diff --git a/drivers/log/log.c b/drivers/log/log.c
index 45b5e620d..df267aec2 100644
--- a/drivers/log/log.c
+++ b/drivers/log/log.c
@@ -99,6 +99,9 @@ static int sef_cb_init_fresh(int UNUSED(type), sef_init_info_t *UNUSED(info))
  	logdevices[i].log_source = NONE;
   }
 
+  /* Register for diagnostics notifications. */
+  sys_diagctl_register();
+
   return(OK);
 }
 
diff --git a/drivers/tty/tty.c b/drivers/tty/tty.c
index b0c910a6f..bdfdd142e 100644
--- a/drivers/tty/tty.c
+++ b/drivers/tty/tty.c
@@ -336,6 +336,9 @@ static int sef_cb_init_fresh(int UNUSED(type), sef_init_info_t *UNUSED(info))
   /* Final one-time keyboard initialization. */
   kb_init_once();
 
+  /* Register for diagnostics notifications. */
+  sys_diagctl_register();
+
   return(OK);
 }
 
diff --git a/include/minix/com.h b/include/minix/com.h
index 8534feb7d..3b659eeae 100644
--- a/include/minix/com.h
+++ b/include/minix/com.h
@@ -589,6 +589,8 @@
 #define DIAGCTL_ARG2		m1_i2
 #define DIAGCTL_CODE_DIAG	1	/* Print diagnostics. */
 #define DIAGCTL_CODE_STACKTRACE	2	/* Print process stack. */
+#define DIAGCTL_CODE_REGISTER	3	/* Register for diagnostic signals */
+#define DIAGCTL_CODE_UNREGISTER	4	/* Unregister for diagnostic signals */
 #define DIAG_BUFSIZE	(80*25)
 
 /* Field names for SYS_VTIMER. */
diff --git a/include/minix/config.h b/include/minix/config.h
index 2ccdec4a0..926c64df6 100644
--- a/include/minix/config.h
+++ b/include/minix/config.h
@@ -35,17 +35,6 @@
 /* DMA_SECTORS may be increased to speed up DMA based drivers. */
 #define DMA_SECTORS        1	/* DMA buffer size (must be >= 1) */
 
-/* Which processes should receive diagnostics from the kernel and system? 
- * Directly sending it to TTY only displays the output. Sending it to the
- * log driver will cause the diagnostics to be buffered and displayed.
- * Messages are sent by src/lib/sysutil/kputc.c to these processes, in
- * the order of this array, which must be terminated by NONE. This is used
- * by drivers and servers that printf().
- * The kernel does this for its own kprintf() in kernel/utility.c, also using
- * this array, but a slightly different mechanism.
- */
-#define OUTPUT_PROCS_ARRAY	{ TTY_PROC_NR, LOG_PROC_NR, NONE }
-
 /* NR_CONS, NR_RS_LINES, and NR_PTYS determine the number of terminals the
  * system can handle.
  */
diff --git a/include/minix/syslib.h b/include/minix/syslib.h
index dad156080..17b5812a1 100644
--- a/include/minix/syslib.h
+++ b/include/minix/syslib.h
@@ -69,8 +69,6 @@ int sys_vmctl_enable_paging(void * data);
 int sys_readbios(phys_bytes address, void *buf, size_t size);
 int sys_settime(int now, clockid_t clk_id, time_t sec, long nsec);
 int sys_stime(time_t boottime);
-int sys_diagctl(int ctl, char *arg1, int arg2);
-int sys_diagctl_stacktrace(endpoint_t who);
 int sys_vmctl_get_mapping(int index, phys_bytes *addr, phys_bytes *len,
 	int *flags);
 int sys_vmctl_reply_mapping(int index, vir_bytes addr);
@@ -159,6 +157,17 @@ int sys_umap_data_fb(endpoint_t proc_ep, vir_bytes vir_addr, vir_bytes
 int sys_umap_remote(endpoint_t proc_ep, endpoint_t grantee, int seg,
 	vir_bytes vir_addr, vir_bytes bytes, phys_bytes *phys_addr);
 
+/* Shorthands for sys_diagctl() system call. */
+#define sys_diagctl_diag(buf,len) \
+	sys_diagctl(DIAGCTL_CODE_DIAG, buf, len)
+#define sys_diagctl_stacktrace(ep) \
+	sys_diagctl(DIAGCTL_CODE_STACKTRACE, NULL, ep)
+#define sys_diagctl_register()	\
+	sys_diagctl(DIAGCTL_CODE_REGISTER, NULL, 0)
+#define sys_diagctl_unregister() \
+	sys_diagctl(DIAGCTL_CODE_UNREGISTER, NULL, 0)
+int sys_diagctl(int ctl, char *arg1, int arg2);
+
 /* Shorthands for sys_getinfo() system call. */
 #define sys_getkinfo(dst)	sys_getinfo(GET_KINFO, dst, 0,0,0)
 #define sys_getloadinfo(dst)	sys_getinfo(GET_LOADINFO, dst, 0,0,0)
diff --git a/kernel/arch/earm/pre_init.c b/kernel/arch/earm/pre_init.c
index 4bb133c4d..73947905d 100644
--- a/kernel/arch/earm/pre_init.c
+++ b/kernel/arch/earm/pre_init.c
@@ -411,7 +411,7 @@ kinfo_t *pre_init(int argc, char **argv)
  * ensure this). The following methods are used in that context. Once we jump to kmain they are no
  * longer used and the "real" implementations are visible
  */
-int send_sig(endpoint_t proc_nr, int sig_nr) { return 0; }
+void send_diag_sig(void) { }
 void minix_shutdown(minix_timer_t *t) { arch_shutdown(RBT_PANIC); }
 void busy_delay_ms(int x) { }
 int raise(int n) { panic("raise(%d)\n", n); }
diff --git a/kernel/arch/i386/pre_init.c b/kernel/arch/i386/pre_init.c
index 2a9967ac8..165e6d57b 100644
--- a/kernel/arch/i386/pre_init.c
+++ b/kernel/arch/i386/pre_init.c
@@ -245,7 +245,7 @@ kinfo_t *pre_init(u32_t magic, u32_t ebx)
 	return &kinfo;
 }
 
-int send_sig(endpoint_t proc_nr, int sig_nr) { return 0; }
+void send_diag_sig(void) { }
 void minix_shutdown(minix_timer_t *t) { arch_shutdown(RBT_PANIC); }
 void busy_delay_ms(int x) { }
 int raise(int sig) { panic("raise(%d)\n", sig); }
diff --git a/kernel/priv.h b/kernel/priv.h
index 204dacd46..0bdd00949 100644
--- a/kernel/priv.h
+++ b/kernel/priv.h
@@ -45,6 +45,8 @@ struct priv {
   minix_timer_t s_alarm_timer;	/* synchronous alarm timer */
   reg_t *s_stack_guard;		/* stack guard word for kernel tasks */
 
+  char s_diag_sig;		/* send a SIGKMESS when diagnostics arrive? */
+
   int s_nr_io_range;		/* allowed I/O ports */
   struct io_range s_io_tab[NR_IO_RANGE];
 
diff --git a/kernel/proto.h b/kernel/proto.h
index ac2b55625..8de351bc2 100644
--- a/kernel/proto.h
+++ b/kernel/proto.h
@@ -91,6 +91,7 @@ void fill_sendto_mask(const struct proc *rc, sys_map_t *map);
 int send_sig(endpoint_t proc_nr, int sig_nr);
 void cause_sig(proc_nr_t proc_nr, int sig_nr);
 void sig_delay_done(struct proc *rp);
+void send_diag_sig(void);
 void kernel_call(message *m_user, struct proc * caller);
 void system_init(void);
 void clear_endpoint(struct proc *rc);
diff --git a/kernel/system.c b/kernel/system.c
index 084d47760..a76d6af69 100644
--- a/kernel/system.c
+++ b/kernel/system.c
@@ -18,6 +18,7 @@
  *   send_sig:		send a signal directly to a system process
  *   cause_sig:		take action to cause a signal to occur via a signal mgr
  *   sig_delay_done:	tell PM that a process is not sending
+ *   send_diag_sig:	send a diagnostics signal to interested processes
  *   get_randomness:	accumulate randomness in a buffer
  *   clear_endpoint:	remove a process' ability to send and receive messages
  *   sched_proc:	schedule a process
@@ -464,6 +465,25 @@ void sig_delay_done(struct proc *rp)
   cause_sig(proc_nr(rp), SIGSNDELAY);
 }
 
+/*===========================================================================*
+ *				send_diag_sig				     *
+ *===========================================================================*/
+void send_diag_sig(void)
+{
+/* Send a SIGKMESS signal to all processes in receiving updates about new
+ * diagnostics messages.
+ */
+  struct priv *privp;
+  endpoint_t ep;
+
+  for (privp = BEG_PRIV_ADDR; privp < END_PRIV_ADDR; privp++) {
+	if (privp->s_proc_nr != NONE && privp->s_diag_sig == TRUE) {
+		ep = proc_addr(privp->s_proc_nr)->p_endpoint;
+		send_sig(ep, SIGKMESS);
+	}
+  }
+}
+
 /*===========================================================================*
  *			         clear_ipc				     *
  *===========================================================================*/
diff --git a/kernel/system/do_diagctl.c b/kernel/system/do_diagctl.c
index a75051b9d..788dddba3 100644
--- a/kernel/system/do_diagctl.c
+++ b/kernel/system/do_diagctl.c
@@ -42,6 +42,21 @@ int do_diagctl(struct proc * caller, message * m_ptr)
 		return EINVAL;
 	proc_stacktrace(proc_addr(proc_nr));
 	return OK;
+    case DIAGCTL_CODE_REGISTER:
+	if (!(priv(caller)->s_flags & SYS_PROC))
+		return EPERM;
+	priv(caller)->s_diag_sig = TRUE;
+	/* If the message log is not empty, send a first notification
+	 * immediately. After bootup the log is basically never empty.
+	 */
+	if (kmess.km_size > 0 && !kinfo.do_serial_debug)
+		send_sig(caller->p_endpoint, SIGKMESS);
+	return OK;
+    case DIAGCTL_CODE_UNREGISTER:
+	if (!(priv(caller)->s_flags & SYS_PROC))
+		return EPERM;
+	priv(caller)->s_diag_sig = FALSE;
+	return OK;
     default:
 	printf("do_diagctl: invalid request %d\n", m_ptr->DIAGCTL_CODE);
         return(EINVAL);
diff --git a/kernel/system/do_privctl.c b/kernel/system/do_privctl.c
index 2d3cb15b5..8b7dba019 100644
--- a/kernel/system/do_privctl.c
+++ b/kernel/system/do_privctl.c
@@ -116,6 +116,7 @@ int do_privctl(struct proc * caller, message * m_ptr)
 	reset_kernel_timer(&priv(rp)->s_alarm_timer);	/* - alarm */
 	priv(rp)->s_asyntab= -1;			/* - asynsends */
 	priv(rp)->s_asynsize= 0;
+	priv(rp)->s_diag_sig = FALSE;		/* no request for diag sigs */
 
 	/* Set defaults for privilege bitmaps. */
 	priv(rp)->s_flags= DSRV_F;           /* privilege flags */
diff --git a/kernel/system/do_update.c b/kernel/system/do_update.c
index 38341b32a..d0f7ceb90 100644
--- a/kernel/system/do_update.c
+++ b/kernel/system/do_update.c
@@ -161,6 +161,7 @@ static void adjust_priv_slot(struct priv *privp, struct priv *from_privp)
   privp->s_int_pending = from_privp->s_int_pending;
   privp->s_sig_pending = from_privp->s_sig_pending;
   privp->s_alarm_timer = from_privp->s_alarm_timer;
+  privp->s_diag_sig = from_privp->s_diag_sig;
 }
 
 /*===========================================================================*
diff --git a/kernel/utility.c b/kernel/utility.c
index f112ee07a..d5fdbdb02 100644
--- a/kernel/utility.c
+++ b/kernel/utility.c
@@ -55,7 +55,7 @@ void kputc(c)
 int c;					/* character to append */
 {
 /* Accumulate a single character for a kernel message. Send a notification
- * to the output driver if an END_OF_KMESS is encountered. 
+ * to the output drivers if an END_OF_KMESS is encountered.
  */
   if (c != END_OF_KMESS) {
       int maxblpos = sizeof(kmess.kmess_buf) - 2;
@@ -75,18 +75,9 @@ int c;					/* character to append */
       	memmove(kmess.kmess_buf,
 		kmess.kmess_buf+1, sizeof(kmess.kmess_buf)-1);
       } else kmess.blpos++;
-  } else {
-      int p;
-      endpoint_t outprocs[] = OUTPUT_PROCS_ARRAY;
-      if(!(kinfo.minix_panicing || kinfo.do_serial_debug)) {
-	      for(p = 0; outprocs[p] != NONE; p++) {
-		 if(isokprocn(outprocs[p])) {
-       	    send_sig(outprocs[p], SIGKMESS);
-		 }
-      	}
-     }
+  } else if (!(kinfo.minix_panicing || kinfo.do_serial_debug)) {
+	send_diag_sig();
   }
-  return;
 }
 
 /*===========================================================================*
diff --git a/lib/libsys/kputc.c b/lib/libsys/kputc.c
index 5e3fbbf40..7a2106dcc 100644
--- a/lib/libsys/kputc.c
+++ b/lib/libsys/kputc.c
@@ -20,7 +20,7 @@ void kputc(int c)
   static int buf_count;		/* # characters in the buffer */
 
   if ((c == 0 && buf_count > 0) || buf_count == sizeof(print_buf)) {
-	sys_diagctl(DIAGCTL_CODE_DIAG, print_buf, buf_count);
+	sys_diagctl_diag(print_buf, buf_count);
 	buf_count = 0;
   }
   if (c != 0) { 
diff --git a/lib/libsys/sys_diagctl.c b/lib/libsys/sys_diagctl.c
index a74777c49..bf7ca5d8c 100644
--- a/lib/libsys/sys_diagctl.c
+++ b/lib/libsys/sys_diagctl.c
@@ -11,9 +11,3 @@ int sys_diagctl(int code, char *arg1, int arg2)
 
   return(_kernel_call(SYS_DIAGCTL, &m));
 }
-
-int sys_diagctl_stacktrace(endpoint_t ep)
-{
-  return sys_diagctl(DIAGCTL_CODE_STACKTRACE, NULL, ep);
-}
-