SNAPSHOT_IOC_MAGIC
#define SNAPSHOT_FREEZE _IO(SNAPSHOT_IOC_MAGIC, 1)
#define SNAPSHOT_UNFREEZE _IO(SNAPSHOT_IOC_MAGIC, 2)
#define SNAPSHOT_ATOMIC_RESTORE _IO(SNAPSHOT_IOC_MAGIC, 4)
#define SNAPSHOT_FREE _IO(SNAPSHOT_IOC_MAGIC, 5)
#define SNAPSHOT_FREE_SWAP_PAGES _IO(SNAPSHOT_IOC_MAGIC, 9)
#define SNAPSHOT_S2RAM _IO(SNAPSHOT_IOC_MAGIC, 11)
#define SNAPSHOT_SET_SWAP_AREA _IOW(SNAPSHOT_IOC_MAGIC, 13, \
#define SNAPSHOT_GET_IMAGE_SIZE _IOR(SNAPSHOT_IOC_MAGIC, 14, __kernel_loff_t)
#define SNAPSHOT_PLATFORM_SUPPORT _IO(SNAPSHOT_IOC_MAGIC, 15)
#define SNAPSHOT_POWER_OFF _IO(SNAPSHOT_IOC_MAGIC, 16)
#define SNAPSHOT_CREATE_IMAGE _IOW(SNAPSHOT_IOC_MAGIC, 17, int)
#define SNAPSHOT_PREF_IMAGE_SIZE _IO(SNAPSHOT_IOC_MAGIC, 18)
#define SNAPSHOT_AVAIL_SWAP_SIZE _IOR(SNAPSHOT_IOC_MAGIC, 19, __kernel_loff_t)
#define SNAPSHOT_ALLOC_SWAP_PAGE _IOR(SNAPSHOT_IOC_MAGIC, 20, __kernel_loff_t)
if (_IOC_TYPE(cmd) != SNAPSHOT_IOC_MAGIC)