Fine grain virtualisation is pretty hackish in Linux, but it's part of the design of the Hurd. On the Hurd you can trivially virtualise the filesystem (on Linu

Fine grain virtualisation is pretty hackish in Linux, but it's part of the design of the Hurd. On the Hurd you can trivially virtualise the filesystem (on Linux you need FUSE for that but it doesn't go far enough), there are user namespaces by default (on Linux they are a hack and that makes local privilege escalation bugs really bad), drivers run in userspace, so different users can have different views on the hardware, etc. All of this is quite relevant today, especially on shared systems such as HPC clusters. The Hurd is the only multi-server micro-kernel system with a Unix persona (other micro-kernel systems are either single-server systems or don't bother with a Unix-like persona). I find it a lot more elegant than Linux, which needs to move more and more things into privileged kernel space. With the NetBSD rumpkernel the Hurd can reuse NetBSD device drivers in userspace. There are a lot of things to like about the Hurd. If only it had more contributors! It's a great project that provides practical software freedom (like other high profile GNU packages), thereby liberating users from the root user.