[root@fette]~ #mount -t tmpfs none /root/tmpfs -o size=130m
[root@fette]~ #dd if=/dev/zero of=/root/tmpfs/test.img count=131072 bs=1024
131072+0 records in
131072+0 records out
134217728 bytes (134 MB) copied, 2,12168 s, 63,3 MB/s
[root@fette]~ #losetup /dev/loop1 /root/tmpfs/test.img
[root@fette]~ #rmmod geode_aes
[root@fette]~ #cryptsetup -y --cipher aes --key-size 128 luksFormat /dev/loop1

WARNING!
========
This will overwrite data on /dev/loop1 irrevocably.

Are you sure? (Type uppercase yes): YES
Enter LUKS passphrase:
Verify passphrase:
Command successful.
[root@fette]~ #cryptsetup luksOpen /dev/loop1 test
Enter LUKS passphrase:
key slot 0 unlocked.
Command successful.
[root@fette]~ #dd if=/dev/zero of=/dev/mapper/test bs=16384
dd: writing `/dev/mapper/test': No space left on device
8160+0 records in
8159+0 records out
133689344 bytes (134 MB) copied, 24,7012 s, 5,4 MB/s
[root@fette]~ #cryptsetup luksClose test
[root@fette]~ #modprobe geode_aes
[root@fette]~ #cryptsetup luksOpen /dev/loop1 test
Enter LUKS passphrase:
key slot 0 unlocked.
Command successful.
[root@fette]~ #dd if=/dev/zero of=/dev/mapper/test bs=16384
dd: writing `/dev/mapper/test': No space left on device
8160+0 records in
8159+0 records out
133689344 bytes (134 MB) copied, 24,4097 s, 5,5 MB/s
[root@fette]~ #lsmod |grep aes
geode_aes               7176  1 
aes_i586               33536  0 
blkcipher               8324  2 geode_aes,cbc

[root@fette]~ #cryptsetup luksClose test
[root@fette]~ #cryptsetup -y --cipher aes-cbc-essiv:sha256 --key-size 128 luksFormat /dev/loop1

WARNING!
========
This will overwrite data on /dev/loop1 irrevocably.

Are you sure? (Type uppercase yes): YES
Enter LUKS passphrase:
Verify passphrase:
Failed to setup dm-crypt key mapping.
Check kernel for support for the aes-cbc-essiv:sha256 cipher spec and verify that /dev/loop1 contains at least 133 sectors.
Failed to write to key storage.
Command failed.