X-Git-Url: http://git.buserror.net/cgi-bin/gitweb.cgi?p=polintos%2Fscott%2Fpriv.git;a=blobdiff_plain;f=idl%2Faddrspace.idl;h=6b2e44b061de9ae4dce295697dad71c27fd6aced;hp=d26a681d4c39b5af70a5666f92ffddd926f4bd6b;hb=9a0f3d7f714ebabb437c30863548146b307527b7;hpb=5ee1a4b6695c7889466f97d42b8c416b080b361d

diff --git a/idl/addrspace.idl b/idl/addrspace.idl
index d26a681..6b2e44b 100644
--- a/idl/addrspace.idl
+++ b/idl/addrspace.idl
@@ -178,7 +178,25 @@ bitfield MapFlags {
 	               // then, before the write takes place, copy the object. 
 	               // It is undefined whether this mapping will receive
 	               // the copy or the original.
-	
+
+	Snapshot,      // The mapped object will also be made CopyOnWrite, so
+	               // that any writes to the mapped page via any mapping
+	               // will cause a fault.  Thus, after the snapshot, the
+	               // only changes that will be visible will be through
+	               // the new mapping.  This is ideal for things like fork()
+	               // and file versioning, and is used by AddrSpace.clone().
+	               //
+	               // If not set, then only the new mapping will be
+	               // CopyOnWrite, so if another mapping updates the page
+	               // before a write occurs through this mapping (thus
+	               // breaking CopyOnWrite), the change will be visible in
+	               // the new mapping.  This is ideal for private
+	               // mappings, where all that is desired is that the new
+	               // mapping cannot change the underlying object (while
+	               // keeping the mapping writeable).
+	               //
+	               // Ignored if CopyOnWrite is not set.
+
 	AccessFlags access:3,
 	               // These are the requested read/write/execute
 	               // permissions on the mapping.  A missing permission (or
@@ -222,11 +240,17 @@ interface AddrSpace {
 	// By default, the old address space continues to be backed by
 	// whatever Mappables were in use, and pages in the new address space
 	// are backed by anonymous memory when a page in either is written to. 
-	// If old_space_is_anon is true, though, this is reversed, which is useful
+	// If flags.Reverse is true, though, this is reversed, which is useful
 	// when versioning a file to make the new version the one that gets
 	// stored to disk.
+	//
+	// The upstream address space is also marked as copy-on
 
-	clone(AddrSpace addrspace out, bool clone_is_real);
+	clone(AddrSpace addrspace out, CloneFlags flags);
+	
+	bitfield CloneFlags {
+		Reverse
+	};
 	
 	// Mappable must be implemented by the local kernel, and must hold
 	// read/write/exec permissions appropriate for the MapFlags given.