cd(4) as compared to acd(4)

[Andriy Gapon]

It seems that cd driver lacks couple of useful features as compared to acd:
1. device nodes for individual tracks: this might not be so useful for
tracks on audio CDs, but it is especially useful for mixed audio/data
CDs and multi-track data CDs;
2. automatic detection of track type (audio/data) and then using proper
READ command (e.g. READ CD) in strategy, so that read(2) works even for
audio CDs (convenient and easy way of doing digital audio extraction);

The second one also breaks "API" compatibility between the drivers: if
you want to do digital audio extraction, you have to know underlying
device type and use different techniques.

It seems that these features are not terribly hard to implement (using
acd as an example). I am not volunteering at this moment, but this could
be added to some "junior hacker tasks" list.

-- 
Andriy Gapon