Highlights of Linux kernel 5.1 include the ability to use persistent memory as RAM (system memory) in addition to the physical RAM, more preparations for year 2038, the ability to boot the system to a device-mapper device without using initramfs, as well as support for cumulative patches for the live kernel patching feature. For fans of the Btrfs file system, the Linux 5.1 kernel series finally allows users to configure Zstd compression levels. In addition, the fanotify-based file system monitorization feature was improved by adding a so-called “super block root watch” functionality to the fanotify interface, which scalably watches changes on large filesystems.