> Both have several escape-hatches for arbitrary driver-userspace communication, which makes the number of syscalls pretty irrelevant. (E.g. Linux has ioctl, ne

> Both have several escape-hatches for arbitrary driver-userspace communication, which makes the number of syscalls pretty irrelevant. (E.g. Linux has ioctl, netlink, procfs, sysfs, ...) Yes, we need a better metric for accounting for those things, which will paint a much more sobering picture of the complexity and growth of complexity of the userland <-> kernel interface.