Nexus#

Nexus is the VitruvianOS kernel subsystem that bridges the Linux kernel with the BeOS/Haiku runtime. It is implemented as a set of custom Linux kernel modules loaded at boot.

Purpose#

BeOS and Haiku expose a set of kernel APIs that have no direct equivalent in Linux. Nexus implements these APIs as thin kernel modules, allowing the Vitruvian userspace — including the BeOS/Haiku API compatibility layer — to run on an otherwise standard Linux kernel.

Components#

Node Monitor#

The node monitor is one of the core functionalities of Nexus. It provides filesystem event notifications equivalent to the BeOS node_monitor API:

B_ENTRY_CREATED — a new file or directory was created
B_ENTRY_REMOVED — a file or directory was removed
B_ENTRY_MOVED — a file or directory was renamed or moved
B_STAT_CHANGED — file metadata (size, modification time, etc.) changed
B_ATTR_CHANGED — an extended attribute was added, modified, or removed
B_DEVICE_MOUNTED / B_DEVICE_UNMOUNTED — a volume was mounted or unmounted

Internally, Nexus hooks into Linux’s fsnotify subsystem and translates events into BeOS-compatible messages delivered to registered listeners in userspace.

Device and Volume Tracking#

Nexus monitors mount and unmount events via the Linux kernel’s filesystem notification infrastructure and exposes volume information through an API compatible with the BeOS fs_info / device calls. This allows Tracker, the Deskbar, and applications to enumerate mounted volumes and respond to changes in real time.

Messaging Bridge#

Events generated inside the kernel are routed to the VitruvianOS messaging subsystem in userspace. This allows standard BLooper/BHandler code to receive node monitor notifications exactly as it would on Haiku, with no API changes required.

Source#

Nexus has its own repository at github.com/Numerio/Nexus and is included as a submodule in the VitruvianOS repository.