A from-scratch
x86_64 kernel.
Boots into ring 3.
Open Cube OS 2.2.0 boots through its kernel (L0), launches the default ring-3 application — the ush user shell with 251 commands over the SYS_L1SVC service surface — and falls back to a WinRE-style recovery shell (oc>) whenever the ring-3 world cannot start. Not a Linux fork: 130,572 lines of original code, Apache 2.0.
[oc] Open Cube OS 2.2.0 kmain entered boot complete .................... OK crash recovery armed ............. OK l1 launcher: booting 'ush' (ring 3, 53800 bytes) Open Cube OS User-space Shell (WP-08) ush> mounts VFS mount table: / ramfs ush> lsblk Block devices: (none attached) ush> cryptotest AES-128-GCM NIST vectors: PASS (all) ush> exit l1 launcher: default L1 app exited; recovery shell taking over oc> █
Features
A real kernel, not a demo: preemptive scheduling, four-level paging, ring-3 processes, a VFS over four filesystems, a full TCP/IP stack with TLS and SSH (client and server), 16 driver families, crash dumps, hardware watchdogs, and OTA A/B updates.
Hybrid BIOS + UEFI
One ISO boots both firmware paths through GRUB 2.12, with an A/B slot menu and the kernel attached as its own install payload.
PMM / VMM / heap
Bitmap physical manager over the multiboot2 map, 4-level paging, kmalloc with coalescing and stack/heap growth by page fault.
Preemptive scheduler
Priority + round-robin over TCBs, 100 Hz tick, soft-timer wheel, IST-separated exception stacks, live 3/3 trap self-test on every boot.
User programs
ELF loader, 54 syscalls, fork/exec/pipes/signals/select/mmap, an in-tree shared-object loader with dlsym and PIE relocations - and the SYS_L1SVC + SYS_NETCMD service bridges.
TCP/IP + TLS + SSH
Seven NIC driver families, congestion-controlled TCP, sockets, firewall, an HTTPS client with X.509 verification, and a real sshd in-guest.
NVMe to FAT32
AHCI/ATA-DMA/NVMe/virtio/USB-MSC/SD/SCSI block devices; FAT32 with LFN, exFAT, ext4, ramfs; a persistent /etc volume.
Four USB stacks
UHCI, OHCI, EHCI and xHCI host controllers with MSC, HID, serial and audio classes - hotplug included.
Crash + watchdogs
Register dumps to serial and crashlogs to /etc, Intel TCO and ACPI WDAT hardware watchdogs, policy watchdog slots, health alarms and JSON export.
Two shells
ush boots in ring 3 with 133 service commands plus built-ins (pipes, jobs, wildcards, aliases, editor); the oc> recovery shell keeps 99 commands for when the ring-3 world cannot start.
Terminal UI
Desktop, taskbar, menus, forms, editor and system apps on the framebuffer - plus a Chinese console layer with a pinyin IME.
A/B updates
Manifest-driven OTA with SHA256 + signature verification, staged install onto the inactive slot, automatic rollback.
17 services / 158 ops
The ring-3 surface is the contract: 17 SYS_L1SVC service categories with 158 numbered ops, every operational command class behind one syscall. The v1→v2 mapping table ships in INTERFACES.md.
Quick start
From download to an oc> prompt in about a minute. Any machine with QEMU works; real hardware boots the same ISO from USB.
Boot the ISO in QEMU
One command - the ISO is self-contained, 512 MiB of RAM is comfortable.
Watch it come up
One OK line per subsystem: multiboot2 handshake, long mode, framebuffer, IDT, PIT, PMM, drivers, VFS, network, shell.
Drive the machine
Bring up networking, pull a page, inspect the system - all from the recovery shell.
Go deeper
The documentation center has the user manual, the command reference, the developer handbook, the L1 extension guide and the architecture deep-dives.
It really runs
Captured from the release ISO in QEMU - the BIOS and the UEFI boot path, straight to the shell prompt.
The two-layer idea
“Everything is extensible” is the whole design: L0 is a complete kernel and nothing more; everything users actually see above the shell is meant to be an L1 module riding the surface.
Open Cube OS
The kernel + the oc> recovery shell. Boots, diagnoses, repairs, installs, updates. This repository.
Upper extensions
The ring-3 service world - ush, ld.so and the dynamic-linking programs ship in-tree under l1apps/; every operational command class runs behind the 17-service SYS_L1SVC surface.
Cube OS = L0 + L1
The roadmap: a complete, daily-usable system assembled from the kernel below and the extension ecosystem above.
See the whole picture
Boot flow, every kernel subsystem, the TUI desktop and the 17-service L1SVC surface, each on its own page.