NextBSD

A BSD operating system derived from FreeBSD whose low-level system plumbing uses open source components from Darwin: launchd runs as PID 1, services are described by .plist files, hardware events flow through an in-kernel IOKit registry over a Mach-IPC bus, and the network stack is configured by the IPConfiguration daemon talking to configd. It is built on the FreeBSD kernel — rebranded as NextBSD (uname -s is NextBSD) — with ports of Darwin command-line tools making up the majority of the userland.

If you just want to try it, jump to Try it in 5 minutes. If you want the long technical answer to what got ported and how, see PORTING.md.

Heritage

This project is a re-implementation of the original NextBSD, not a fork of it. It reuses some of the original's solutions, such as libxpc, and those carry enhancements from RavynOS. It is however built entirely differently than those original solutions.

What's different from other BSDs?

Other BSDs	NextBSD
init(8) is PID 1	launchd(8) is PID 1
Services configured via rc(8) — rc.conf + rc.d/* scripts	Services configured in .plist files under /System/Library/LaunchDaemons/
The base syslogd(8)	Darwin's syslogd (Apple System Logger / ASL) plus notifyd for the cross-process event bus
Device events via devd/devmatch (FreeBSD), devpubd/drvctl (NetBSD), hotplugd (OpenBSD)	In-kernel IORegistry (/dev/ioregistry) with an IOKit-shaped notification channel, browsed via Darwin's libIOKit / ioreg
Kernel modules via kldload (FreeBSD, .ko) or modload/modctl (NetBSD); OpenBSD dropped loadable modules	Kernel extensions loaded with kextload / kextstat (Darwin kext_tools driving OSKext); the kld* CLIs are retired (the kld syscalls remain)
A base DHCP client — dhclient (FreeBSD), dhcpcd (NetBSD), dhcpleased (OpenBSD)	ipconfigd (Darwin's IPConfiguration) handles DHCPv4 + ARP probing + lease renewal + publishes to SCDynamicStore
mdnsd (if installed) for Bonjour	Darwin's mDNSResponder with its full client API
Nothing equivalent	configd + SCDynamicStore — the system-wide key/value store every Darwin-source daemon expects
Nothing equivalent	Mach IPC in-kernel, plus libsystem_kernel / libdispatch / libxpc / liblaunch / libCoreFoundation in userland
uname -s names the upstream BSD; its own *-version tool	uname -s is NextBSD; nextbsd-version (see Versioning)

Try it in 5 minutes

1. Grab the latest continuous release. Download NextBSD-amd64-<STAMP>.img.zip (the raw disk image; there's also an .iso.zip).

2. Unzip it (any platform's native tools work — macOS Finder, Windows Explorer, unzip on Linux/BSD):

   unzip NextBSD-amd64-*.img.zip

3. Boot it in QEMU (easiest), or dd to a USB stick and boot on bare metal:

   # QEMU, UEFI boot, user-mode network (gives the guest 10.0.2.0/24)
   img=$(echo NextBSD-amd64-*.img)
   qemu-system-x86_64 \
     -accel kvm -cpu host -m 2048 \
     -bios /usr/share/OVMF/OVMF_CODE.fd \
     -drive file="$img",format=raw,if=virtio \
     -nic user,model=e1000 \
     -nographic

4. Wait ~10 seconds. You'll see launchd start its daemons, DHCP fire on em0, syslog come up, and the login: prompt land. Log in as root (no password, hit Enter).

Networking just works

When the image boots, ipconfigd (Darwin's DHCPv4 client) DHCPs the first Ethernet interface it finds. In QEMU's default user-mode network you'll get 10.0.2.15/24, gateway 10.0.2.2, DNS via 10.0.2.3. On real hardware you'll get whatever your DHCP server hands out.

Check it the Darwin way:

ipconfig getifaddr em0          # prints the IP address
ipconfig ifcount                # prints the count of interfaces

(ipconfig(8) here is Darwin's tool with the same name and CLI shape, not FreeBSD's ifconfig(8). Both exist on the image.)

If you want to see the routing table, default route, and so on, standard netstat -rn works as you'd expect.

Try some commands

These are the visible-to-users pieces of the Darwin-source stack that's running. All work today on this image:

# launchctl — the Darwin service-control tool, manages launchd jobs.
launchctl list                       # show every job launchd knows about
launchctl list com.apple.syslogd     # plist for one specific job

# ipconfig — Darwin's IP-config CLI (NOT the same as ifconfig)
ipconfig getifaddr em0
ipconfig ifcount

# ioreg — Darwin's hardware-registry browser, over the in-kernel IORegistry
ioreg -l                             # the full registry tree
ioreg -c PCIDevice                   # filter by class
ioreg -n hostb0                      # find by name

# syslog — Darwin's log-query tool, served by syslogd's ASL store
syslog -F bsd                        # tail the system log in BSD format
syslog -k Sender ipconfigd           # filter by sender

# version identity — NextBSD's own
uname -a                             # ostype reads NextBSD
nextbsd-version                      # userland build version (a timestamp)
nextbsd-version -k                   # the installed kernel's version

# Standard tools are all still here
top
ps aux
pkg info

What's running under the hood

+----------------+      +----------------+      +------------------+
|   launchctl    |----->|    launchd     |<-----| .plist files in  |
| /bin/launchctl |      |  /sbin/launchd |      | /System/Library/ |
+----------------+      | (PID 1)        |      |   LaunchDaemons/ |
                        +----------------+      +------------------+
                                |
                                | starts + monitors
                                v
   +----------------+----------------+---------------+---------------+
   | syslogd + ASL  |   notifyd      | mDNSResponder |   configd     |
   | /var/log/...   | event pub/sub  | Bonjour/DNS-SD| SCDynamicStore|
   +----------------+----------------+---------------+---------------+
                                                     |
                                                     | publishes to
                                                     v
                                            +------------------+
                                            |  ipconfigd       |
                                            |  (DHCP + lease)  |
                                            +------------------+

All of these talk to each other over Mach IPC (in-kernel), in userland via libsystem_kernel.so). All the daemons that need a property-list store talk to configd's SCDynamicStore via libSystemConfiguration.so.

Versioning

NextBSD stamps every build with a single UTC timestamp (YYYYMMDD-HHMMSS), computed once and shared by the image/ISO names, /etc/os-release, and nextbsd-version — so they always agree.

nextbsd-version          # userland build version, e.g. 20260613-224731
nextbsd-version -k       # installed kernel version (its own build time)
nextbsd-version -r       # running kernel version (= uname -r)
cat /etc/os-release      # NAME=NextBSD, VERSION_ID=<same timestamp>, ...

Userland and kernel build in separate repos at different times, so nextbsd-version (userland) and -k/-r (kernel) legitimately differ; that gap is exactly what the command exists to show.

How it's built

NextBSD is assembled from a small chain of repositories, each publishing a rolling continuous release that the next stage ingests:

• nextbsd-kernel — the NextBSD kernel, built as a patch + overlay set on top of FreeBSD (the FreeBSD source tree is never forked in place).
• nextbsd-freebsd-compat — the curated FreeBSD-source base userland, built from a srclist.
• nextbsd-kernel-modules — driver kexts (KPI-matched to the kernel).
• this repo — assembles the bootable image/ISO: it lays the from-source base, builds the Darwin-source userland and the Mach/launchd stack on top, ingests the kernel + driver kexts, and packages a GPT disk image (BIOS + UEFI, read-write UFS root) plus a cd9660 ISO.

It all runs on GitHub Actions' Linux (Ubuntu) runners — there's no FreeBSD hardware in the loop. The kernel and the from-source base are cross-compiled on Linux with a FreeBSD cross-toolchain (clang -target …-freebsd, in a prebuilt toolchain container), so those stages never need a FreeBSD host. The final image assembly (build.sh) then runs inside a FreeBSD VM (vmactions/freebsd-vm) on that same Linux runner — it needs a real FreeBSD userland to run makefs/mkimg and lay the image down — which also boot-tests the result and refreshes the continuous release on a successful main build. Because the kernel and base arrive as published artifacts, build.sh is a CI orchestration step, not a standalone local-build command.

Releases

Each successful main build publishes dated assets to the continuous release — the zip-wrapped GPT disk image (NextBSD-<arch>-<stamp>.img.zip) and ISO (NextBSD-<arch>-<stamp>.iso.zip), each with a matching .sha256. The latest is always at that tag.

Going deeper

• PORTING.md — full technical history of what's been ported and why. Phase-by-phase, with per-component rationale.
• Issues — open work items, scoping questions, planned ports.

License

BSD-2-Clause, with per-component Apache 2.0 / LGPL / MIT / OSF / CMU headers preserved on imported files — see NOTICE.