[1] http://news.ycombinator.com/item?id=3212515
[2] http://pdos.csail.mit.edu/6.828/2011/xv6/xv6-rev6.pdf
[1] http://pdos.csail.mit.edu/6.828/2011/xv6/book-rev6.pdf
[1] http://news.ycombinator.com/item?id=3212515
[2] http://pdos.csail.mit.edu/6.828/2011/xv6/xv6-rev6.pdf