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Subsystems

JNode's functionality is organized into independent subsystems, each implemented as a set of plugins.

Overview

Subsystem Package Wiki
Filesystems org.jnode.fs.* Filesystem-Layer
Network Stack org.jnode.net.* Network-Stack
Shell org.jnode.shell.* Shell-Commands
GUI/AWT org.jnode.awt.*, org.jnode.gui.* GUI-AWT
Drivers org.jnode.driver.* Driver-Framework

Filesystems

Supported formats (as documented in the wiki):

FS Read Write Notes
FAT12/16/32 ✅ ✅ Best-supported FS
RAM disk (ramfs) ✅ ✅ In-memory
exFAT ✅ ✅
Ext2 ✅ ❌ Read-only; ext3 mounted RO unless journal features absent
ISO9660 ✅ ❌ CD-ROM
NTFS ✅ ❌ Read-only
HFS+ ✅ ❌ Read-only
NFS v2 ✅ ⚠️ Network FS, partial
FTP / SMB ✅ ⚠️ Network FS mounts

Architecture: VFS layer → FSEntry cache → FileSystemType plugins → Block drivers

See Filesystem Layer and Block Device Layer.

Network Stack

Application
    │
    ▼
NetAPI (org.jnode.net.api)
    │
    ▼
Transport: TCP / UDP
    │
    ▼
Internet: IPv4, ICMP, ARP
    │
    ▼
Link: Ethernet, Loopback
    │
    ▼
Driver: RTL8139, NE2000, PRO/100, PCNet

Key components: - NetAPI — Java networking API implementation - NetworkLayerManager — Layer registration & routing - IPv4Protocol — Packet processing, fragmentation reassembly - TCPProtocol — State machine (SYN/ACK, retransmission) - ResolverImpl — DNS resolution (cached)

See Network Stack, TCP Protocol, UDP Protocol.

Shell

The JNode shell (org.jnode.shell) provides:

  • Built-in commands: ls, cd, cat, cp, rm, memory, vminfo, help, alias, history
  • Plugin commands: Dynamically loaded via plugin system
  • Aliases & functions: Persistent across sessions
  • Tab completion: For commands, files, aliases
  • I/O redirection: >, >>, <, |
  • Scripting: .jsh script files

Architecture: Shell → CommandParser → Command plugins → AliasManager

See Shell Commands and Shell Syntax.

GUI / AWT

JNode implements a subset of AWT with custom peers:

Component Implementation
Frame / Window JNodeFramePeer → Thinlet / native
Graphics / Graphics2D JNodeGraphics2D → Video driver
Image JNodeImage → Direct framebuffer
Font JNodeFont → FreeType / built-in
EventQueue JNodeEventQueue → Input drivers

Video drivers: VESA, VGA, ATI, Cirrus, nVidia, VMware SVGA Input drivers: PS/2 keyboard/mouse, USB HID

See GUI/AWT, Video Driver Architecture, Input Drivers.

Drivers

Driver framework (org.jnode.driver):

  1. DeviceManager — Central registry, hotplug
  2. DeviceFinder — Matches devices to drivers (PCI, USB, ACPI)
  3. Bus drivers — PCI, USB, ISA, PCMCIA/CardBus
  4. Device drivers — Extend Driver base class

Major driver categories:

Category Drivers
Storage IDE (ATA/ATAPI), SCSI, RAM disk, Floppy
Network RTL8139, Intel PRO/100 (eepro100), AMD PCNet (LANCE), NE2000, 3c90x, Broadcom 570x, VIA Rhine, Prism2 wireless
Video VGA, VESA, ATI, Cirrus Logic, nVidia, VMware SVGA
Input PS/2 keyboard, PS/2 mouse, USB HID
Serial 16550 UART (0x3f8)

No audio driver is implemented yet.

See Driver Framework, Bus Drivers, PCI Capability Structure.