QSOE Systems

QSOE A QNX-inspired operating system with selectable kernels.

News: QSOE 0.1 is out — the first public release of the unified two-kernel system (June 2026). Read the announcement →

QSOE ships in two variants that share one userspace and one build system. QSOE/N runs on Skimmer, a microkernel written from scratch for this project (SMP by design); QSOE/L runs on seL4 as its kernel.

Both variants, when compiled, offer the kernel and initrd files directly usable in e.g. U-Boot loader. The userspace is 100% identical across both variants; the only parts produced per-kernel are taskman, the task manager, and libc.so — the C library, which is around 85% shared at the source level and diverges only at the thin layer where it meets the kernel.

The design follows the QNX Neutrino tradition: a small kernel with everything else in userspace, synchronous message-passing IPC, and the resource-manager model for services.

QSOE targets 64-bit RISC-V (RV64, Sv39) on the SiFive HiFive Unmatched (FU740), with QEMU used for day-to-day development. Both QSOE variants now boot on real hardware. Released under Apache-2.0.

Downloads QSOE can be built from source or installed from pre-built binaries. Ready-made images for each release are published at github.com/qsoe-dev/dl (current release: 0.1). The files are: skimmer.bin — the Skimmer microkernel: the kernel of the QSOE/N variant. A raw binary image, loaded by the bootloader (or QEMU) together with the userspace package below. modpkg.cpio — the module package: the shared QSOE userspace (taskman, init, the C library, the shell, drivers and utilities) as a CPIO archive. QSOE/N boots it as an initrd alongside skimmer.bin.

qsoe-l-qemu.elf — the QSOE/L variant (on the seL4 kernel) as a single, self-contained ELF for the QEMU virt machine. It bundles the elfloader, the seL4 kernel, taskman and the userspace together — nothing else is needed to boot. qsoe-l-sifive.elf — the same QSOE/L image, built for the SiFive HiFive Unmatched (FU740) board. mrbml-riscv64.efi — mr-bml, QSOE's own bootloader (an EFI application for RISC-V). It can load either variant and drives the boot menu on real hardware. nvme.img.gz — a ready-to-run, self-booting QEMU disk image (GPT). Its EFI partition holds mr-bml, and an on-disk root holds both kernels — so QEMU boots straight to the mr-bml menu, no -kernel needed. The fastest way to see QSOE run; see Running under QEMU below. virtio.img.gz — a companion root disk used only when running QSOE/L under QEMU (stock seL4 predates the interrupt controller QEMU's NVMe needs, so it mounts its root from a virtio disk instead). Not needed for QSOE/N or for real hardware. In short: to run it in QEMU, grab nvme.img.gz (plus virtio.img.gz for QSOE/L) and see Running under QEMU. To put it on real hardware, you need mrbml-riscv64.efi plus the kernels — QSOE/N uses skimmer.bin + modpkg.cpio, QSOE/L uses one of the qsoe-l-*.elf images — and see Installation. Running under QEMU The quickest way to see QSOE run — no hardware, no -kernel juggling.

The nvme.img download is a self-booting UEFI disk: QEMU's firmware runs mr-bml from it, and mr-bml's menu starts either variant straight off the disk. You need qemu-system-riscv64 — version 11.0.1 or newer for QSOE/N (its NVMe needs the AIA interrupt controller). edk2 RISC-V UEFI firmware — on Debian/Ubuntu, the qemu-efi-riscv64 package. The launcher run-nvme.sh from the os repository — it wraps the right QEMU machine, firmware and disks for each variant, so you don't have to. Run it # unpack the image(s) — add virtio.img.gz only if you want QSOE/L gunzip nvme.img.gz virtio.img.gz

# point the launcher at them and pick a variant from its menu NVME_IMG=./nvme.img VIRTIO_IMG=./virtio.img ./run-nvme.sh Pass n or l to skip the menu (./run-nvme.sh n). The script selects the matching QEMU machine automatically — QSOE/N on the AIA machine with an NVMe root, QSOE/L on the PLIC machine with the virtio root disk. The mr-bml menu and the system console both appear on your terminal; choose a variant and it boots to a login: prompt. Log in as root with password QSOE. Installation Real hardware, real disk. QSOE 0.1 boots on the SiFive HiFive Unmatched (FU740); the SpaceMiT K3 is a future target. This assumes a board already running Linux — you'll be placing files on its existing EFI and boot partitions, so familiarity with the board's firmware is expected. The boot model is simple: mr-bml lives in the EFI System Partition; it reads its menu and the kernels from an ext2/3/4 partition; the chosen variant then mounts its own root from a fs-qrv partition.

Steps Copy mrbml-riscv64.efi into your ESP as EFI/BOOT/BOOTRISCV64.EFI (the UEFI removable-media path), or register it with efibootmgr as a boot entry. On your boot/root filesystem, create /boot/qsoe/ and copy the kernels there: skimmer.bin + modpkg.cpio for QSOE/N, qsoe-l-sifive.elf for QSOE/L. Create /boot/mr-bml/mr-bml.cfg with one entry per variant — for example: # /boot/mr-bml/mr-bml.cfg — adjust the mainfs= partition to your disk menuentry 'QSOE/N (Skimmer)' { kernel /boot/qsoe/skimmer.bin mainfs=/dev/nvme0n1p8 modpkg /boot/qsoe/modpkg.cpio } menuentry 'QSOE/L (seL4)' { kernel /boot/qsoe/qsoe-l-sifive.elf mainfs=/dev/nvme0n1p8 } The mainfs= device names the partition holding the QSOE root filesystem (fs-qrv) — set it to whichever partition you've devoted to QSOE on your board. On real hardware there is no QEMU virtio split: both variants drive the NVMe disk directly. Building from source QSOE is built with a riscv64-linux-gnu- cross toolchain (rv64gc) and a stock make; QEMU is handy for testing. The umbrella repository orchestrates the build and pulls in the component repositories that match its release tag. git clone https://gitlab.com/qsoe/os cd os make prepare # fetch the components for this tag (see component.list) make # build both variants: QSOE/N, then QSOE/L make dist # optional: the QEMU disk images (nvme.img.gz, virtio.img.gz) QSOE/L additionally shallow-clones the seL4 kernel during make prepare. The build produces exactly the files on the Downloads list.