I've been using truecrypt for several years now. Today I upgraded to 11.10 and mounting with truecrypt failed with this message:
Error: device-mapper: reload ioctl failed: Invalid argument
On some googling I found that this could be a problem if the Kernel is not compiled with XTS support and the solution was to use "-m=nokernelcrypto" option. This works for me but this is less than ideal since there will be a performance hit.
Can anyone tell me how to get the stock 7.1 version of Truecrypt to work on Ubuntu 11.10 natively, seems like this should be a major issue if Truecrypt support was pulled from Ubuntu.