VirtualBox: run OS X inside OS X I am using Oracle VirtualBox to run OS X inside OS X.
This entails running OS X on Mac-branded hardware so
does not break any license agreements.

I am following the instructions on this site:

http://ntk.me/2012/09/07/os-x-on-os-x/

I have downloaded "Install OS X Mavericks.app" and ran the script


  InstallESD.dmg.tool -B -i InstallESD.dmg -o Output.dmg


on the InstallESD.dmg file as advertised on the site.

This outputs a file, oddly called:

Output.dmg?.dmg

Not sure why the question mark followed by the .dmg is appended at the very end,
but anyways, I have configured VirtualBox to boot from this file, and it seems
like some progress is made, but then the kernel boot messages inside VirtualBox
seem to pause indefinitely when the following lines are reached:

init
probe
start
SMC::smcReadKeyAction ERROR OSK0 0xff(0xff) fKeyHashTable=0x0
SMC::smcReadKeyAction ERROR OSK1 0xff(0xff) fKeyHashTable=0x0
DSMOS has arrived
[IOBluetoothHCIController][start] -- completed
SMC::smcReadKeyAction ERROR BEMB 0xff(0xff) fKeyHashTable=0x0


I've been waiting 15 mnutes, the hard drive seems to be resting
with infreqeuent short flashes, and the boot process seems to
have halted at this step.

Why am I seeing this and how can I proceed with the installation
of OS X (10.9) Mavericks?

Thanks.
You will probably need to pass some boot flags to the OS while it is booting.  

I googled your error and came to this site.

His OS X booted with CPUIDMAX disabled and -x.