Why Microsoft won't rebuild Windows based on the Linux kernel

A few weeks ago, the opinion of Eric S Raymond, an open source software enthusiast, sparked heated discussions. He believed that Microsoft should rebuild Windows based on the Linux kernel. He believed that the personal computer business was in continuous decline, and Windows was no longer the mainstay of Microsoft's business. Rebuilding could maximize profits. However, Hayden Barnes, who participated in the Ubuntu porting development of Windows Subsystem for Linux, disagreed and believed that Microsoft would not rebuild Windows based on Linux.

Hayden Barnes is a well-known developer who travels between Microsoft and the Linux community. He has helped advance Ubuntu development on Windows Subsystem for Linux (WSL). As a result, he is able to communicate with many Linux developers, open source project personnel, community members, and Microsoft employees. Moreover, he also participates in various briefings on Microsoft products and strategies as an MVP (Microsoft Most Valuable Professional).

Regarding the recent popular saying that "Microsoft should migrate the Windows system core to the Linux kernel", he said that from a product and engineering perspective, Microsoft would never do so under any circumstances.

Before explaining why, Barnes explains why this sentiment keeps popping up on Slashdot and Hacker News:

● Be able to attract users to click

● For open source and Linux advocates, this is an old fantasy.

● The role of Windows is changing. Especially in a world where Android, iOS, macOS, Chrome OS, and Ubuntu are all based on Linux.

● This rationale is growing as Linux adoption grows in Azure and WSL. The Overton Window has shifted.

In this regard, Barnes believes that Microsoft will not rebuild Windows based on the Linux kernel for the following reasons:

1. Kernel

The NT kernel in Windows provides a certain degree of backward compatibility, long-term support, and driver availability, while Linux is still a work in progress. If you want to rebuild based on Linux, it will inevitably cost millions of dollars. Microsoft has many paying customers who can continue to support Windows as is, some for decades.

Rebuilding Windows based on Linux will not help Microsoft save money as Raymond said. Many profitable companies exist to serve existing operating systems. Even if it is eventually based on Linux, it may lead to unhealthy kernel homogenization.

Competition between Windows and macOS will make Linux a better operating system. The ideal outcome is that open source innovation can spread among all operating systems, and open source contributors to Windows and Linux can share the best of both ecosystems.

2. Compatibility

It's not clear if Windows userspace can be migrated from NT to the Linux kernel, whether compatibility can be maintained well, especially for something that has mission-critical applications and is paid for.

Windows does not have the strict separation between kernel space and user space that Linux does. The NT kernel has about 400 documented syscalls and about 1700 documented Win32 API calls. This is a huge amount of work for Windows developers to redeploy and ensure compatibility with their work, which completely exceeds the correct contribution provided by Wine.

Linux only has 313 syscalls on arm64, and another reason is that Microsoft has switched from a syscall translation layer in WSL 1 to a virtualized kernel in WSL 2, so reimplementing the dozens of non-standard ways of leveraging the Linux ABI is painful. It’s one thing to provide an NT-related compatibility layer for Microsoft-owned SQL Server on Linux, and another to provide that for millions of other developers’ apps.

3. Microsoft has invested heavily

In recent years, Microsoft has invested countless manpower and resources in Windows. Microsoft has optimized Windows 10's usability, new features, performance improvements, and other aspects, and has achieved returns. Based on these improvements, through cooperation with OEM manufacturers and the launch of the Surface brand, it has helped revitalize the PC market.

Microsoft has been working hard to make Windows an excellent development platform, with projects including Windows Terminal, PowerToys, Windows Subsystem for Linux, and Visual Studio 2019. The Windows Insider program has also been very successful.

Windows is now the key operating system for many products, including Surface, and it is also a business that Microsoft is focusing on. Internal reorganizations in 2018 and 2020 show that the future of Surface and Windows are now inseparable. Windows powers Xbox, and we are in the midst of a resurgence of PC gaming that is primarily based on Windows.

Microsoft also has the idea of ​​Windows 10X, which is the next operating system concept after Windows 10 (which I think we will gradually get), and future hardware such as Surface Neo is also under consideration.

4. Not necessary

Microsoft can stay relevant without rebuilding Windows on Linux. After abandoning the mobile market, Microsoft has realized the change in the device landscape.

Microsoft recognizes that in today's society, humans use a variety of systems and platforms, including Android, Ubuntu, iOS, macOS, Chrome OS, etc., and in addition to x86 there is also ARM.

Microsoft has shown that they can adapt to this diverse world and launched related products and services on these platforms while ensuring the competitiveness of Windows in traditional fields. Microsoft is currently promoting innovation in the mobile field based on Android and iOS, not only porting Microsoft Office, but also many excellent applications including Microsoft Launcher, and recently launched the Surface Duo mobile phone equipped with Android system.

On the Ubuntu system, Microsoft has launched many tools for Linux workstations, such as Code, .NET, Azure tools, Teams, PowerShell, Sysinternals for Linux, and the upcoming Edge browser. Do you want to run Ubuntu on Azure? Microsoft is ready for you and works closely with Canonical to give you a wonderful experience.

Rather than worrying about whether Microsoft will rebuild Windows based on Linux, the more interesting question is how far Microsoft can go in open source? We have already seen Windows Terminal, PowerToys and other Windows components open source. The more logical and practical goal is that Microsoft will continue to open Windows components and the Windows development process, and even go beyond the scope of the Windows Insider project to provide benefits to other systems.