mkreiserfs block size limit other than in man / info page?

I have tried to format a partition on an USB pendrive with mkreiserfs 3.6.21 as follows: mkreiserfs --block-size=2048 /dev/sdb1 Which resulted in > Block sizes smaller than 4k are not supported. Interesting, because both info and man mkreiserfs describe as possible block size: > -b | --block-size N
N is block size in bytes. It may only be set to a power of 2 within the 512-8192 interval. So I tried it from the other end: > mkreiserfs /dev/sdb1 --block-size=8192 and got: Block sizes larger than 4k are not supported on all architectures. A bit picky, aren't we… Working with Linux 3.2.0-4-amd64 kernel I've tried the same as before in combination with the --format option. Same results. Question -------- *What am I doing wrong?* Some ideas I came across: - bad idea to create this on an USB device - *problem is located in the compiled version of mkreiserfs?* - (*bug in documentation*?) Yes, I know that reiser4 was created to replace reiserfs and it isn't very common anymore (or could I say "*is defunct*"?). ---------- Having little to no idea about .h files but at least willing to try to find anything informative, I found this in /usr/include/linux/reiserfs_fs.h - not helpful but worth sharing, I guess: