Support for Windows guests

[unsuman]

Description

Lima currently supports three guest OS types (Linux, Darwin, FreeBSD). Guest provisioning is handled via cloud-init, which generates a cidata ISO9660 image containing cloud-config.yaml, boot scripts, and provisioning data. None of this applies to Windows.

Driver Constraints

• VZ (Virtualization.framework) cannot be used for Windows guests because it does not expose a virtual TPM (vTPM) device, which is required by Windows 11.

• WSL2 is also not applicable because it runs Linux distributions inside Windows, not the other way around.

• QEMU is the preferred driver. QEMU supports TPM (via swtpm), UEFI firmware with Secure Boot via OVMF, and the full range of virtual hardware Windows expects.

Provisioning: autounattend.xml instead of cloud-init

Windows does not support cloud-init. Instead, unattended installation is driven by Windows Answer Files (autounattend.xml). The answer file handles:

• Disk partitioning and OS installation
• User account creation
• Enabling OpenSSH Server for remote access
• Running first-logon scripts (similar to Lima's provisioning scripts)
• Injecting SSH public keys

[afbjorklund]

macOS does not support cloud-init either, but there lima provides a "fakecloudinit" adapter

You could make a conversion shim for this, that would translate to the local implementation?

// Package fakecloudinit is a fake cloud-init implementation for macOS.
//
// TODO: support other OS that does not have cloud-init.

[Nesar976]

Hi @unsuman , @afbjorklund , I’d like to work on this.

My plan is to introduce a small conversion layer similar to fakecloudinit that translates Lima provisioning into a Windows-compatible autounattend.xml setup. I’ll start with basic provisioning (disk setup, user creation, SSH access) and iterate from there.
Please let me know if this approach aligns with your expectations.

[unsuman]

Thank you for your interest in working on this! However, we’ve submitted this as a potential proposal idea for the LFX Mentorship 2026 Term 2.
cncf/mentoring#1766

Feel free to explore any other issues and if we’re accepted, you can submit a proposal to work on this and others as specified above.

[Nesar976]

Hi @unsuman, thanks for the clarification — I wasn’t aware this was planned as an LFX mentorship project, so I initially thought of contributing via a PR.

My idea was to introduce a small conversion layer (similar to fakecloudinit) that maps Lima provisioning into a Windows-compatible autounattend.xml setup. I planned to start minimal (disk setup, user creation, SSH access) and then extend it incrementally, while keeping the implementation lightweight to avoid duplication.

I’ll pick up another issue and start contributing there. Thanks again!

[AkihiroSuda]

I don't think we should have fakecloludinit for non-Unix guests.
For Windows, Lima should just generate autounattend.xml directly.

[Nesar976]

Hi @AkihiroSuda, thanks for the clarification — that makes sense.

In that case, instead of a fakecloudinit-style layer, the direction would be to generate autounattend.xml directly from Lima’s provisioning data, starting with a minimal setup (disk config, user creation, SSH access) and expanding as needed.

Does this sound like the right direction?

[AkihiroSuda]

We have to investigate whether we want to use Hyper-V directly or use HCS
https://learn.microsoft.com/en-us/virtualization/api/hcs/schemareference

HCS is the basis of WSL2, so it might be available in the "Home Edition" of Windows 11, while Hyper-V is only available in Pro, Enterprise, etc. ?

Also, the support for 9p seems only available in HCS (correct me if I'm wrong)
https://learn.microsoft.com/en-us/virtualization/api/hcs/schemareference#Plan9

EDIT this comment was about Windows host, not about Windows guest. So this is an off-topic here.