For those who have UP boot issue with BFS, I have found that this issue was introduced between 0458 and 0460 during kernel 3.17 to 3.18. It's caused by cpu becomes idle and enter C-states.
It's not yet found why BFS UP has this issue while mainline scheduler doesn't, maybe there is some piece of codes BFS is missing during 3.17 to 3.18 migration. We still need to look into it.
Here is a workaround if you have this kind of UP booting issue. Add "idle=halt" to kernel cmdline which will disable cpu C-states when cpu is idle. Plz try this and see if it works for you.