L4h

L4h: Type-1 hypervisor that runs Linux virtual machines on the seL4 microkernel.

L4H is a Type-1 hypervisor built on the seL4 microkernel that runs the Linux kernel as usermode threads without hardware virtualization. It targets 2020+ Intel and AMD CPUs on bare metal and KVM-based VMs. The system uses a single EFI image containing seL4, a guest Linux kernel, and system component processes like root, vmmgr, vmm, trustd, blkd, and netd. It protects VM integrity so that dom0 lacks full control over guests. It supports TPM-backed remote attestation and IOMMU protection for block and network drivers.

L4h at a glance

Best for: Software engineer
Runs on: self-hosted, open source
Pricing: Free
Released: October 2026
Category: AI coding tool
Website: github.com/losfair/l4h

Key features

x86-64 multi-core guest support
TPM-backed remote attestation
Memory hotplug
In-kernel AArch64 emulation
Virtio protocol for emulated devices
IOMMU protection for block and network drivers

Use it for

Running isolated Linux virtual machines
Managing VM lifecycle with fine-grained control
Providing secure block and network devices to VMs
Generating TPM-backed VM attestation

Alternatives to L4h

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Sandkiln — Runs untrusted code in hardware-isolated Firecracker microVMs.
CubeSandbox — Provides sub-60ms cold starts and hardware-level microVM kernel isolation.
llmrun — Check which open models run on your specific GPU or Mac instantly.
LangChain4j — Integrates LLMs and vector stores directly into Java applications.
Pebrel — It brings local shells, remote hosts, and AI command-line tools into one workspace.
Hlock — Pins entire AI agent setups into a portable file to share and run anywhere.
Tunr — Deploys agent-built software and shares local dev servers instantly via a single command.
RunThisLLM — Provides exact hardware and VRAM requirements for over 295 local AI models.
ssh zydra.sh — Run AI agents overnight in a sandboxed virtual machine with built-in Claude Code and Codex.
Daytona — It provisions sandboxes in under 90 milliseconds with full security isolation.

All L4h alternatives