Usability non-serial console sessions.

index 4802eb5..5eb7e23 100644
@@ -580,8 +580,8 @@ int vkdb_printf(const char *fmt, va_list ap)
 		__acquire(kdb_printf_lock);
 	}
 
-	diag = kdbgetintenv("LINES", &linecount);
-	if (diag || linecount <= 1)
+	linecount = kdb_lines;
+	if (linecount <= 1)
 		linecount = 24;
 
 	diag = kdbgetintenv("LOGGING", &logging);

index 63786e7..37f9d45 100644
@@ -60,6 +60,7 @@ atomic_t kdb_event;
 int kdb_initial_cpu = -1;	/* cpu number that owns kdb */
 int kdb_nextline = 1;
 int kdb_state;			/* General KDB state */
+int kdb_lines = 0;		/* Lines displayed at once */
 
 struct task_struct *kdb_current_task;
 EXPORT_SYMBOL(kdb_current_task);

@@ -386,6 +387,18 @@ int kdb_set(int argc, const char **argv)
 			| (debugflags << KDB_DEBUG_FLAG_SHIFT);
 
 		return 0;
+	} else if (strcmp(argv[1], "LINES") == 0) {
+		int lines;
+		char *cp;
+
+		lines = simple_strtol(argv[2], &cp, 0);
+		if (cp == argv[2]) {
+			kdb_printf("kdb: illegal LINES value '%s'\n",
+				   argv[2]);
+			return 0;
+		}
+		kdb_lines = lines;
+		return 0;
 	}
 
 	/*

@@ -721,8 +734,11 @@ static int kdb_defcmd(int argc, const char **argv)
  */
 static int kdb_exec_defcmd(int argc, const char **argv)
 {
-	int i, ret;
+	int i;
+	int oldlines;
 	struct defcmd_set *s;
+	int ret = 0;
+
 	if (argc != 0)
 		return KDB_ARGCOUNT;
 	for (s = defcmd_set, i = 0; i < defcmd_set_count; ++i, ++s) {

@@ -734,6 +750,9 @@ static int kdb_exec_defcmd(int argc, const char **argv)
 			   argv[0]);
 		return KDB_NOTIMP;
 	}
+
+	/* command might have overridden LINES */
+	oldlines = kdb_lines;
 	for (i = 0; i < s->count; ++i) {
 		/* Recursive use of kdb_parse, do not use argv after
 		 * this point */

@@ -741,9 +760,10 @@ static int kdb_exec_defcmd(int argc, const char **argv)
 		kdb_printf("[%s]kdb> %s\n", s->name, s->command[i]);
 		ret = kdb_parse(s->command[i]);
 		if (ret)
-			return ret;
+			break;
 	}
-	return 0;
+	kdb_lines = oldlines;
+	return ret;
 }
 
 /* Command history */

@@ -2026,6 +2046,9 @@ static int kdb_env(int argc, const char **argv)
 	if (KDB_DEBUG(MASK))
 		kdb_printf("KDBFLAGS=0x%x\n", kdb_flags);
 
+	if (kdb_lines)
+		kdb_printf("LINES=%d\n", kdb_lines);
+
 	return 0;
 }
 

index e381d10..41a221f 100644
@@ -154,6 +154,7 @@ extern int kdb_state;
 #define KDB_STATE_CLEAR(flag) ((void)(kdb_state &= ~KDB_STATE_##flag))
 
 extern int kdb_nextline; /* Current number of lines displayed */
+extern int kdb_lines;    /* Limit on number of lines displayed at once. */
 
 typedef struct _kdb_bp {
 	unsigned long	bp_addr;	/* Address breakpoint is present at */

index 37f9d45..da26843 100644
@@ -391,6 +391,13 @@ int kdb_set(int argc, const char **argv)
 		int lines;
 		char *cp;
 
+		/*
+                 * We are running a custom command,
+		 * and want to use current limit on
+		 * lines displayed.
+		 */
+		if (KDB_STATE(RO_LINES))
+			return 0;
 		lines = simple_strtol(argv[2], &cp, 0);
 		if (cp == argv[2]) {
 			kdb_printf("kdb: illegal LINES value '%s'\n",

@@ -674,6 +681,7 @@ static int kdb_defcmd2(const char *cmdstr, const char *argv0)
 
 static int kdb_defcmd(int argc, const char **argv)
 {
+	static char usage[] = " [-b]";
 	struct defcmd_set *save_defcmd_set = defcmd_set, *s;
 	if (defcmd_in_progress) {
 		kdb_printf("kdb: nested defcmd detected, assuming missing "

@@ -703,13 +711,24 @@ static int kdb_defcmd(int argc, const char **argv)
 	}
 	memcpy(defcmd_set, save_defcmd_set,
 	       defcmd_set_count * sizeof(*defcmd_set));
-	kfree(save_defcmd_set);
 	s = defcmd_set + defcmd_set_count;
 	memset(s, 0, sizeof(*s));
 	s->usable = 1;
 	s->name = kdb_strdup(argv[1], GFP_KDB);
-	s->usage = kdb_strdup(argv[2], GFP_KDB);
+	s->usage = kdb_strdup_extra(argv[2],
+				    sizeof(usage) - 1,
+				    GFP_KDB);
 	s->help = kdb_strdup(argv[3], GFP_KDB);
+	if (!s->name ||
+	    !s->usage ||
+	    !s->help) {
+		kdb_printf("Could not allocate defcmd entry members for %s\n",
+			   argv[1]);
+		kfree(defcmd_set);
+		defcmd_set = save_defcmd_set;
+		return KDB_NOTIMP;
+	}
+	kfree(save_defcmd_set);
 	if (s->usage[0] == '"') {
 		strcpy(s->usage, s->usage+1);
 		s->usage[strlen(s->usage)-1] = '\0';

@@ -718,6 +737,15 @@ static int kdb_defcmd(int argc, const char **argv)
 		strcpy(s->help, s->help+1);
 		s->help[strlen(s->help)-1] = '\0';
 	}
+
+	/*
+	 * Don't print leading space before [-b]
+	 * if usage was empty.
+	 */
+	if (s->usage[0] == '\0')
+		strcat(s->usage, usage + 1);
+	else
+		strcat(s->usage, usage);
 	++defcmd_set_count;
 	defcmd_in_progress = 1;
 	return 0;

@@ -739,8 +767,9 @@ static int kdb_exec_defcmd(int argc, const char **argv)
 	struct defcmd_set *s;
 	int ret = 0;
 
-	if (argc != 0)
+	if (argc > 1)
 		return KDB_ARGCOUNT;
+
 	for (s = defcmd_set, i = 0; i < defcmd_set_count; ++i, ++s) {
 		if (strcmp(s->name, argv[0]) == 0)
 			break;

@@ -751,8 +780,10 @@ static int kdb_exec_defcmd(int argc, const char **argv)
 		return KDB_NOTIMP;
 	}
 
-	/* command might have overridden LINES */
+	if (!strcmp(argv[1], "-b"))
+		KDB_STATE_SET(RO_LINES);
 	oldlines = kdb_lines;
+
 	for (i = 0; i < s->count; ++i) {
 		/* Recursive use of kdb_parse, do not use argv after
 		 * this point */

@@ -762,7 +793,10 @@ static int kdb_exec_defcmd(int argc, const char **argv)
 		if (ret)
 			break;
 	}
+
+	/* command might have overridden LINES */
 	kdb_lines = oldlines;
+	KDB_STATE_CLEAR(RO_LINES);
 	return ret;
 }
 

index 41a221f..99ed959 100644
@@ -112,6 +112,7 @@ extern int kdbgetsymval(const char *, kdb_symtab_t *);
 extern int kdbnearsym(unsigned long, kdb_symtab_t *);
 extern void kdbnearsym_cleanup(void);
 extern char *kdb_strdup(const char *str, gfp_t type);
+extern char *kdb_strdup_extra(const char *str, unsigned extra, gfp_t type);
 extern void kdb_symbol_print(unsigned long, const kdb_symtab_t *, unsigned int);
 
 /* Routine for debugging the debugger state. */

@@ -146,6 +147,8 @@ extern int kdb_state;
 #define KDB_STATE_KEXEC		0x00040000	/* kexec issued */
 #define KDB_STATE_DOING_KGDB	0x00080000	/* kgdb enter now issued */
 #define KDB_STATE_KGDB_TRANS	0x00200000	/* Transition to kgdb */
+#define KDB_STATE_RO_LINES	0x00400000	/* If LINES is allowed to be set
+                                                 * within a defcmd command */
 #define KDB_STATE_ARCH		0xff000000	/* Reserved for arch
 						 * specific use */
 

index 7d6fb40..8562932 100644
@@ -294,6 +294,25 @@ void kdb_symbol_print(unsigned long addr, const kdb_symtab_t *symtab_p,
 }
 
 /*
+ * kdb_strdup_extra - kdb strdup-like routine, that simplifies
+ *                    strdup+strcat-like usage.
+ * Inputs:
+ *	str	The string to duplicate.
+ *	extra	Extra length to allocate for.
+ *	type	Flags to kmalloc for the new string.
+ * Returns:
+ *	Address of the new string, NULL if storage could not be allocated.
+ */
+char *kdb_strdup_extra(const char *str, unsigned extra, gfp_t type)
+{
+	int n = strlen(str) + extra + 1;
+	char *s = kmalloc(n, type);
+	if (!s)
+		return NULL;
+	return strcpy(s, str);
+}
+
+/*
  * kdb_strdup - kdb equivalent of strdup, for disasm code.
  * Inputs:
  *	str	The string to duplicate.

@@ -306,11 +325,7 @@ void kdb_symbol_print(unsigned long addr, const kdb_symtab_t *symtab_p,
  */
 char *kdb_strdup(const char *str, gfp_t type)
 {
-	int n = strlen(str)+1;
-	char *s = kmalloc(n, type);
-	if (!s)
-		return NULL;
-	return strcpy(s, str);
+	return kdb_strdup_extra(str, 0, type);
 }
 
 /*