[oe] sysvinit runlevels

[E Robertson]

Hi,
I'm building a busybox based distro using busybox init. I notice sysvinit run 
levels unexpectedly showed up my rootfs. Is this normally what it does and I 
need to explicitly remove them? 
Also, I couldn't find the "?=" operation in the bitbake manual so I assumed it 
a condition statement and is overridden of the variable is defined, it this 
true?
Thanks.