root@pux:~# hdparm -d1 -c1 -k1 -X66 /dev/hda
/dev/hda:
setting 32-bit IO_support flag to 1
setting using_dma to 1 (on)
HDIO_SET_DMA failed: Operation not permitted
setting keep_settings to 1 (on)
setting xfermode to 66 (UltraDMA mode2)
IO_support = 1 (32-bit)
using_dma = 0 (off)
keepsettings = 1 (on)
root@pux:~#
Alguém sabe porquê?