* Added support for debugger handover.

* Implemented _user_wait_for_debugger().
* Reworked a few bits to ensure that after a remove_team_debugger() or
  after requesting a debugger handover the debugger doesn't get any more
  messages.
* When the debugger is removed or dies, the debugged threads should now
  cleanup their debug info and continue, instead of waiting at their
  debug port forever.
All the new features are not tested. Will happen, when gdb will be
debugged.


git-svn-id: file:///srv/svn/repos/haiku/trunk/current@11664 a95241bf-73f2-0310-859d-f6bbb57e9c96

headers/private/kernel/user_debugger.h

@@ -40,6 +40,9 @@ struct team_debug_info {
 	thread_id	nub_thread;
 	port_id		nub_port;
 		// the port the nub thread is waiting on for commands from the debugger
+	sem_id		debugger_write_lock;
+		// synchronizes writes to the debugger port with the setting (but not
+		// clearing) of the B_TEAM_DEBUG_DEBUGGER_HANDOVER flag
 
 	struct arch_team_debug_info	arch_info;
 };
@@ -61,6 +64,7 @@ struct thread_debug_info {
 // team debugging flags (user-specifiable flags are in <debugger.h>)
 enum {
 	B_TEAM_DEBUG_DEBUGGER_INSTALLED	= 0x0001,
+	B_TEAM_DEBUG_DEBUGGER_HANDOVER	= 0x0002,
 
 	B_TEAM_DEBUG_KERNEL_FLAG_MASK	= 0xffff,
 
@@ -87,6 +91,7 @@ typedef enum {
 	B_DEBUGGED_THREAD_MESSAGE_CONTINUE	= 0,
 	B_DEBUGGED_THREAD_GET_WHY_STOPPED,
 	B_DEBUGGED_THREAD_SET_CPU_STATE,
+	B_DEBUGGED_THREAD_DEBUGGER_CHANGED,
 } debugged_thread_message;
 
 typedef struct {
@@ -109,6 +114,12 @@ typedef union {
 } debugged_thread_message_data;
 
 
+// internal messages sent to the nub thread
+typedef enum {
+	B_DEBUG_MESSAGE_HANDED_OVER		= -1,
+} debug_nub_kernel_message;
+
+
 #ifdef __cplusplus
 extern "C" {
 #endif