host
Observes state and controls the machines: the trusted base, rather than a guest machine.
The project / 01
Sfere.
by Doppiari
Sfere — reproducible KVM workstation with GPU passthrough, based on Arch Linux
In development · public repository in preparation
One computer, with distinct environments for different activities. The host controls machines, networks and GPU assignment; decisions are explicit and reproducible.
01 / Separate
The six environments.
One control host and five workload domains. Images illustrate the environments; they are not interface screenshots or security indicators.
clean
Trusted accounts and personal activities kept apart from less trusted workloads.
dev
Development and creative work in a dedicated environment.
services
Machines for private services, with declared networking and resources.
dirty
Untrusted software and experimental modifications on a separate network.
lab
Controlled research on a network with no uplink by default.
02 / Control
How it works.
01
The host observes and decides
Machine identity, state and actions are resolved by the host. A guest cannot claim higher trust through its window title.
02
Separate machines
KVM, QEMU and libvirt run activities in distinct machines with verified base images. Separation also depends on the security of the host and hypervisor.
03
Separate networks
The host blocks forwarding between network domains and limits guest access to its own services. The laboratory has no uplink by default.
04
One GPU, one direction
One machine at a time uses the dedicated GPU. Within one boot the ladder only goes down: clean → dev → dirty → lab. Moving up requires rebooting the host. services requires an explicitly reviewed GPU profile and is not a ladder rung.
05
Windows on the desktop
SPICE and Looking Glass bring machine surfaces to the host desktop. Final keyboard and pointer capture checks and Linux session persistence remain open.
06
Disposable machines
The transient disk is implemented and software verified. Restoring agent restrictions and SSH key pins at every boot, and the complete hardware lifecycle, remain unfinished: this is not ready for sensitive data.
03 / Know the boundaries
What it protects. Where it stops.
These are threat-model choices, not a certification. Sfere is in development and does not provide the security properties of Qubes OS.
Intended separation
- Connections between network domains are blocked and access to the host is denied by default, except declared reply, DHCP and DNS traffic.
- Window provenance comes from the host, base images are checked by digest, and GPU handoffs follow the trust ladder.
- No shared folders or implicit SPICE transfers; host clipboard sending is an explicit action to one machine. Machine storage uses encrypted volumes.
What it does not protect
- A compromised host or administrative session compromises control of every machine. The kernel, KVM and QEMU are part of the trusted base.
- A QEMU or hypervisor escape is outside the protection offered. QEMU processes share one identity; per-machine confinement has not yet been proven.
- No guarantee against CPU side channels, compromised firmware or state retained by a GPU after reset.
- Secure Boot does not yet authenticate the initramfs and kernel command line. Physical access and boot tampering remain risks.
- Network and USB drivers still run on the host; input isolation, disposable restarts and intrusion detection remain open work.
- A machine is not protected from its own malicious software. Disk encryption does not protect data on an already unlocked host.
04 / Develop
A roadmap in phases.
In development · public repository in preparation. No promised dates: each phase depends on checks from the previous one.
01 / Foundations
Existing components
Encrypted storage, Ansible automation, KVM/VFIO, networks and desktop components have software checks and partial Nitro evidence. These do not qualify the full installation.
02 / Complete lifecycle
In progress
Complete input, session and disposable-machine checks. Replay installation with frozen revisions and recoverable evidence.
03 / Distribution
To complete
Prepare the public repository, documentation and ISO and Ansible installation paths. Review licences and artifacts before the first release.
04 / More hardware
To validate
Expand evidence beyond the Acer Nitro AN515-55. A configured profile or green CI is not a compatibility certification.
05 / Hardware
Start with a real machine.
The reference is an Acer Nitro AN515-55. Individual component evidence does not equal an accepted complete installation.
- CPU and firmware
- x86_64 with KVM virtualization enabled in firmware and 64-bit UEFI.
- GPU passthrough
- Enabled IOMMU and interrupt remapping; a reviewed PCI group containing only the GPU functions and allowed bridges. One GPU stays with the host and a second may go to the guest. No ACS override.
- Guest display
- A verified display and capture path is required: assigning a GPU alone does not guarantee frames reach Looking Glass.
- Memory and storage
- Size for the selected workloads, including bases, copies, exports and backups. No universal minimum has been published yet.
- Reference machine
- Acer Nitro AN515-55: RTX 3060 Mobile profile and CPU planning for the 8-thread i5-10300H. Component evidence exists; full-pipeline acceptance is still open.
- Single GPU
- A foundation profile without passthrough exists. This does not establish general physical hardware compatibility or qualify the accelerated desktop.
06 / Installation
Coming as an ISO and through Ansible.
No official download is available yet. A repeatable path, hardware evidence and verified recovery instructions are required before release.
07 / FAQ
Before you begin.
Can I download Sfere?
Not yet. Sfere is in development, the public repository is being prepared, and no official downloads are available.
Is it a separate operating system?
It is a reproducible workstation based on Arch Linux, with host and machine configuration through Ansible, KVM, QEMU and libvirt.
Does it provide Qubes OS guarantees?
No. The model differs: no Xen, separate GUI domain or qrexec policy. The host remains part of the trusted base.
Can several machines use the GPU at once?
The dedicated GPU belongs to one machine at a time. Other resources depend on configuration and the available budget.
Is my computer supported?
This is not a supported release yet. The Acer Nitro AN515-55 is the reference; other computers require specific evidence before compatibility can be claimed.
How will it be distributed?
The intended paths are ISO and Ansible. The ISO and public installation guide are coming; a ready installer is not offered today.
Licence
GPL-3.0-or-later from the first public release. This is the intended licence for Sfere. The code, content and trademarks of this website have separate legal notices.