The reason is that more and more libc features depend on availability of /proc. This means that you have to mount /proc within the chroot, which somewhat defeats the exercise of chrooting. On the other hand, it's not totally clear that chrooting is an effective defense anyway (I haven't got enough attack data to make a qualified judgment). So what's the response to bugs like #545808? /proc-less chroots are simply unsupported?