[boost] [context][fiber] context migration

Hi, I have a question about context; basically it seems that all the yield functionality can be done by simply calling jump_to on the calling context. is that right? I've also been trying to figure out exactly what functionality does fiber implements on top of it; it seems that fiber migration (to another kernel thread? another process?) is implemented (or eventually will be implemented) here? thanks for any lights on this, Charles J. Quarra