MAP_CONCEAL
#if defined(MAP_CONCEAL)
# define PREKEY_MMAP_FLAG MAP_CONCEAL
#if defined(MADV_DONTDUMP) && !defined(MAP_CONCEAL) && !defined(MAP_NOCORE)
PROT_READ | PROT_WRITE, MAP_ANON | MAP_PRIVATE | MAP_CONCEAL, -1, 0);
#if !defined(MAP_CONCEAL)