----------------------------USING THE GEODEAES INTERFACE----------------------------User applications can communicate with the AES engine through a series of ioctl() calls as detailed below:* ALLOCATING A SESSIONAll AES operations happen against a set session. struct geode_crypt_session {	unsigned int  flags;	unsigned int  blocksize;	unsigned char key[CRYPTO_KEY_LEN];	int id;};* Flags is a bitmask of the following options:CRYPTO_SESSION_HWKEY      Specify that the session should use the hardware key from the EEPROM.Default is offCRYPTO_SESSION_ECBIndicates that this session should use the ECB mode of encryptionCRYPTO_SESSION_CBCIndicates that this session should use the CBC mode of encryption.  Thesetwo modes cannot be defined at the same time.CRYPTO_SESSION_NOCOHERENCYIndicates that you should not use cache coherency when doing this operation.Default is to turn caching off on the pages being operated on.* Blocksize is the size of the block (from 16 to 3MB allowed)* key is an array of 16 bytes that should hold the hex equivelent of thekey (if HWKEY is set, this field is ignored).* id should be zero going in.Specify a new session by calling the ioctl:ioctl(fd, SIOCGSESSION, &session);The session id is returned in the id member.* PERFORMING AN OPERATIONTo perform a particular encryption/decryption operation, the following structure is used:struct geode_crypt_op {	int id;	unsigned int  flags;	unsigned int  len;	void *src;	void *dst;	void *iv;};* id - the session id as allocated above* flags - either CRYPTO_FLAG_DECRYPT or CRYPTO_FLAG_ENCRYPT* len - the length of the operation (not nessesarly the blocksize indicated in the session).* src,dst - the sorce and destination pointers of the data.  These must benon null and big enough to hold the block size.* iv - an optional initalization vector used in CBC mode.  If it is null,* then it is ignored.Call an operation with the following:ioctl(fd, SIOCCRYPT, &op);Any number of operations can be called on a single session.* SETTING A NEW KEY ON THE SESSIONto change the key of a session, use the following:struct geode_crypt_key {        int id;	unsigned char key[CRYPTO_KEY_LEN];};ioctl(fd, CIOSKEY, &key);* FREEING A SESSIONWhen you are done with a session, free it with followingioctl(fd, CIOFSESSION, session.id);