Emuko: Fast RISC-V emulator written in Rust, boots Linux

Hacker News · Feb 27, 2026 · Collected from RSS

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emuko Fast RISC-V emulator written in Rust. Boots Linux. emuko.dev Features RV64IMAFDC with M/S/U privilege levels and Sv39 virtual memory JIT compilation for ARM64 and x86_64 hosts (adaptive selection) Full Linux boot with BusyBox userland and interactive shell Snapshot/restore for saving and resuming full machine state Daemon mode with HTTP API and live UART command injection Differential checker to validate JIT against interpreter Peripherals: UART 16550, CLINT, PLIC, SBI 1.0, FDT generation Single dependency (zstd), pure Rust RISC-V Emulator Comparison (emuko vs others) This is a direct comparison with commonly used RISC-V emulators/simulators: QEMU, Spike, and Renode. Legend: ✅ = built in / directly documented, — = not built in (or not documented in the referenced source). Feature emuko QEMU (RISC-V virt) Spike (riscv-isa-sim) Renode JIT / dynamic translation backend ✅ ✅ — — Snapshot save + restore ✅ ✅ — ✅ Autosnapshot (periodic) ✅ — — ✅ HTTP API for machine control ✅ — — — WebSocket UART console endpoint ✅ — — — Scriptable UART host bridge primitives ✅ — — ✅ One-command Debian kernel/initrd download with SHA256 verification ✅ — — — Built-in JIT-vs-interpreter differential checker ✅ — — — GDB debugging workflow — ✅ ✅ ✅ Large RISC-V board/device ecosystem (PCIe/virtio on virt) — ✅ — — Multi-node simulation focus — — — ✅ Broad ISA extension coverage (incl. RVV, crypto, etc.) — — ✅ — Sources: QEMU RISC-V virt machine docs: https://www.qemu.org/docs/master/system/riscv/virt.html QEMU RISC-V system overview: https://www.qemu.org/docs/master/system/target-riscv.html QEMU GDB usage: https://www.qemu.org/docs/master/system/gdb.html QMP reference: https://www.qemu.org/docs/master/interop/qmp-spec.html QEMU monitor (savevm, loadvm): https://www.qemu.org/docs/master/system/monitor.html QEMU VM snapshots: https://www.qemu.org/docs/master/system/images.html Spike README: https://github.com/riscv-software-src/riscv-isa-sim Renode README: https://github.com/renode/renode Renode state save/load + autosave: https://renode.readthedocs.io/en/latest/basic/saving.html Renode GDB integration: https://renode.readthedocs.io/en/latest/debugging/gdb.html Renode UART host integration: https://renode.readthedocs.io/en/latest/host-integration/uart.html Build cargo build --release The main binary is target/release/emuko. Quick Start 1. Download a kernel alias emuko=target/release/emuko emuko dow Downloads the Debian RISC-V netboot kernel and initrd to ~/.emuko/ with SHA256 verification. 2. Boot Linux emuko start This starts the emulator daemon and attaches an interactive console. You'll see the kernel boot and get a shell prompt. Keyboard shortcuts: Key Action Ctrl+] Detach from console (daemon keeps running) Ctrl+C Sent to guest (interrupt running command) Ctrl+D Sent to guest (EOF) 3. Reattach or control emuko start # reattach console to running daemon emuko dump # print CPU state emuko stop # pause execution emuko con # continue execution emuko step 1000 # step N instructions emuko snap # take a snapshot emuko kill # shut down daemon The daemon exposes an HTTP API at http://127.0.0.1:7788/v1/api/ and a WebSocket console at ws://127.0.0.1:7788/v1/ws/uart. Snapshots emuko snap # take a snapshot now emuko snap 5000000 # auto-snapshot every 5M steps emuko snap stop # disable auto-snapshots emuko ls # list snapshots emuko restore <snapshot> # restore a snapshot Configuration Pass options after emuko start, or set via environment variables or emuko.yml: Option Env Var Default Description --ram-size RAM_SIZE 1 GB RAM in bytes --backend EMUKO_BACKEND adaptive adaptive, arm64_jit, amd64_jit, arm64, x86_64 --bootargs BOOTARGS serial console Kernel command line Getting a Kernel Use emuko dow (see Quick Start above) or grab pre-built images from DQIB (Debian Quick Image Baker). To download a specific set: emuko dow debian-netboot License Apache 2.0. See LICENSE.