Convenient way to enable IDE DMA

[Nate Eldredge <nate@cs.hmc.edu>]

I just noticed that IDE DMA is not enabled by default in woody, nor in the
kernel-image package (at least for 2.4.18 and I assume for the others
also).  I can understand this, since there are some systems for which
enabling IDE results in hideous corruption.  But for others it gives you a
a huge increase in disk performance (about a factor of 10 in my hdparm -t
tests).  So I think there should be a convenient and well-documented way
to enable it.  Perhaps a configuration option should be offered.

The other question is how it should be enabled.  One way is "hdparm -d 1
/dev/hd?" or moral equivalent in an init script.  Another way appears to
be "hda=dma ..." or "ide0=dma ..." on the kernel command line, though I
haven't tested this yet.  Apparently there are also CD-ROM drives for
which it should not be enabled.

I think this is important.  DMA disabled has given me trouble with CD
burning and video capture, and you should not have to be an expert to be
able to turn it on.  (I consider that expecting newbies to write an init
script or look up kernel command line options is not really reasonable.)
Also, it may give people the impression that Debian is "slow".

Thoughts?

-- 
Nate Eldredge
HMC CS Staff
nate@cs.hmc.edu