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This Christmas eve, team DragonFly released the 54th version, DragonFly BSD 5.4.1, a free and open-source Unix-like operating system. This version comes with a new system compiler in GCC 8, improved NUMA support, a large number of network and virtual machine driver updates. This release also has significant HAMMER2 improvements and better WLAN interface handling.

What’s new in DragonFly BSD 5.4.1

Big-ticket items

  • This release comes with much better support for asymmetric NUMA (Non-Uniform Memory Access) configurations. Both the memory subsystem and the scheduler now understand the functionality of Threadripper 2990WX’s architecture.
  • The team at DragonFly has been working on improving fairness for shared-vs-exclusive lock clashes, reducing cache ping-ponging due to non-contending SMP locks.
  • This release comes with major updates to dports.
  • Concurrency across multiple ttys and ptys have been improved.


DragonFly 5.4.1 comes with GCC 8.0, and runs as the default compiler. It is also used for building dports.


  • This release comes with HAMMER2 which is the default root filesystem in non-clustered mode.
  • It increases bulkfree cache to reduce the number of iterations required.
  • It also fixed numerous bugs.
  • This release comes with improved support on low-memory machines.
  • This release comes with significant pre-work on the XOP API to help support future networked operations.

Major changes

Security Issues

  • The machdep.spectre_supportsysctl can be now used to probe the spectre support, and machdep.spectre_mitigation sysctl to enable/disable support.
  • The default /root perms has been changed from 755 to 700 in the build template.
  • Delayed FP state has been removed to avoid the known side-channel attack.
  • This release comes with clean FP state on switch to avoid known side-channel attack.
  • There zero user registers on entry into kernel (syscall, interrupt, or exception) to avoid speculative side-channel attacks.


  • This release comes with updated drm to match Linux kernel 4.7.10 in a number of locations.
  • The radeon driver has been updated; currently matches Linux 3.18.
  • CVE-2018-8897 has been mitigated.
  • This release comes with an added timer support x2apic
  • A private_data field thas been added to struct file for improving application support.
  • SPINLOCK and acpi_timer performance has been improved.
  • A dirty vnode management facility has been added
  • Bottlenecks from the rlimit handling code has been removed.
  • The size of the vm_object hash table has been increased by 4x to reduce collisions.
  • Concurrent tmpfs and allocvnode() has been improved.
  • The namecache performance has been improved.
  • The syscall path has been optimized to improve performance.

Driver updates

  • With this release, serial-output-only installs are now possible.
  • This version of DragonFly comes with  virtio_balloon memory driver.
  • With this release, /dev/sndstat can now be opened multiple times by the same device.
  • MosChip PCIe serial communications are now supported.
  • Missing descriptions for usb4bsd C610/X99 controllers have been added.
  • This release comes with an added support for PCIe serial com and console support.
  • Old PCI and ISA serial drivers have been removed.


  • This release comes with an added rc support for ipfw3.
  • Vis(3) and unvis(3) have been updated.
  • With this release, pciconf database has been updated.
  • tcsetsid() has been added to libc.
  • The buildworld concurrency has been improved.


  • With this release, the network tunnel driver, tun(4), has been cleaned up and updated. It’s now clonable for anyone building VPN links.
  • The arp issue in the bridge code has now been fixed.
  • Interface groups are now supported in the kernel and pf(4).
  • The ENA(Elastic Network Adapter) network driver has been added to DragonFly 5.4.1.

Package updates

With this release, there are a number of options for running a web browser on DragonFly which includes, Chromium, Firefox, Opera, Midori, Palemoon, etc.

Users are appreciating the efforts taken for this project and especially, the hammer storage is being appreciated. Though few users are complaining about the speed of the process which is very slow. The HAMMER2 used in this release is BSD licensed so it might have better potential as a Linux kernel module.

Read more about this release on DragonFly BSD.

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