playing audio CD's on modern laptops

[Hans Petter Selasky]

Hi,

On my laptop, which is not very old, they have dropped support for playing 
CD's through "cdcontrol". To play CD's one has to read the samples off the 
CD-ROM and send it to the soundcard in software. The problem is that the 
ATAPI driver complains when trying to read audio data:

acd0: WARNING - READ_CD UDMA ICRC error (retrying request)

So I tried:

sysctl hw.ata.atapi_dma=0

Which says I should put "hw.ata.atapi_dma=0" into a non-existent file. Then I 
tried:

echo hw.ata.atapi_dma="0" >> /boot/device.hints

And rebooted. Now things work.

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.

--HPS