Merge of Wu's GSOC 09 branch (src.20090525.r4372.wu)

Main changes:
- COW optimization for safecopy.
- safemap, a grant-based interface for sharing memory regions between processes.
- Integration with safemap and complete rework of DS, supporting new data types
  natively (labels, memory ranges, memory mapped ranges).
- For further information:
  http://wiki.minix3.org/en/SummerOfCode2009/MemoryGrants

Additional changes not included in the original Wu's branch:
- Fixed unhandled case in VM when using COW optimization for safecopy in case
  of a block that has already been shared as SMAP.
- Better interface and naming scheme for sys_saferevmap and ds_retrieve_map
  calls.
- Better input checking in syslib: check for page alignment when creating
  memory mapping grants.
- DS notifies subscribers when an entry is deleted.
- Documented the behavior of indirect grants in case of memory mapping.
- Test suite in /usr/src/test/safeperf|safecopy|safemap|ds/* reworked
  and extended.
- Minor fixes and general cleanup.
- TO-DO: Grant ids should be generated and managed the way endpoints are to make
sure grant slots are never misreused.

kernel/proc.h

@@ -61,7 +61,7 @@ struct proc {
    * memory that isn't present, VM has to fix it. Until it has asked
    * what needs to be done and fixed it, save necessary state here.
    *
-   * The requester gets a copy of its request message in reqmsg and gets
+   * The requestor gets a copy of its request message in reqmsg and gets
    * VMREQUEST set.
    */
   struct {
@@ -70,6 +70,8 @@ struct proc {
 #define VMSTYPE_SYS_NONE	0
 #define VMSTYPE_KERNELCALL	1
 #define VMSTYPE_DELIVERMSG	2
+#define VMSTYPE_MAP		3
+
 	int		type;		/* suspended operation */
 	union {
 		/* VMSTYPE_SYS_MESSAGE */
@@ -77,10 +79,20 @@ struct proc {
 	} saved;
 
 	/* Parameters of request to VM */
-	vir_bytes 	start, length;	/* memory range */
-	u8_t		writeflag;	/* nonzero for write access */
-	endpoint_t	who;
-
+	int		req_type;
+	endpoint_t	target;
+	union {
+		struct {
+			vir_bytes 	start, length;	/* memory range */
+			u8_t		writeflag;	/* nonzero for write access */
+		} check;
+		struct {
+			char		writeflag;
+			endpoint_t	ep_s;
+			vir_bytes	vir_s, vir_d;
+			vir_bytes	length;
+		} map;
+	} params;
 	/* VM result when available */
 	int		vmresult;