How to get data from multiple datacontext (DBML) in Linq

var ObjPermission = dbOne.Permissions.ToList();

var ObjRoleMapping = (from RD in dbTwo.RoleDetails

join RM in dbTwo.RoleMasters on RD.RoleId equals RM.RoleID

                      where RM.RoleID == AgentId

                      select RD).ToList();

List<P> ObjResult = (from P in ObjPermission

join RML in ObjRoleMapping on P.PermissionID equals RML.PermissionId

              select P).ToList();