EDOSx86_64

EDOS boots on UEFI, brings up every core on the machine, and drops you into a compositing desktop with a terminal. It has its own scheduler, filesystem, network stack, USB stack and window system.

/dev/ttyS0

[0.000000] <cpu-0:kernel> Booting...
[0.000000] <cpu-0:kernel> cmdline: "root=UUID=87654321-4321-8765-cba9-987654321fed rootfstype=efs"
[0.000000] <cpu-0:kernel> Initializing frame allocator
[0.000000] <cpu-0:kernel> Mapped kernel heap at 0xffffc00000000000-0xffffc00000100000
[0.000000] <cpu-0:kernel> Initializing acpi tables
[0.000000] <cpu-0:kernel> Initializing apic
[0.000000] <cpu-0:kernel> Initializing hpet
[0.000000] <cpu-0:kernel> APIC frequency: 1000008514 Hz (1000) MHz
[0.000000] <cpu-0:kernel> TSC frequency: 3493922000 Hz (3.49) GHz
[0.001371] <cpu-3:kernel> SYSCALL/SYSRET enabled
[0.008760] <cpu-3:kernel> Initializing scheduler
[0.012664] <cpu-3:kernel> [smp] AP online: LAPIC id 3
[0.013531] <cpu-2:kernel> [smp] AP online: LAPIC id 2
[0.016946] <cpu-1:kernel> [smp] AP online: LAPIC id 1
[0.105367] <cpu-0:kernel> Reaper thread started (tid=1)
[0.106243] <cpu-0:kernel> Evict kthread started (tid=2)
[0.209548] <cpu-0:kernel> Scanning PCI devices...
[0.782741] <cpu-0:kernel> Found 8 PCI devices
[0.795513] <cpu-3:kernel> xhci: version 0.0, 64 slots, 8 ports
[0.797027] <cpu-0:kernel> virtio-gpu: initialised, control=64, cursor=16, blob=false
[0.798908] <cpu-0:kernel> virtio-gpu: 1920x1080 @ 74Hz
[0.808125] <cpu-2:e1000e:k:6> e1000e: initialized, MAC 52:54:00:12:34:56
[0.808210] <cpu-2:e1000e:k:6> net: dhcp: sending DISCOVER
[0.808546] <cpu-2:e1000e:k:6> net: dhcp: received ACK, IP 10.0.2.15
[0.814095] <cpu-3:kernel> xhci: initial enumeration complete
[0.854537] <cpu-1:hda:k:7> hda: /dev/dsp registered
[0.926856] <cpu-0:kernel> verify_kernel_no_phys_aliasing: 2722 kernel-half mappings, no aliases
[0.932629] <cpu-0:ahci:k:4> AHCI CAP: SNCQ=true, NCS=31 (32 command slots)
[0.933450] <cpu-0:ahci:k:4> Found SATA drive on port 1
[0.942643] <cpu-0:window-input:k:15> Window input routing thread started
[1.910146] <cpu-3:system-mount:k:16> Root partition: UUID=87654321-4321-8765-cba9-987654321fed on device 0
[1.910495] <cpu-3:fs:k:14> efs journal: replay scan start tail_seq=2 tail_block=10
[1.910597] <cpu-3:fs:k:14> efs journal: scanned, nothing to replay
[1.910615] <cpu-3:system-mount:k:16> Root filesystem mounted
[1.631909] <cpu-0:system-mount:k:16> Spawned bin/edos-init tid=19 cpu=0
[Terminal] Spawned shell (PID: 26)

Verbatim serial output from a four-core boot, replayed at its own timestamps. The long pause is the PCI scan; the second one is mounting the root filesystem.

The EDOS desktop: four windows showing the process table, the kernel log, a text editor and a widget toolkit demo, over a taskbar. — A 1920×1080 guest on four cores. Every window is a separate userspace process talking to the window manager over shared memory.

ps, on an idle desktop

The kernel's own thread table is the feature list.

Nothing below is a wrapper around someone else's driver. Each of these threads is spawned by name at boot, and each one is a subsystem written for this kernel.

PID	Name	What it does
1	reaper	Tears down dead threads and releases their file descriptors and mappings.
2	evict-inode	Does the blocking half of inode eviction, so no drop path ever waits on disk.
3	klogger	Drains the kernel log ring into /dev/klog, which is what dmesg reads.
4	ahci	Submits and completes NCQ commands, up to 32 tags in flight at once.
5	xhci	Runs USB transfers: HID keyboard and mouse, and mass storage.
6	e1000e	Moves Ethernet frames and drives DHCP and DNS.
7	hda	Intel HDA playback, exposed as /dev/dsp.
8	vga	virtio-gpu scanout and the hardware cursor.
9	tcp-retransmit	TCP timers: retransmission, delayed ACK, and TIME-WAIT expiry.
10	keyboard	Decodes scancodes into key events.
11	mouse	Reads HID boot-protocol reports and moves the pointer.
12	block_writeback	Flushes dirty pages, gated on the journal having committed.
13	journal_committer	Commits EFS metadata transactions.
14	fs	VFS work that cannot run inline: mounts, evictions, async page fill.
15	window-input	Routes keyboard and pointer events to the focused window.
17	ahci_watchdog	Catches NCQ commands that never complete.

A filesystem, not a port

EFS is an extent-based filesystem with a metadata journal, written for this kernel and formatted by efs-mkfs, which runs on the host and inside EDOS. Mounting replays the journal when the last shutdown was unclean. Above it sit a page cache, a block cache, write-back gated on journal commits, and read-ahead; below it, AHCI with native command queuing.

How EFS works

A terminal showing df, mount and stat output in EDOS.

A network stack that talks to the internet

Ethernet, ARP, IPv4 with fragment reassembly, ICMP, UDP and a TCP state machine, plus DHCP and DNS clients. The guest takes its address from DHCP within a millisecond of the NIC coming up. The same driver runs on real Intel I219 and I218 hardware.

Inside the network stack

A terminal in EDOS running ping, dns and wget against the internet.

The desktop is userspace

The kernel owns a window registry and routes input to whichever window has focus. Everything you can see is an ordinary process: edos-wm composites and draws decorations, edos-taskbar and edos-terminal are separate programs, and they share pixel buffers with the compositor through shared memory.

How the window system fits together

The EDOS widget toolkit demo window with buttons, a text input, checkboxes and sliders.

56 seconds, no cuts

Driven from outside the guest

Recorded straight off the framebuffer over QEMU's monitor socket: keystrokes and pointer events go in, PNG frames come out. It is how the OS gets tested.

The tree

What is actually in here

Rust: 112,295 lines across 451 files
Kernel: 50,827 lines, no_std, one binary
Userspace: 125 programs on a forked Rust std
Syscalls: 120, through SYSCALL/SYSRET
Targets: x86_64-unknown-none, x86_64-unknown-edos
History: 1,457 commits

Get it running

Build it, then boot it

git clone https://github.com/edg-l/edos-v2
cd edos-v2
make all      # userspace, kernel, bootable ISO
make run      # QEMU: q35, UEFI, KVM, 4 cores

The kernel builds on plain nightly. Userspace links a real std, so it needs a custom toolchain built from a Rust fork; the build guide walks through it. Prefer a prebuilt image? Downloads.