draft: current implementation

map.go

@@ -351,7 +351,34 @@ func (spec *MapSpec) createMap(inner *sys.FD, opts MapOptions) (_ *Map, err erro
 	}
 
 	switch spec.Type {
-	case ArrayOfMaps, HashOfMaps:
+	case LRUHash:
+		if spec.Flags&unix.BPF_F_NO_PREALLOC > 0 {
+			return nil, errors.New("no prealloc flag cannot be set for lru hash")
+		}
+	case RingBuf:
+		if spec.Flags&unix.BPF_F_NO_PREALLOC > 0 {
+			return nil, errors.New("no prealloc flag cannot be set for ring buf")
+		}
+	case PerCPUArray:
+		if spec.Flags&unix.BPF_F_NO_PREALLOC > 0 {
+			return nil, errors.New("no prealloc flag cannot be set for per cpu array")
+		}
+	case ArrayOfMaps:
+		if spec.Flags&unix.BPF_F_NO_PREALLOC > 0 {
+			return nil, errors.New("no prealloc flag cannot be set for array of maps")
+		}
+		if err := haveNestedMaps(); err != nil {
+			return nil, err
+		}
+
+		if spec.ValueSize != 0 && spec.ValueSize != 4 {
+			return nil, errors.New("ValueSize must be zero or four for map of map")
+		}
+
+		spec = spec.Copy()
+		spec.ValueSize = 4
+
+	case HashOfMaps:
 		if err := haveNestedMaps(); err != nil {
 			return nil, err
 		}