1#val_type uint64_t
2UFFD_FEATURE_PAGEFAULT_FLAG_WP
3UFFD_FEATURE_EVENT_FORK
4UFFD_FEATURE_EVENT_REMAP
5UFFD_FEATURE_EVENT_REMOVE
6UFFD_FEATURE_MISSING_HUGETLBFS
7UFFD_FEATURE_MISSING_SHMEM
8UFFD_FEATURE_EVENT_UNMAP
9UFFD_FEATURE_SIGBUS
10UFFD_FEATURE_THREAD_ID
11