playing audio CD's on modern laptops

Joerg Sonnenberger joerg at
Sat Jun 4 14:12:25 GMT 2005

On Sat, Jun 04, 2005 at 03:47:42PM +0200, Hans Petter Selasky wrote:
> Why is PIO mode not selected automatically by the ATAPI driver? Hence 
> obviously some manufacturers try to save money here, not supporting all modes 
> for all mediums? UDMA works for data CD-ROM's though.

(a) Because it adds a lot of overhead for normal operation e.g.
playing a DVD.
(b) Because not all drives are unable to correctly implement it,
for many ATAPI-DMA and CDDA works fine.

BTW, you can always switch without rebooting, atacontrol(8) is your friend.


More information about the freebsd-hackers mailing list