OPREGION_SIGNATURE
char buf[sizeof(OPREGION_SIGNATURE)];
if (memcmp(buf, OPREGION_SIGNATURE, 16)) {
if (memcmp(base, OPREGION_SIGNATURE, 16)) {
static_assert(sizeof(header->signature) == sizeof(OPREGION_SIGNATURE) - 1);
memcpy(header->signature, OPREGION_SIGNATURE, sizeof(header->signature));