I have upgraded from 2.4.19 to 2.4.22-r4 on one machine and 2.6.1 on another.
In both cases hdparm returns this:
HDIO_SET_DMA failed: Operation not permitted
The best would be to compare chipset related options between your old (working) and actual .config files.
Let me guess, u used genkernel !? If yes, it's expected "feature" :-).
noro
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