CheriBSD

CheriBSD 22.12 Release Notes

Overview

Welcome to the Fall 2022 (22.12) release of the CheriBSD operating system. As well as a general update of the baseline FreeBSD OS from which CheriBSD is derived, we have introduced several new research components which will be of interest to the CHERI and CheriBSD community:

  • Memory-safe adaptation of Direct Rendering Manager (DRM) and Panfrost device driver, which enable a Morello-based desktop system using on-board GPU and HDMI. These drivers may be used with hybrid or pure-capability kernels.
  • An initial set of graphics and desktop CheriABI software packages such as Wayland and portions of KDE to get you up and running with a memory-safe desktop environment. These components remain under active development, and we anticipate continuing package updates after the CheriBSD release.
  • An early research prototype of Library Compartmentalization (https://github.com/CTSRD-CHERI/cheripedia/wiki/Library-based-Compartmentalisation), which implements an alternative run-time linker running shared objects in libraries. This implementation is very much a work-in-progress, and is provided to enable research at other collaborator institutions needing easy access to the prototype. It is neither complete nor intended to be secure.
  • Improved pluggability of experimental heap temporal memory-safety support, which is not yet merged into the main development branch, but will now be easier to use by downloading an alternative kernel and heap allocator libraries provided by Microsoft.
  • Support for a newer version of GDB in CheriBSD, which provides generally improved debugging support including Morello code disassembly and hardware watchpoints. We have also added support for memory tag access from the debugger on live targets as well as core dumps.
  • Alpha support for ZFS file systems including support for boot environments.

While CheriBSD is by definition an experimental research operating system, the above features – other than GDB improvements – are not yet considered to be mature. They are being made available as an early release to facilitate collaboration, but will not be suitable for a general Morello audience until the following release.

As with previous releases, the default CheriBSD kernel on Morello ships with debugging features enabled, which should be disabled by booting a non-debug kernel before any performance benchmarking is performed.

Known Issues

  • If a USB hub is plugged in (including embedded hubs in USB keyboards) the system will pause on boot due to a firmware bug. Some people find they can bypass this pause by pressing Enter on a USB keyboard attached to the Morello desktop system. Others find they must unplug the hub to boot.
  • ZFS support is lightly tested and only known to work with hybrid kernels (the default). While pure-capability kernels can create ZFS filesystems, they hang if a ZFS file system is used at the root file system. The on-disk format is believed to be stable, but it is not impossible that future releases will be unable to read pools created by this release, particularly pools created on pure-capability kernels.

Using Morello as a Desktop

New installations of the latest CheriBSD release have an option to enable the desktop packages during the install process.

If you have already installed the latest version of CheriBSD but did not install the desktop packages you can add them later; log in as root or use sudo to add the following packages to the system: 

pkg64c install cheri-desktop (provides DRM, Wayland and the general GUI system)
pkg64 install cheri-desktop-hybrid-extras (provides Firefox and other applications)

Make sure that your user ID is in the video group; if not, use: 

pw groupmod video -m username

Add the following lines to /boot/loader.conf: 

dtb_load="YES"
dtb_type="dtb"
dtb_name="/boot/dtb/arm/morello-soc.dtb"

Ensure that a USB keyboard (without an internal hub, see Known Issues) and mouse, as well as an HDMI monitor capable of handling full-HD input (all modern monitors), are connected to the desktop.

Reboot your system and you will be presented with a graphical login screen.

19th December 2022