I'm making progress with my XO. From the commandline, I've got realtime MIDI 
working with one of my .csd's.

My problem: though everything seems to work, audio breakup is terrible (it 
is systemic; rhythmic dropouts at the rate of 5 or so per second).

I've used both of the following sets of :

-odac -+rtmidi=alsa -M 
hw:1,0 -m0d --expression-opt -b2048 -B4096 -+raw_controller_mode=1

-+rtaudio=alsa -odac -+rtmidi=alsa -M 
hw:1,0 -m0d --expression-opt -b2048 -B4096 -+raw_controller_mode=1

With lower values for -b and -B (my usual set for the PC), if anything, 
breakup is worse.

I tried disconnecting my internet connection; no difference.

The .csd runs with <20% usage on my current PC; unless internet is 
connected, it runs with zero breakup (i.e., flawlessly). My .csd consists of 
16 always-on voices (all the same - not overly complex).

If there is no good solution for this situation, my OLPC projects are dead 
in the water.

I'd appreciate suggestions.

And BTW, I join with others in wishing a blessed holiday season to all.

Art Hunkins