diff -ru /usr/src/sys/ddb/db_ps.c sys/ddb/db_ps.c
--- /usr/src/sys/ddb/db_ps.c	Mon Oct 15 22:19:41 2007
+++ sys/ddb/db_ps.c	Mon Dec 24 23:28:29 2007
@@ -280,10 +280,133 @@
 	db_printf("\n");
 }
 
+struct tdflagmap {
+	int val;
+	char *name;
+};
+
+/*
+ * Mapping between TDF_* flags and their ASCII representation.
+ * Keep those values synchronized with proc.h.
+ */
+static struct tdflagmap tdf_map[] = {
+#define TDF_FLAGMAPADD(x)	\
+	{ (x), #x }
+	TDF_FLAGMAPADD(TDF_BORROWING),
+	TDF_FLAGMAPADD(TDF_INPANIC),
+	TDF_FLAGMAPADD(TDF_INMEM),
+	TDF_FLAGMAPADD(TDF_SINTR),
+	TDF_FLAGMAPADD(TDF_TIMEOUT),
+	TDF_FLAGMAPADD(TDF_IDLETD),
+	TDF_FLAGMAPADD(TDF_SELECT),
+	TDF_FLAGMAPADD(TDF_SLEEPABORT),
+	TDF_FLAGMAPADD(TDF_KTH_SUSP),
+	TDF_FLAGMAPADD(TDF_UBORROWING),
+	TDF_FLAGMAPADD(TDF_BOUNDARY),
+	TDF_FLAGMAPADD(TDF_ASTPENDING),
+	TDF_FLAGMAPADD(TDF_TIMOFAIL),
+	TDF_FLAGMAPADD(TDF_INTERRUPT),
+	TDF_FLAGMAPADD(TDF_UPIBLOCKED),
+	TDF_FLAGMAPADD(TDF_UNUSED15),
+	TDF_FLAGMAPADD(TDF_NEEDRESCHED),
+	TDF_FLAGMAPADD(TDF_NEEDSIGCHK),
+	TDF_FLAGMAPADD(TDF_XSIG),
+	TDF_FLAGMAPADD(TDF_UNUSED19),
+	TDF_FLAGMAPADD(TDF_THRWAKEUP),
+	TDF_FLAGMAPADD(TDF_DBSUSPEND),
+	TDF_FLAGMAPADD(TDF_SWAPINREQ),
+	TDF_FLAGMAPADD(TDF_UNUSED23),
+	TDF_FLAGMAPADD(TDF_SCHED0),
+	TDF_FLAGMAPADD(TDF_SCHED1),
+	TDF_FLAGMAPADD(TDF_SCHED2),
+	TDF_FLAGMAPADD(TDF_SCHED3),
+	TDF_FLAGMAPADD(TDF_ALRMPEND),
+	TDF_FLAGMAPADD(TDF_PROFPEND),
+	TDF_FLAGMAPADD(TDF_MACPEND),
+#undef TDF_FLAGMAPADD
+};
+
+/*
+ * Mapping between TDP_* flags and their ASCII representation.
+ * Keep those values synchronized with proc.h.
+ */
+static struct tdflagmap tdp_map[] = {
+#define TDP_FLAGMAPADD(x)	\
+	{ (x), #x }
+	TDP_FLAGMAPADD(TDP_OLDMASK),
+	TDP_FLAGMAPADD(TDP_INKTR),
+	TDP_FLAGMAPADD(TDP_INKTRACE),
+	TDP_FLAGMAPADD(TDP_UPCALLING),
+	TDP_FLAGMAPADD(TDP_COWINPROGRESS),
+	TDP_FLAGMAPADD(TDP_ALTSTACK),
+	TDP_FLAGMAPADD(TDP_DEADLKTREAT),
+	TDP_FLAGMAPADD(TDP_SA),
+	TDP_FLAGMAPADD(TDP_NOSLEEPING),
+	TDP_FLAGMAPADD(TDP_OWEUPC),
+	TDP_FLAGMAPADD(TDP_ITHREAD),
+	TDP_FLAGMAPADD(TDP_CAN_UNBIND),
+	TDP_FLAGMAPADD(TDP_SCHED1),
+	TDP_FLAGMAPADD(TDP_SCHED2),
+	TDP_FLAGMAPADD(TDP_SCHED3),
+	TDP_FLAGMAPADD(TDP_SCHED4),
+	TDP_FLAGMAPADD(TDP_GEOM),
+	TDP_FLAGMAPADD(TDP_SOFTDEP),
+	TDP_FLAGMAPADD(TDP_NORUNNINGBUF),
+	TDP_FLAGMAPADD(TDP_WAKEUP),
+	TDP_FLAGMAPADD(TDP_INBDFLUSH),
+	TDP_FLAGMAPADD(TDP_KTHREAD),
+	TDP_FLAGMAPADD(TDP_CALLCHAIN),
+#undef TDP_FLAGMAPADD
+};
+
+enum {
+	TDFLAG_TD_FLAGS,
+	TDFLAG_TD_PFLAGS,
+};
+
+static void
+flags_externalize(int which, char *buf, int bufsize, int flags)
+{
+	int fst, i, sz;
+	struct tdflagmap *map;
+	char *s;
+
+	KASSERT(buf != NULL, ("buf == NULL"));
+	
+	bzero(buf, bufsize);
+	snprintf(buf, bufsize, "(%#x) ", flags);
+	if (which == TDFLAG_TD_FLAGS) {
+		map = tdf_map;
+		sz = sizeof(tdf_map) / sizeof(tdf_map[0]);
+	} else if (which == TDFLAG_TD_PFLAGS) {
+		map = tdp_map;
+		sz = sizeof(tdp_map) / sizeof(tdp_map[0]);
+	} else {
+		snprintf(buf, bufsize, "<UNKNOWN>\n");
+		return;
+	}
+	fst = 1;
+	for (i = 0; i < sz; i++) {
+		if (flags & map[i].val) {
+			if (fst == 1)
+				s = "<";
+			else
+				s = ",";
+			strlcat(buf, s, bufsize);
+			strlcat(buf, map[i].name, bufsize); 
+			fst = 0;
+		}
+	}
+	if (fst == 0)
+		/* At least one known flag present */
+		strlcat(buf, ">", bufsize);
+}
+
 DB_SHOW_COMMAND(thread, db_show_thread)
 {
 	struct thread *td;
 	boolean_t comma;
+	char flstr[512];
 
 	/* Determine which thread to examine. */
 	if (have_addr)
@@ -297,8 +420,12 @@
 		db_printf(" name: %s\n", td->td_name);
 	db_printf(" stack: %p-%p\n", (void *)td->td_kstack,
 	    (void *)(td->td_kstack + td->td_kstack_pages * PAGE_SIZE - 1));
-	db_printf(" flags: %#x ", td->td_flags);
-	db_printf(" pflags: %#x\n", td->td_pflags);
+	flags_externalize(TDFLAG_TD_FLAGS, flstr, sizeof(flstr),
+	    td->td_flags);
+	db_printf(" flags: %s\n", flstr);
+	flags_externalize(TDFLAG_TD_PFLAGS, flstr, sizeof(flstr),
+	    td->td_pflags);
+	db_printf(" pflags: %s\n", flstr);
 	db_printf(" state: ");
 	switch (td->td_state) {
 	case TDS_INACTIVE:
diff -ru /usr/src/sys/i386/i386/local_apic.c sys/i386/i386/local_apic.c
--- /usr/src/sys/i386/i386/local_apic.c	Mon Oct 15 22:21:10 2007
+++ sys/i386/i386/local_apic.c	Mon Dec 24 23:39:24 2007
@@ -928,6 +928,11 @@
 DB_SHOW_COMMAND(lapic, db_show_lapic)
 {
 	uint32_t v;
+	
+	if (lapic_paddr == 0) {
+		db_printf("Local APIC is not used.\n");
+		return;
+	}
 
 	db_printf("lapic ID = %d\n", lapic_id());
 	v = lapic->version;
diff -ru /usr/src/sys/kern/subr_lock.c sys/kern/subr_lock.c
--- /usr/src/sys/kern/subr_lock.c	Sun Nov 18 21:15:57 2007
+++ sys/kern/subr_lock.c	Mon Dec 24 23:14:11 2007
@@ -236,8 +236,10 @@
 	struct lock_object *lock;
 	struct lock_class *class;
 
-	if (!have_addr)
+	if (!have_addr) {
+		db_printf("Usage: show lock <addr>\n");
 		return;
+	}
 	lock = (struct lock_object *)addr;
 	if (LO_CLASSINDEX(lock) > LOCK_CLASS_MAX) {
 		db_printf("Unknown lock class: %d\n", LO_CLASSINDEX(lock));
diff -ru /usr/src/sys/kern/subr_rman.c sys/kern/subr_rman.c
--- /usr/src/sys/kern/subr_rman.c	Mon Apr 23 16:58:18 2007
+++ sys/kern/subr_rman.c	Mon Dec 24 23:19:03 2007
@@ -923,7 +923,7 @@
 
 	if (db_pager_quit)
 		return;
-	db_printf("rman: %s\n", rm->rm_descr);
+	db_printf("rman: %p (%s)\n", rm, rm->rm_descr);
 	db_printf("    0x%lx-0x%lx (full range)\n", rm->rm_start, rm->rm_end);
 	TAILQ_FOREACH(r, &rm->rm_list, r_link) {
 		if (r->r_dev != NULL) {
@@ -947,6 +947,8 @@
 
 	if (have_addr)
 		dump_rman((struct rman *)addr);
+	else
+		db_printf("Usage: show rman addr\n");
 }
 
 DB_SHOW_COMMAND(allrman, db_show_all_rman)
diff -ru /usr/src/sys/kern/subr_sleepqueue.c sys/kern/subr_sleepqueue.c
--- /usr/src/sys/kern/subr_sleepqueue.c	Sun Nov 18 21:15:57 2007
+++ sys/kern/subr_sleepqueue.c	Mon Dec 24 23:15:32 2007
@@ -911,8 +911,11 @@
 	void *wchan;
 	int i;
 
-	if (!have_addr)
+	if (!have_addr) {
+		db_printf("Usage: show sleepqueue <addr>\n");
+		db_printf("       show sleepq <addr>\n");
 		return;
+	}
 
 	/*
 	 * First, see if there is an active sleep queue for the wait channel
diff -ru /usr/src/sys/kern/subr_turnstile.c sys/kern/subr_turnstile.c
--- /usr/src/sys/kern/subr_turnstile.c	Sun Nov 18 21:15:57 2007
+++ sys/kern/subr_turnstile.c	Mon Dec 24 23:17:33 2007
@@ -1049,8 +1049,10 @@
 	struct lock_object *lock;
 	int i;
 
-	if (!have_addr)
+	if (!have_addr) {
+		db_printf("Usage: show turnstile <addr>\n");
 		return;
+	}
 
 	/*
 	 * First, see if there is an active turnstile for the lock indicated
diff -ru /usr/src/sys/kern/vfs_subr.c sys/kern/vfs_subr.c
--- /usr/src/sys/kern/vfs_subr.c	Wed Dec  5 12:00:30 2007
+++ sys/kern/vfs_subr.c	Mon Dec 24 23:16:53 2007
@@ -2699,8 +2699,10 @@
 {
 	struct vnode *vp;
 
-	if (!have_addr)
+	if (!have_addr) {
+		db_printf("Usage: show vnode <addr>\n");
 		return;
+	}
 	vp = (struct vnode *)addr;
 	vn_printf(vp, "vnode ");
 }
diff -ru /usr/src/sys/vm/vm_map.c sys/vm/vm_map.c
--- /usr/src/sys/vm/vm_map.c	Sun Nov 18 21:16:07 2007
+++ sys/vm/vm_map.c	Mon Dec 24 23:13:06 2007
@@ -3363,9 +3363,15 @@
 DB_SHOW_COMMAND(map, vm_map_print)
 {
 	static int nlines;
-	/* XXX convert args. */
-	vm_map_t map = (vm_map_t)addr;
-	boolean_t full = have_addr;
+	vm_map_t map;
+	boolean_t full;
+
+	if (!have_addr) {
+		db_printf("Usage: show map <addr>\n");
+		return;
+	}
+	map = (vm_map_t)addr;
+	full = have_addr;
 
 	vm_map_entry_t entry;
 
diff -ru /usr/src/sys/vm/vm_object.c sys/vm/vm_object.c
--- /usr/src/sys/vm/vm_object.c	Sun Nov 18 21:16:07 2007
+++ sys/vm/vm_object.c	Mon Dec 24 23:20:15 2007
@@ -2071,10 +2071,18 @@
 DB_SHOW_COMMAND(object, vm_object_print_static)
 {
 	/* XXX convert args. */
-	vm_object_t object = (vm_object_t)addr;
-	boolean_t full = have_addr;
+	vm_object_t object;
+	boolean_t full;
 
 	vm_page_t p;
+
+	if (!have_addr) {
+		db_printf("Usage: show object <addr>\n");
+		return;
+	}
+	object = (vm_object_t)addr;
+	full = have_addr;
+
 
 	/* XXX count is an (unused) arg.  Avoid shadowing it. */
 #define	count	was_count