Towards finishing exchange_registers()

- Added mutex_trylock()
- Implemented most of exchange_registers()
- thread_control() now needs a lock for operations that can modify thread context.
- thread_start() does not initialise scheduler flags, now done in thread_create.

TODO:
- Fork/clone'ed threads should retain their context in tcb, not syscall stack.
- exchange_registers() calls in userspace need cleaning up.

include/l4/api/errno.h

@@ -144,6 +144,9 @@
 #define	EOWNERDEAD	130	/* Owner died */
 #define	ENOTRECOVERABLE	131	/* State not recoverable */
 
+/* Codezero specific error codes */
+#define EACTIVE		132	/* Task active */
+
 #ifdef __KERNEL__
 
 /* Should never be seen by user programs */

include/l4/api/exregs.h

@@ -0,0 +1,22 @@
+/*
+ * Exchange registers system call data.
+ *
+ * Copyright (C) 2008 Bahadir Balban
+ */
+#ifndef __EXREGS_H__
+#define __EXREGS_H__
+
+#include <l4/macros.h>
+#include INC_GLUE(syscall.h)
+#include INC_GLUE(context.h)
+#include <l4/types.h>
+
+/* Structure passed by userspace pagers for exchanging registers */
+struct exregs_data {
+	exregs_context_t context;
+	u32 valid_vect;
+};
+
+
+
+#endif /* __EXREGS_H__ */

include/l4/api/thread.h

@@ -1,16 +1,18 @@
 #ifndef __THREAD_H__
 #define __THREAD_H__
 
-#define THREAD_FLAGS_MASK		0x00F0
-
-/* Create new thread, copy given space */
-#define THREAD_CREATE_COPYSPC		0x0010
+#define THREAD_CREATE_MASK		0x00F0
 
 /* Create new thread and new space */
-#define THREAD_CREATE_NEWSPC		0x0020
+#define THREAD_NEW_SPACE		0x0010
+
+/* Create new thread, copy given space */
+#define THREAD_COPY_SPACE		0x0020
 
 /* Create new thread, use given space */
-#define THREAD_CREATE_SAMESPC		0x0030
+#define THREAD_SAME_SPACE		0x0030
+
+
 
 
 #define THREAD_ACTION_MASK		0x000F