Index: uspace/drv/char/ns8250/cyclic_buffer.h
===================================================================
--- uspace/drv/char/ns8250/cyclic_buffer.h	(revision 135486df91381258aa51c130b7b463fc4ff5e0a8)
+++ uspace/drv/char/ns8250/cyclic_buffer.h	(revision 7a7b8efa5c1cacbcce13573da5c694507aebb49c)
@@ -36,5 +36,5 @@
 #define CYCLIC_BUFFER_H_
 
-#define BUF_LEN 256
+#define BUF_LEN 4096
 
 typedef struct cyclic_buffer {
Index: uspace/drv/char/ns8250/ns8250.c
===================================================================
--- uspace/drv/char/ns8250/ns8250.c	(revision 135486df91381258aa51c130b7b463fc4ff5e0a8)
+++ uspace/drv/char/ns8250/ns8250.c	(revision 7a7b8efa5c1cacbcce13573da5c694507aebb49c)
@@ -82,4 +82,6 @@
 /** Interrupt ID Register definition. */
 #define	NS8250_IID_ACTIVE	(1 << 0)
+#define NS8250_IID_CAUSE_MASK 0x0e
+#define NS8250_IID_CAUSE_RXSTATUS 0x06
 
 /** FIFO Control Register definition. */
@@ -179,4 +181,6 @@
 	/** The fibril mutex for synchronizing the access to the device. */
 	fibril_mutex_t mutex;
+	/** Indicates that some data has become available */
+	fibril_condvar_t input_buffer_available;
 	/** True if device is removed. */
 	bool removed;
@@ -238,7 +242,11 @@
 {
 	ns8250_t *ns = NS8250(fun);
-	int ret = EOK;
+	int ret = 0;
+	
+	if (count == 0) return 0;
 	
 	fibril_mutex_lock(&ns->mutex);
+	while (buf_is_empty(&ns->input_buffer))
+		fibril_condvar_wait(&ns->input_buffer_available, &ns->mutex);
 	while (!buf_is_empty(&ns->input_buffer) && (size_t)ret < count) {
 		buf[ret] = (char)buf_pop_front(&ns->input_buffer);
@@ -460,5 +468,5 @@
 {
 	/* Interrupt when data received. */
-	pio_write_8(&regs->ier, NS8250_IER_RXREADY);
+	pio_write_8(&regs->ier, NS8250_IER_RXREADY | NS8250_IER_RXSTATUS);
 	pio_write_8(&regs->mcr, NS8250_MCR_DTR | NS8250_MCR_RTS 
 	    | NS8250_MCR_OUT2);
@@ -499,4 +507,7 @@
 	async_exchange_end(exch);
 
+	/* Read LSR to clear possible previous LSR interrupt */
+	pio_read_8(&ns->regs->lsr);
+
 	/* Enable interrupt on the serial port. */
 	ns8250_port_interrupts_enable(ns->regs);
@@ -695,8 +706,11 @@
 	/* 8 bits, no parity, two stop bits. */
 	ns8250_port_set_com_props(ns->regs, SERIAL_NO_PARITY, 8, 2);
-	/* Enable FIFO, clear them, with 14-byte threshold. */
+	/*
+	 * Enable FIFO, clear them, with 4-byte threshold for greater
+	 * reliability.
+	 */
 	pio_write_8(&ns->regs->iid, NS8250_FCR_FIFOENABLE
-	    | NS8250_FCR_RXFIFORESET | NS8250_FCR_TXFIFORESET 
-	    | NS8250_FCR_RXTRIGGERLOW | NS8250_FCR_RXTRIGGERHI);
+	    | NS8250_FCR_RXFIFORESET | NS8250_FCR_TXFIFORESET
+	    | NS8250_FCR_RXTRIGGERLOW);
 	/*
 	 * RTS/DSR set (Request to Send and Data Terminal Ready lines enabled),
@@ -731,7 +745,6 @@
 	bool cont = true;
 	
+	fibril_mutex_lock(&ns->mutex);
 	while (cont) {
-		fibril_mutex_lock(&ns->mutex);
-		
 		cont = ns8250_received(regs);
 		if (cont) {
@@ -739,24 +752,28 @@
 			
 			if (ns->client_connected) {
+				bool buf_was_empty = buf_is_empty(&ns->input_buffer);
 				if (!buf_push_back(&ns->input_buffer, val)) {
 					ddf_msg(LVL_WARN, "Buffer overflow on "
 					    "%s.", ns->dev->name);
+					break;
 				} else {
 					ddf_msg(LVL_DEBUG2, "Character %c saved "
 					    "to the buffer of %s.",
 					    val, ns->dev->name);
+					if (buf_was_empty)
+						fibril_condvar_broadcast(&ns->input_buffer_available);
 				}
 			}
 		}
-		
-		fibril_mutex_unlock(&ns->mutex);
-		fibril_yield();
-	}
+	}
+	fibril_mutex_unlock(&ns->mutex);
+	fibril_yield();
 }
 
 /** The interrupt handler.
  *
- * The serial port is initialized to interrupt when some data come, so the
- * interrupt is handled by reading the incomming data.
+ * The serial port is initialized to interrupt when some data come or line
+ * status register changes, so the interrupt is handled by reading the incoming
+ * data and reading the line status register.
  *
  * @param dev		The serial port device.
@@ -765,5 +782,15 @@
     ipc_call_t *icall)
 {
-	ns8250_read_from_device(NS8250_FROM_DEV(dev));
+	ns8250_t *ns = NS8250_FROM_DEV(dev);
+
+	uint8_t iir = pio_read_8(&ns->regs->iid);
+	if ((iir & NS8250_IID_CAUSE_MASK) == NS8250_IID_CAUSE_RXSTATUS) {
+		uint8_t lsr = pio_read_8(&ns->regs->lsr);
+		if (lsr & NS8250_LSR_OE) {
+			ddf_msg(LVL_WARN, "Overrun error on %s", ns->dev->name);
+		}
+	}
+	
+	ns8250_read_from_device(ns);
 }
 
@@ -811,4 +838,5 @@
 	
 	fibril_mutex_initialize(&ns->mutex);
+	fibril_condvar_initialize(&ns->input_buffer_available);
 	ns->dev = dev;
 	
@@ -1053,5 +1081,5 @@
 static void ns8250_init(void)
 {
-	ddf_log_init(NAME, LVL_ERROR);
+	ddf_log_init(NAME, LVL_WARN);
 	
 	ns8250_dev_ops.open = &ns8250_open;