
+	{ "f26", GDB_SIZEOF_FLOAT_REG, 26 },
+	{ "f27", GDB_SIZEOF_FLOAT_REG, 27 },
+	{ "f28", GDB_SIZEOF_FLOAT_REG, 28 },
+	{ "f29", GDB_SIZEOF_FLOAT_REG, 29 },
+	{ "f30", GDB_SIZEOF_FLOAT_REG, 30 },
+	{ "f31", GDB_SIZEOF_FLOAT_REG, 31 },
+
+	{ "pc", GDB_SIZEOF_REG, offsetof(struct pt_regs, nip) },
+	{ "msr", GDB_SIZEOF_REG, offsetof(struct pt_regs, msr) },
+	{ "cr", GDB_SIZEOF_REG_U32, offsetof(struct pt_regs, ccr) },
+	{ "lr", GDB_SIZEOF_REG, offsetof(struct pt_regs, link) },
+	{ "ctr", GDB_SIZEOF_REG_U32, offsetof(struct pt_regs, ctr) },
+	{ "xer", GDB_SIZEOF_REG, offsetof(struct pt_regs, xer) },
+};
+
+char *dbg_get_reg(int regno, void *mem, struct pt_regs *regs)
+{
+	if (regno >= DBG_MAX_REG_NUM || regno < 0)
+		return NULL;
+
+	if (regno < 32 || regno >= 64)
+		/* First 0 -> 31 gpr registers*/
+		/* pc, msr, ls... registers 64 -> 69 */
+		memcpy(mem, (void *)regs + dbg_reg_def[regno].offset,
+				dbg_reg_def[regno].size);
+
+	if (regno >= 32 && regno < 64) {
+		/* FP registers 32 -> 63 */
+#if defined(CONFIG_FSL_BOOKE) && defined(CONFIG_SPE)
+		if (current)
+			memcpy(mem, current->thread.evr[regno-32],
+					dbg_reg_def[regno].size);
+#else
+		/* fp registers not used by kernel, leave zero */
+		memset(mem, 0, dbg_reg_def[regno].size);
+#endif
+	}
+
+	return dbg_reg_def[regno].name;
+}
+
+int dbg_set_reg(int regno, void *mem, struct pt_regs *regs)
+{
+	if (regno >= DBG_MAX_REG_NUM || regno < 0)
+		return -EINVAL;
+
+	if (regno < 32 || regno >= 64)
+		/* First 0 -> 31 gpr registers*/
+		/* pc, msr, ls... registers 64 -> 69 */
+		memcpy((void *)regs + dbg_reg_def[regno].offset, mem,
+				dbg_reg_def[regno].size);
+
+	if (regno >= 32 && regno < 64) {
+		/* FP registers 32 -> 63 */
+#if defined(CONFIG_FSL_BOOKE) && defined(CONFIG_SPE)
+		memcpy(current->thread.evr[regno-32], mem,
+				dbg_reg_def[regno].size);
+#else
+		/* fp registers not used by kernel, leave zero */
+		return 0;
+#endif
+	}
+
+	return 0;
 }
 
 void kgdb_arch_set_pc(struct pt_regs *regs, unsigned long pc)

arch/x86/kernel/kgdb.c

···
  *	disable hardware debugging while it is processing gdb packets or
  *	handling exception.
  */
-void kgdb_disable_hw_debug(struct pt_regs *regs)
+static void kgdb_disable_hw_debug(struct pt_regs *regs)
 {
 	int i;
 	int cpu = raw_smp_processor_id();
···
 	.flags			= KGDB_HW_BREAKPOINT,
 	.set_hw_breakpoint	= kgdb_set_hw_break,
 	.remove_hw_breakpoint	= kgdb_remove_hw_break,
+	.disable_hw_break	= kgdb_disable_hw_debug,
 	.remove_all_hw_break	= kgdb_remove_all_hw_break,
 	.correct_hw_break	= kgdb_correct_hw_break,
 };

drivers/misc/kgdbts.c

···
 	return configure_kgdbts();
 }
 
-static void cleanup_kgdbts(void)
-{
-	if (configured == 1)
-		kgdb_unregister_io_module(&kgdbts_io_ops);
-}
-
 static int kgdbts_get_char(void)
 {
 	int val = 0;
···
 		return 0;
 	}
 
-	if (kgdb_connected) {
-		printk(KERN_ERR
-	       "kgdbts: Cannot reconfigure while KGDB is connected.\n");
-
+	if (configured == 1) {
+		printk(KERN_ERR "kgdbts: ERROR: Already configured and running.\n");
 		return -EBUSY;
 	}
 
···
 	/* Chop out \n char as a result of echo */
 	if (config[len - 1] == '\n')
 		config[len - 1] = '\0';
-
-	if (configured == 1)
-		cleanup_kgdbts();
 
 	/* Go and configure with the new params. */
 	return configure_kgdbts();
···
 };
 
 module_init(init_kgdbts);
-module_exit(cleanup_kgdbts);
 module_param_call(kgdbts, param_set_kgdbts_var, param_get_string, &kps, 0644);
 MODULE_PARM_DESC(kgdbts, "<A|V1|V2>[F#|S#][N#]");
 MODULE_DESCRIPTION("KGDB Test Suite");

include/linux/kgdb.h

···
  */
 extern int kgdb_skipexception(int exception, struct pt_regs *regs);
 
-/**
- *	kgdb_disable_hw_debug - (optional) Disable hardware debugging hook
- *	@regs: Current &struct pt_regs.
- *
- *	This function will be called if the particular architecture must
- *	disable hardware debugging while it is processing gdb packets or
- *	handling exception.
- */
-extern void kgdb_disable_hw_debug(struct pt_regs *regs);
-
 struct tasklet_struct;
 struct task_struct;
 struct uart_port;
···
  * breakpoint.
  * @remove_hw_breakpoint: Allow an architecture to specify how to remove a
  * hardware breakpoint.
+ * @disable_hw_break: Allow an architecture to specify how to disable
+ * hardware breakpoints for a single cpu.
  * @remove_all_hw_break: Allow an architecture to specify how to remove all
  * hardware breakpoints.
  * @correct_hw_break: Allow an architecture to specify how to correct the
···
 	int	(*remove_breakpoint)(unsigned long, char *);
 	int	(*set_hw_breakpoint)(unsigned long, int, enum kgdb_bptype);
 	int	(*remove_hw_breakpoint)(unsigned long, int, enum kgdb_bptype);
+	void	(*disable_hw_break)(struct pt_regs *regs);
 	void	(*remove_all_hw_break)(void);
 	void	(*correct_hw_break)(void);
 };

kernel/debug/debug_core.c

···
 	return 0;
 }
 
-/**
- *	kgdb_disable_hw_debug - Disable hardware debugging while we in kgdb.
- *	@regs: Current &struct pt_regs.
- *
- *	This function will be called if the particular architecture must
- *	disable hardware debugging while it is processing gdb packets or
- *	handling exception.
- */
-void __weak kgdb_disable_hw_debug(struct pt_regs *regs)
-{
-}
-
 /*
  * Some architectures need cache flushes when we set/clear a
  * breakpoint:
···
 		atomic_inc(&masters_in_kgdb);
 	else
 		atomic_inc(&slaves_in_kgdb);
-	kgdb_disable_hw_debug(ks->linux_regs);
+
+	if (arch_kgdb_ops.disable_hw_break)
+		arch_kgdb_ops.disable_hw_break(regs);
 
 acquirelock:
 	/*

kernel/debug/kdb/kdb_main.c

···
 		/* special case below */
 	} else {
 		kdb_printf("\nEntering kdb (current=0x%p, pid %d) ",
-			   kdb_current, kdb_current->pid);
+			   kdb_current, kdb_current ? kdb_current->pid : 0);
 #if defined(CONFIG_SMP)
 		kdb_printf("on processor %d ", raw_smp_processor_id());
 #endif
···
  */
 static int kdb_per_cpu(int argc, const char **argv)
 {
-	char buf[256], fmtstr[64];
-	kdb_symtab_t symtab;
-	cpumask_t suppress = CPU_MASK_NONE;
-	int cpu, diag;
-	unsigned long addr, val, bytesperword = 0, whichcpu = ~0UL;
+	char fmtstr[64];
+	int cpu, diag, nextarg = 1;
+	unsigned long addr, symaddr, val, bytesperword = 0, whichcpu = ~0UL;
 
 	if (argc < 1 || argc > 3)
 		return KDB_ARGCOUNT;
 
-	snprintf(buf, sizeof(buf), "per_cpu__%s", argv[1]);
-	if (!kdbgetsymval(buf, &symtab)) {
-		kdb_printf("%s is not a per_cpu variable\n", argv[1]);
-		return KDB_BADADDR;
-	}
+	diag = kdbgetaddrarg(argc, argv, &nextarg, &symaddr, NULL, NULL);
+	if (diag)
+		return diag;
+
 	if (argc >= 2) {
 		diag = kdbgetularg(argv[2], &bytesperword);
 		if (diag)
···
 #define KDB_PCU(cpu) 0
 #endif
 #endif
-
 	for_each_online_cpu(cpu) {
+		if (KDB_FLAG(CMD_INTERRUPT))
+			return 0;
+
 		if (whichcpu != ~0UL && whichcpu != cpu)
 			continue;
-		addr = symtab.sym_start + KDB_PCU(cpu);
+		addr = symaddr + KDB_PCU(cpu);
 		diag = kdb_getword(&val, addr, bytesperword);
 		if (diag) {
 			kdb_printf("%5d " kdb_bfd_vma_fmt0 " - unable to "
 				   "read, diag=%d\n", cpu, addr, diag);
 			continue;
 		}
-#ifdef	CONFIG_SMP
-		if (!val) {
-			cpu_set(cpu, suppress);
-			continue;
-		}
-#endif	/* CONFIG_SMP */
 		kdb_printf("%5d ", cpu);
 		kdb_md_line(fmtstr, addr,
 			bytesperword == KDB_WORD_SIZE,
 			1, bytesperword, 1, 1, 0);
 	}
-	if (cpus_weight(suppress) == 0)
-		return 0;
-	kdb_printf("Zero suppressed cpu(s):");
-	for (cpu = first_cpu(suppress); cpu < num_possible_cpus();
-	     cpu = next_cpu(cpu, suppress)) {
-		kdb_printf(" %d", cpu);
-		if (cpu == num_possible_cpus() - 1 ||
-		    next_cpu(cpu, suppress) != cpu + 1)
-			continue;
-		while (cpu < num_possible_cpus() &&
-		       next_cpu(cpu, suppress) == cpu + 1)
-			++cpu;
-		kdb_printf("-%d", cpu);
-	}
-	kdb_printf("\n");
-
 #undef KDB_PCU
-
 	return 0;
 }
 

samples/Kconfig

···
 
 	  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

···
 # Makefile for Linux samples code
 
 obj-$(CONFIG_SAMPLES)	+= kobject/ kprobes/ tracepoints/ trace_events/ \
-			   hw_breakpoint/ kfifo/
+			   hw_breakpoint/ kfifo/ kdb/

samples/kdb/Makefile

···
+obj-$(CONFIG_SAMPLE_KDB) += kdb_hello.o

samples/kdb/kdb_hello.c

···
+/*
+ * Created by: Jason Wessel <[e-mail]>
+ *
+ * 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");