Phyllome OS has one goal: to let users run their favorite operating system well.
Most PC hardware is designed to work with a single operating system. Since the beginning, the end-users' freedom is serverly restricted, as the operating system is almost always preinstalled. Isn’t there a way to allow users to run their favorite operating system on most hardware?
Virtualization provides a partial answer to this question as it allows the abstraction of the underlying hardware, presenting generic software-based hardware to the operating system. In other words, by means of virtualization, a specific physical computer can be partially abstraced away and made to look generic to an operating system.
To be compatible with physical hardware, including USB controllers or graphic cards, one would still need to use a base operating system that can provide software to drive these physical devices. Most Linux distributions, including Fedora or Debian, ship with a large selection of such drivers, and as such represent another part of the solution to this problem.
The idea behind Phyllome OS is to rely on Linux to provide drivers for specific hardware components and virtualization to provide a limited set of generic virtualized hardware that are already or could be made to work with most operating systems. The burden of hardware compatibility is put on Linux, freeing the operating system underneath, which would only need to provide generic virtual hardware drivers.
Technically speaking, Phyllome OS is an operating system, a free and open source Linux distribution, a Fedora Remix based on Fedora Server designed to leverage hardware-assisted virtualization to run graphically-accelerated UNIX and non-UNIX-based operating systems locally, in a virtual machine, using off-the-shelf hardware and open source software.
Phyllome OS tries to stick to three generic rules or commandments, which can be summed up as follows : Phyllome OS should stay out of users’ way and allow them to run their current operating system well.
Stay out of my way
Run my current operating system[1:1]
Provide a user-friendly interface
libvirt– a powerful and almost ubiquitous virtualization API – and the virtual machine manager software. Having a full-feature desktop environment will allow users to switch more easily between virtual machines and to fall back to a friendly environment whenever they shut down their virtual machine. A headless version of Phyllome OS will eventually be released.
Just enough applications by default, only the necessary software
Favor generic virtual hardware, use passthrough at a last resort
Read-only whenever possible
Encrypt virtual disks by default
Minimize user generated-data storage
Be compatible with proprietary operating systems
There are multiple reasons one would want to rely on virtual machines extensively, or even exclusively, an approach championed by Phyllome OS. Let's list some significant advantages of this approach, but also cover severe limitations.
A software-based/backed computer, or simply a virtual machine, has many advantages over a silicon-based computer:
Relying on a virtual machine as its primarily personal environment comes with several limitations in comparison to using an operating system installed on the hardware (aka known as bare-metal computing). Some of these limitations will be tackled or greatly mitigate one day, others might not.
Performance overhead. Phyllome OS requires resources to run, resources that will not be accessible to guest operating systems.
Suboptimal guest performance. In most cases, running a virtual machine instead of using the physical hardware directly will come with a performance penalty.
Limited out-of-the box hardware support: hardware-assisted virtualization is available on many computers, but rarely activated by default and not always correctly implemented. Users remain at the mercy of good platform firmware and may have to explicitly activate hardware-assisted virtualization in the BIOS/UEFI. Hardware components are often not correctly isolated in IOMMU groups.
Limited features set. Some operating systems are designed to leverage hardware features that may not be accessible to an operating system installed on a virtual machine, or that would require specific developments to be taken advantage of (i.e: a Bluetooth dongle; a Near-field communication chip; etc.)
Increased general complexity. Instead of running just an operating system on top of some physical hardware, any Phyllome OS user would need to manage it as well as their primarily guest operating system. As a result, it might be more difficult to troubleshoot an issue, and it will add a pile of code that the user has to trust.
Decreased general usability. Any physical device attached to a computer won't automatically be made to a guest virtual machine. For some users, it might be considered a hindrance. Phyllome OS relies on Linux drivers. Not all hardware fully supports Linux well, which may force users to rely on device or controllers passthrough. Finally, the use of Phyllome OS will certainly greatly reduce a laptop's battery-life over running a single system.
Lack of guest systems' integration. Phyllome OS provides an optimized virtual machine model tuned to host modern operating systems, but, at the exception of some RPM-based guests operating systems including Phyllome OS itself, does not intent to provide automated ways to deploy guest operating systems (at the moment, Infrastructure as code solutions or instance initialization software like cloud-init do not seem generic enough to satisfy every modern desktop-based operating systems' idiosyncrasies). In other words, contrary to end-to-end operating systems like Qubes OS or the upcoming Spectrum, which are offering ready to use templates or/and applications isolated in virtual machines by default, Phyllome OS delegates to end-users the task to install their favorite operating system, while trying to provide the best possible underlying defaults for each operating system. In this regard, its model is closer to Proxmox, which doesn't make assumptions about how a guest operating system will be deployed.
Run multiple guest operating systems concurrently
Painlessly move to new hardware
Make your current hardware last longer
Go beyond what your physical hardware is capable of
An operating system must possess drivers to allow it to interact with hardware components, devices or peripherals such as storage controllers, graphic cards or keyboards. Each driver has to be specifically written to work with a particular operating system. A specific piece of hardware requires a specific driver tailored for each operating systems out there. Achieving support across operating systems is an almost insurmountable task as there are dozen unique operating systems out there. ↩︎
The industry is even developing drivers for Linux first, at least for certain categories of components such as Network Interface Cards (NICs). ↩︎
There are many types of virtualization. Phyllome OS is primarily focused on paravirtualization, which assumes that an operating system running in a virtualized environment is aware of being virtualized. For any operating systems to run well in such an environment, one would only have to focus on developing and maintaining a set of generic drivers for virtual hardware, a task that is well under way for many popular operating systems, including Linux-based, Darwin-based or Windows NT-based operating systems. ↩︎