* Added arch_debug_blue_screen_try_getchar() and arch_debug_serial_try_getchar()

which don't wait for a character, but return -1 when no character is
  available ATM. Implemented correctly for x86 only.
* Changed the semantics of the debugger_module_info::debugger_getchar() hook.
  It is supposed to return immediately now.
* Adjusted usb_keyboard accordingly. Hacked UHCI's debug_process_transfer() to
  achieve that. It does now start, check, or cancel a transfer. Split
  UHCI::ProcessDebugTransfer() into StartDebugTransfer(), and
  CheckDebugTransfer() accordingly, and also added a CancelDebugTransfer().
  The latter seems to have issues. Michael, please have a look. I have no clue
  what I'm doing. :-)
* Adjusted kgetc() to poll all possible inputs using the new
  functions/semantics. This allows to use any input (USB, PS/2, serial) in KDL.
* Removed the no longer needed "serial_input" command.
* read_line(): Also support 0x7f as backspace code. That's what xterm sends.


git-svn-id: file:///srv/svn/repos/haiku/haiku/trunk@42126 a95241bf-73f2-0310-859d-f6bbb57e9c96

headers/private/kernel/arch/debug_console.h

@@ -1,4 +1,4 @@
-/* 
+/*
  * Copyright 2002-2006, Axel Dörfler, axeld@pinc-software.de
  * Distributed under the terms of the MIT License.
  *
@@ -18,7 +18,9 @@ struct kernel_args;
 extern "C" {
 #endif
 
+int arch_debug_blue_screen_try_getchar(void);
 char arch_debug_blue_screen_getchar(void);
+int arch_debug_serial_try_getchar(void);
 char arch_debug_serial_getchar(void);
 void arch_debug_serial_putchar(char c);
 void arch_debug_serial_puts(const char *s);

src/add-ons/kernel/busses/usb/uhci.cpp

@@ -1,5 +1,5 @@
 /*
- * Copyright 2004-2006, Haiku Inc. All rights reserved.
+ * Copyright 2004-2011, Haiku Inc. All rights reserved.
  * Distributed under the terms of the MIT License.
  *
  * Authors:
@@ -23,6 +23,28 @@ static int32 sDebuggerCommandAdded = 0;
 
 
 #ifdef HAIKU_TARGET_PLATFORM_HAIKU
+
+
+class DebugTransfer : public Transfer {
+public:
+	DebugTransfer(Pipe *pipe)
+		:
+		Transfer(pipe)
+	{
+	}
+
+	uhci_td	*firstDescriptor;
+	uhci_qh	*transferQueue;
+};
+
+
+/*!	The function is an evil hack to allow <tt> <kdebug>usb_keyboard </tt> to
+	execute transfers.
+	When invoked the first time, a new transfer is started, each time the
+	function is called afterwards, it is checked whether the transfer is already
+	completed. If called with argv[1] == "cancel" the function cancels a
+	possibly pending transfer.
+*/
 static int
 debug_process_transfer(int argc, char **argv)
 {
@@ -42,9 +64,38 @@ debug_process_transfer(int argc, char **argv)
 	if (length == 0)
 		return 5;
 
-	Transfer transfer(pipe);
-	transfer.SetData(data, length);
-	return ((UHCI *)pipe->GetBusManager())->ProcessDebugTransfer(&transfer);
+	static uint8 transferBuffer[sizeof(DebugTransfer)]
+		__attribute__((aligned(16)));
+	static DebugTransfer* transfer;
+
+	UHCI *bus = (UHCI *)pipe->GetBusManager();
+
+	if (argc > 1 && strcmp(argv[1], "cancel") == 0) {
+		if (transfer != NULL) {
+			bus->CancelDebugTransfer(transfer);
+			transfer = NULL;
+		}
+		return 0;
+	}
+
+	if (transfer != NULL) {
+		bool stillPending;
+		status_t error = bus->CheckDebugTransfer(transfer, stillPending);
+		if (!stillPending)
+			transfer = NULL;
+
+		return error == B_OK ? 0 : 6;
+	}
+
+	transfer = new(transferBuffer) DebugTransfer(pipe);
+	transfer->SetData(data, length);
+
+	if (bus->StartDebugTransfer(transfer) != B_OK) {
+		transfer = NULL;
+		return 7;
+	}
+
+	return 0;
 }
 #endif
 
@@ -672,73 +723,102 @@ UHCI::SubmitTransfer(Transfer *transfer)
 
 
 status_t
-UHCI::ProcessDebugTransfer(Transfer *transfer)
+UHCI::StartDebugTransfer(DebugTransfer *transfer)
 {
-	uhci_td *firstDescriptor = NULL;
-	uhci_qh *transferQueue = NULL;
-	status_t result = CreateFilledTransfer(transfer, &firstDescriptor,
-		&transferQueue);
+	transfer->firstDescriptor = NULL;
+	transfer->transferQueue = NULL;
+	status_t result = CreateFilledTransfer(transfer, &transfer->firstDescriptor,
+		&transfer->transferQueue);
 	if (result < B_OK)
 		return result;
 
-	fQueues[UHCI_DEBUG_QUEUE]->AppendTransfer(transferQueue, false);
+	fQueues[UHCI_DEBUG_QUEUE]->AppendTransfer(transfer->transferQueue, false);
 
-	while (true) {
-		bool transferOK = false;
-		bool transferError = false;
-		uhci_td *descriptor = firstDescriptor;
+	return B_OK;
+}
 
-		while (descriptor) {
-			uint32 status = descriptor->status;
-			if (status & TD_STATUS_ACTIVE)
-				break;
 
-			if (status & TD_ERROR_MASK) {
-				transferError = true;
-				break;
-			}
+status_t
+UHCI::CheckDebugTransfer(DebugTransfer *transfer, bool &_stillPending)
+{
+	bool transferOK = false;
+	bool transferError = false;
+	uhci_td *descriptor = transfer->firstDescriptor;
 
-			if ((descriptor->link_phy & TD_TERMINATE)
-				|| uhci_td_actual_length(descriptor)
-					< uhci_td_maximum_length(descriptor)) {
-				transferOK = true;
-				break;
-			}
+	while (descriptor) {
+		uint32 status = descriptor->status;
+		if (status & TD_STATUS_ACTIVE)
+			break;
 
-			descriptor = (uhci_td *)descriptor->link_log;
+		if (status & TD_ERROR_MASK) {
+			transferError = true;
+			break;
 		}
 
-		if (!transferOK && !transferError) {
-			spin(200);
-			continue;
+		if ((descriptor->link_phy & TD_TERMINATE)
+			|| uhci_td_actual_length(descriptor)
+				< uhci_td_maximum_length(descriptor)) {
+			transferOK = true;
+			break;
 		}
 
-		if (transferOK) {
-			size_t actualLength = 0;
-			uint8 lastDataToggle = 0;
-			if (transfer->TransferPipe()->Direction() == Pipe::In) {
-				// data to read out
-				iovec *vector = transfer->Vector();
-				size_t vectorCount = transfer->VectorCount();
-
-				actualLength = ReadDescriptorChain(firstDescriptor,
-					vector, vectorCount, &lastDataToggle);
-			} else {
-				// read the actual length that was sent
-				actualLength = ReadActualLength(firstDescriptor,
-					&lastDataToggle);
-			}
-
-			transfer->TransferPipe()->SetDataToggle(lastDataToggle == 0);
-		}
-
-		fQueues[UHCI_DEBUG_QUEUE]->RemoveTransfer(transferQueue, false);
-		FreeDescriptorChain(firstDescriptor);
-		FreeTransferQueue(transferQueue);
-		return transferOK ? B_OK : B_IO_ERROR;
+		descriptor = (uhci_td *)descriptor->link_log;
 	}
 
-	return B_ERROR;
+	if (!transferOK && !transferError) {
+		spin(200);
+		_stillPending = true;
+		return B_OK;
+	}
+
+	if (transferOK) {
+		size_t actualLength = 0;
+		uint8 lastDataToggle = 0;
+		if (transfer->TransferPipe()->Direction() == Pipe::In) {
+			// data to read out
+			iovec *vector = transfer->Vector();
+			size_t vectorCount = transfer->VectorCount();
+
+			actualLength = ReadDescriptorChain(transfer->firstDescriptor,
+				vector, vectorCount, &lastDataToggle);
+		} else {
+			// read the actual length that was sent
+			actualLength = ReadActualLength(transfer->firstDescriptor,
+				&lastDataToggle);
+		}
+
+		transfer->TransferPipe()->SetDataToggle(lastDataToggle == 0);
+	}
+
+	fQueues[UHCI_DEBUG_QUEUE]->RemoveTransfer(transfer->transferQueue, false);
+	FreeDescriptorChain(transfer->firstDescriptor);
+	FreeTransferQueue(transfer->transferQueue);
+	_stillPending = false;
+	return transferOK ? B_OK : B_IO_ERROR;
+}
+
+
+void
+UHCI::CancelDebugTransfer(DebugTransfer *transfer)
+{
+	// clear the active bit so the descriptors are canceled
+	uhci_td *descriptor = transfer->firstDescriptor;
+	while (descriptor) {
+		descriptor->status &= ~TD_STATUS_ACTIVE;
+		descriptor = (uhci_td *)descriptor->link_log;
+	}
+
+	transfer->Finished(B_CANCELED, 0);
+
+	// dequeue and free resources
+	fQueues[UHCI_DEBUG_QUEUE]->RemoveTransfer(transfer->transferQueue, false);
+	FreeDescriptorChain(transfer->firstDescriptor);
+	FreeTransferQueue(transfer->transferQueue);
+	// TODO: [bonefish] The Free*() calls cause "PMA: provided address resulted
+	// in invalid index" to be printed, so apparently something is not right.
+	// Though I have not clue what. This is the same cleanup code as in
+	// CheckDebugTransfer() that should undo the CreateFilledTransfer() from
+	// StartDebugTransfer().
 }
 
 
@@ -1832,7 +1912,7 @@ status_t
 UHCI::AddTo(Stack *stack)
 {
 #ifdef TRACE_USB
-	set_dprintf_enabled(true); 
+	set_dprintf_enabled(true);
 #ifndef HAIKU_TARGET_PLATFORM_HAIKU
 	load_driver_symbols("uhci");
 #endif

src/add-ons/kernel/busses/usb/uhci.h

@@ -1,5 +1,5 @@
 /*
- * Copyright 2004-2006, Haiku Inc. All rights reserved.
+ * Copyright 2004-2011, Haiku Inc. All rights reserved.
  * Distributed under the terms of the MIT License.
  *
  * Authors:
@@ -24,6 +24,7 @@
 struct pci_info;
 struct pci_module_info;
 class UHCIRootHub;
+class DebugTransfer;
 
 
 class Queue {
@@ -97,7 +98,11 @@ public:
 
 		status_t					Start();
 virtual	status_t					SubmitTransfer(Transfer *transfer);
-		status_t					ProcessDebugTransfer(Transfer *transfer);
+		status_t					StartDebugTransfer(DebugTransfer *transfer);
+		status_t					CheckDebugTransfer(DebugTransfer *transfer,
+										bool &_stillPending);
+		void						CancelDebugTransfer(
+										DebugTransfer *transfer);
 virtual	status_t					CancelQueuedTransfers(Pipe *pipe, bool force);
 		status_t					CancelQueuedIsochronousTransfers(Pipe *pipe, bool force);
 		status_t					SubmitRequest(Transfer *transfer);

src/add-ons/kernel/debugger/usb_keyboard/usb_keyboard.cpp

@@ -1,5 +1,5 @@
 /*
- * Copyright 2009, Haiku Inc. All rights reserved.
+ * Copyright 2009-2011, Haiku, Inc. All rights reserved.
  * Distributed under the terms of the MIT License.
  *
  * Authors:
@@ -176,6 +176,9 @@ enter_debugger(void)
 static void
 exit_debugger(void)
 {
+	// make sure a possibly pending transfer is canceled
+	evaluate_debug_command("uhci_process_transfer cancel");
+
 	sUseUSBKeyboard = false;
 }
 
@@ -195,11 +198,12 @@ debugger_getchar(void)
 	if (!sUseUSBKeyboard)
 		return -1;
 
-	while (sBufferedCharCount == 0) {
+	if (sBufferedCharCount == 0) {
 		set_debug_variable("_usbPipe", (uint64)sUSBPipe);
 		set_debug_variable("_usbTransferData", (uint64)sUSBTransferData);
 		set_debug_variable("_usbTransferLength", (uint64)sUSBTransferLength);
-		evaluate_debug_command("uhci_process_transfer");
+		if (evaluate_debug_command("uhci_process_transfer") != 0)
+			return -1;
 
 		bool phantomState = true;
 		for (size_t i = 2; i < sUSBTransferLength; i++) {
@@ -210,7 +214,7 @@ debugger_getchar(void)
 		}
 
 		if (phantomState)
-			continue;
+			return -1;
 
 		uint8 modifiers = 0;
 		for (uint32 i = 0; i < 8; i++) {
@@ -272,6 +276,9 @@ debugger_getchar(void)
 			sLastTransferData[i] = sUSBTransferData[i];
 	}
 
+	if (sBufferedCharCount == 0)
+		return -1;
+
 	int result = sBufferedChars[sBufferReadIndex++];
 	sBufferReadIndex %= sBufferSize;
 	sBufferedCharCount--;
@@ -302,7 +309,7 @@ static struct debugger_module_info sModuleInfo = {
 	&debugger_getchar
 };
 
-module_info *modules[] = { 
+module_info *modules[] = {
 	(module_info *)&sModuleInfo,
 	NULL
 };

src/system/kernel/arch/arm/arch_debug_console.cpp

@@ -31,6 +31,14 @@ arch_debug_install_interrupt_handlers(void)
 }
 
 
+int
+arch_debug_blue_screen_try_getchar(void)
+{
+	// TODO: Implement correctly!
+	return arch_debug_blue_screen_getchar();
+}
+
+
 char
 arch_debug_blue_screen_getchar(void)
 {
@@ -38,6 +46,14 @@ arch_debug_blue_screen_getchar(void)
 }
 
 
+int
+arch_debug_serial_try_getchar(void)
+{
+	// TODO: Implement correctly!
+	return arch_debug_serial_getchar();
+}
+
+
 char
 arch_debug_serial_getchar(void)
 {

src/system/kernel/arch/m68k/arch_debug_console.cpp

@@ -31,6 +31,14 @@ arch_debug_install_interrupt_handlers(void)
 }
 
 
+int
+arch_debug_blue_screen_try_getchar(void)
+{
+	// TODO: Implement correctly!
+	return arch_debug_blue_screen_getchar();
+}
+
+
 char
 arch_debug_blue_screen_getchar(void)
 {
@@ -38,6 +46,14 @@ arch_debug_blue_screen_getchar(void)
 }
 
 
+int
+arch_debug_serial_try_getchar(void)
+{
+	// TODO: Implement correctly!
+	return arch_debug_serial_getchar();
+}
+
+
 char
 arch_debug_serial_getchar(void)
 {

src/system/kernel/arch/mipsel/arch_debug_console.cpp

@@ -31,6 +31,14 @@ arch_debug_install_interrupt_handlers(void)
 }
 
 
+int
+arch_debug_blue_screen_try_getchar(void)
+{
+#warning IMPLEMENT arch_debug_blue_screen_try_getchar
+	return -1;
+}
+
+
 char
 arch_debug_blue_screen_getchar(void)
 {
@@ -39,6 +47,14 @@ arch_debug_blue_screen_getchar(void)
 }
 
 
+int
+arch_debug_serial_try_getchar(void)
+{
+#warning IMPLEMENT arch_debug_serial_try_getchar
+	return -1;
+}
+
+
 char
 arch_debug_serial_getchar(void)
 {

src/system/kernel/arch/ppc/arch_debug_console.cpp

@@ -28,6 +28,14 @@ arch_debug_install_interrupt_handlers(void)
 }
 
 
+int
+arch_debug_blue_screen_try_getchar(void)
+{
+	// TODO: Implement correctly!
+	return arch_debug_blue_screen_getchar();
+}
+
+
 char
 arch_debug_blue_screen_getchar(void)
 {
@@ -35,6 +43,14 @@ arch_debug_blue_screen_getchar(void)
 }
 
 
+int
+arch_debug_serial_try_getchar(void)
+{
+	// TODO: Implement correctly!
+	return arch_debug_serial_getchar();
+}
+
+
 char
 arch_debug_serial_getchar(void)
 {

src/system/kernel/arch/x86/arch_debug_console.cpp

@@ -166,8 +166,8 @@ arch_debug_install_interrupt_handlers(void)
 }
 
 
-char
-arch_debug_blue_screen_getchar(void)
+int
+arch_debug_blue_screen_try_getchar(void)
 {
 	/* polling the keyboard, similar to code in keyboard
 	 * driver, but without using an interrupt
@@ -194,105 +194,126 @@ arch_debug_blue_screen_getchar(void)
 		return key;
 	}
 
-	while (true) {
-		uint8 status = in8(PS2_PORT_CTRL);
+	uint8 status = in8(PS2_PORT_CTRL);
 
-		if ((status & PS2_STATUS_OUTPUT_BUFFER_FULL) == 0) {
-			// no data in keyboard buffer
-			spin(200);
-			continue;
+	if ((status & PS2_STATUS_OUTPUT_BUFFER_FULL) == 0) {
+		// no data in keyboard buffer
+		return -1;
+	}
+
+	key = in8(PS2_PORT_DATA);
+
+	if (status & PS2_STATUS_AUX_DATA) {
+		// we read mouse data, ignore it
+		return -1;
+	}
+
+	if (key & 0x80) {
+		// key up
+		switch (key & ~0x80) {
+			case LEFT_SHIFT:
+			case RIGHT_SHIFT:
+				shiftPressed = false;
+				return -1;
+			case LEFT_CONTROL:
+				controlPressed = false;
+				return -1;
+			case LEFT_ALT:
+				altPressed = false;
+				return -1;
 		}
+	} else {
+		// key down
+		switch (key) {
+			case LEFT_SHIFT:
+			case RIGHT_SHIFT:
+				shiftPressed = true;
+				return -1;
 
-		spin(200);
-		key = in8(PS2_PORT_DATA);
+			case LEFT_CONTROL:
+				controlPressed = true;
+				return -1;
 
-		if (status & PS2_STATUS_AUX_DATA) {
-			// we read mouse data, ignore it
-			continue;
-		}
+			case LEFT_ALT:
+				altPressed = true;
+				return -1;
 
-		if (key & 0x80) {
-			// key up
-			switch (key & ~0x80) {
-				case LEFT_SHIFT:
-				case RIGHT_SHIFT:
-					shiftPressed = false;
-					break;
-				case LEFT_CONTROL:
-					controlPressed = false;
-					break;
-				case LEFT_ALT:
-					altPressed = false;
-					break;
-			}
-		} else {
-			// key down
-			switch (key) {
-				case LEFT_SHIFT:
-				case RIGHT_SHIFT:
-					shiftPressed = true;
-					break;
-
-				case LEFT_CONTROL:
-					controlPressed = true;
-					break;
-
-				case LEFT_ALT:
-					altPressed = true;
-					break;
-
-				// start escape sequence for cursor movement
-				case CURSOR_UP:
-					special = 0x80 | 'A';
-					return '\x1b';
-				case CURSOR_DOWN:
-					special = 0x80 | 'B';
-					return '\x1b';
-				case CURSOR_RIGHT:
-					special = 0x80 | 'C';
-					return '\x1b';
-				case CURSOR_LEFT:
-					special = 0x80 | 'D';
-					return '\x1b';
-				case CURSOR_HOME:
-					special = 0x80 | 'H';
-					return '\x1b';
-				case CURSOR_END:
-					special = 0x80 | 'F';
-					return '\x1b';
-				case PAGE_UP:
-					special = 0x80 | '5';
-					special2 = '~';
-					return '\x1b';
-				case PAGE_DOWN:
-					special = 0x80 | '6';
-					special2 = '~';
-					return '\x1b';
+			// start escape sequence for cursor movement
+			case CURSOR_UP:
+				special = 0x80 | 'A';
+				return '\x1b';
+			case CURSOR_DOWN:
+				special = 0x80 | 'B';
+				return '\x1b';
+			case CURSOR_RIGHT:
+				special = 0x80 | 'C';
+				return '\x1b';
+			case CURSOR_LEFT:
+				special = 0x80 | 'D';
+				return '\x1b';
+			case CURSOR_HOME:
+				special = 0x80 | 'H';
+				return '\x1b';
+			case CURSOR_END:
+				special = 0x80 | 'F';
+				return '\x1b';
+			case PAGE_UP:
+				special = 0x80 | '5';
+				special2 = '~';
+				return '\x1b';
+			case PAGE_DOWN:
+				special = 0x80 | '6';
+				special2 = '~';
+				return '\x1b';
 
 
-				case DELETE:
-					if (controlPressed && altPressed)
-						arch_cpu_shutdown(true);
+			case DELETE:
+				if (controlPressed && altPressed)
+					arch_cpu_shutdown(true);
 
-					special = 0x80 | '3';
-					special2 = '~';
-					return '\x1b';
+				special = 0x80 | '3';
+				special2 = '~';
+				return '\x1b';
 
-				default:
-					if (controlPressed) {
-						char c = kShiftedKeymap[key];
-						if (c >= 'A' && c <= 'Z')
-							return 0x1f & c;
-					}
+			default:
+				if (controlPressed) {
+					char c = kShiftedKeymap[key];
+					if (c >= 'A' && c <= 'Z')
+						return 0x1f & c;
+				}
 
-					if (altPressed)
-						return kAltedKeymap[key];
+				if (altPressed)
+					return kAltedKeymap[key];
 
-					return shiftPressed
-						? kShiftedKeymap[key] : kUnshiftedKeymap[key];
-			}
+				return shiftPressed
+					? kShiftedKeymap[key] : kUnshiftedKeymap[key];
 		}
 	}
+
+	return -1;
+}
+
+
+char
+arch_debug_blue_screen_getchar(void)
+{
+	while (true) {
+		int c = arch_debug_blue_screen_try_getchar();
+		if (c >= 0)
+			return (char)c;
+
+		PAUSE();
+	}
+}
+
+
+int
+arch_debug_serial_try_getchar(void)
+{
+	if ((in8(sSerialBasePort + SERIAL_LINE_STATUS) & 0x1) == 0)
+		return -1;
+
+	return in8(sSerialBasePort + SERIAL_RECEIVE_BUFFER);
 }
 
 

src/system/kernel/debug/blue_screen.cpp

@@ -659,6 +659,13 @@ blue_screen_clear_screen(void)
 }
 
 
+int
+blue_screen_try_getchar(void)
+{
+	return arch_debug_blue_screen_try_getchar();
+}
+
+
 char
 blue_screen_getchar(void)
 {

src/system/kernel/debug/blue_screen.h

@@ -20,6 +20,7 @@ bool blue_screen_paging_enabled(void);
 void blue_screen_set_paging(bool enabled);
 
 void blue_screen_clear_screen(void);
+int blue_screen_try_getchar(void);
 char blue_screen_getchar(void);
 void blue_screen_putchar(char c);
 void blue_screen_puts(const char *text);

src/system/kernel/debug/debug.cpp

@@ -90,7 +90,6 @@ static bool sSyslogOutputEnabled = true;
 static bool sBlueScreenEnabled = false;
 	// must always be false on startup
 static bool sDebugScreenEnabled = false;
-static bool sSerialInputEnabled = false;
 static bool sBlueScreenOutput = true;
 static bool sEmergencyKeysEnabled = true;
 static spinlock sSpinlock = B_SPINLOCK_INITIALIZER;
@@ -474,7 +473,8 @@ read_line(char* buffer, int32 maxLength,
 				}
 				break;
 			}
-			case 8: // backspace
+			case 8:		// backspace (CTRL-H)
+			case 0x7f:	// backspace (xterm)
 				if (position > 0) {
 					kputs("\x1b[1D"); // move to the left one
 					position--;
@@ -681,22 +681,30 @@ read_line(char* buffer, int32 maxLength,
 char
 kgetc(void)
 {
-	if (sSerialInputEnabled)
-		return arch_debug_serial_getchar();
+	while (true) {
+		// check serial input
+		int c = arch_debug_serial_try_getchar();
+		if (c >= 0)
+			return (char)c;
 
-	// give the kernel debugger modules a chance first
-	for (uint32 i = 0; i < kMaxDebuggerModules; i++) {
-		if (sDebuggerModules[i] && sDebuggerModules[i]->debugger_getchar) {
-			int getChar = sDebuggerModules[i]->debugger_getchar();
-			if (getChar >= 0)
-				return (char)getChar;
+		// check blue screen input
+		if (sBlueScreenOutput) {
+			c = blue_screen_try_getchar();
+			if (c >= 0)
+				return (char)c;
 		}
+
+		// give the kernel debugger modules a chance
+		for (uint32 i = 0; i < kMaxDebuggerModules; i++) {
+			if (sDebuggerModules[i] && sDebuggerModules[i]->debugger_getchar) {
+				int getChar = sDebuggerModules[i]->debugger_getchar();
+				if (getChar >= 0)
+					return (char)getChar;
+			}
+		}
+
+		PAUSE();
 	}
-
-	if (sBlueScreenOutput)
-		return blue_screen_getchar();
-
-	return arch_debug_serial_getchar();
 }
 
 
@@ -1136,16 +1144,6 @@ cmd_dump_syslog(int argc, char** argv)
 }
 
 
-static int
-cmd_serial_input(int argc, char** argv)
-{
-	sSerialInputEnabled = !sSerialInputEnabled;
-	kprintf("Serial input is turned %s now.\n",
-		sSerialInputEnabled ? "on" : "off");
-	return 0;
-}
-
-
 static int
 cmd_switch_cpu(int argc, char** argv)
 {
@@ -1413,9 +1411,6 @@ syslog_init_post_vm(struct kernel_args* args)
 		"Dumps the whole syslog buffer, or, if -k is specified, only "
 		"the part that hasn't been sent yet.\n", 0);
 
-	add_debugger_command("serial_input", &cmd_serial_input,
-		"Enable or disable serial input");
-
 	return B_OK;
 
 err2: