Comparing WSL versions for Ubuntu on WSL¶

This page explains the main differences between different major versions of WSL and how they affect Ubuntu on WSL.

Background on WSL Versions¶

WSL has had two major versions: WSL 1 and WSL 2. The default version on Windows is WSL 2, although it is possible to run individual Ubuntu instances using either version.

There are significant architectural differences between the two versions, which can impact the behaviour of Ubuntu on WSL.

Overview of major differences between WSL 1 and WSL 2¶

The primary difference between WSL 1 and WSL 2 is that WSL 1 functions as a compatibility layer, translating Linux system calls for the Windows kernel and providing only partial support for Linux system calls. In contrast, WSL 2 runs a full Linux kernel inside a lightweight virtual machine, offering complete system call compatibility. This fundamental architectural difference leads to significant variations in capabilities and performance between the two versions.

As WSL 1 only has partial support for Linux system calls, some programs may not behave as expected when using WSL 1. Additionally, WSL 1 lacks support for graphical applications and systemd, a system and service management suite.

In most cases, applications that are entirely contained in WSL will be faster on WSL 2, particularly for file IO intensive applications. However, WSL 1 has faster access to files mounted from Windows, so for certain use cases, WSL 1 may be faster.

Summary of feature support across WSL versions¶

The differences between WSL 1 and WSL 2 and how it affects Ubuntu can be summarised with the table below:

Feature	WSL 1	WSL 2
Integration between Windows and Linux	Yes	Yes
Fast boot times	Yes	Yes
Small resource footprint compared to traditional Virtual Machines	Yes	Yes
Managed VM	No	Yes
Full Linux Kernel	No	Yes
Full system call compatibility	No	Yes
High performance across OS file systems	Yes	No
systemd support	No	Yes
IPv6 support	Yes	Yes
Graphical application support	No	Yes
Snap support	No	Yes
cloud-init support	No	Yes
Ubuntu Pro for WSL support	No	Yes
Landscape support	No	Yes
Ubuntu Pro Client support	Partial	Yes

How this affects Ubuntu for WSL¶

The differences between WSL 1 and WSL 2 have notable consequences for Ubuntu on WSL, largely due to the lack of systemd support on WSL 1. Systemd is a system and service management suite that Ubuntu and many applications for Ubuntu depend on. Most notably, Snaps and cloud-init do not work on WSL 1 due to the lack of support for systemd. There is also a lack of support for graphical applications on WSL 1.

While Ubuntu works on WSL 1, the experience may be degraded relative to WSL 2. Thus, we generally recommend using WSL 2 unless you have specific requirements. For example, if you make extensive use of file interoperability between WSL and Windows, you may benefit from the better performance of WSL 1 in that specific area.

How this affects Ubuntu Pro for WSL¶

Ubuntu Pro for WSL relies on systemd for much of its functionality, including automatic Pro attachment, so it does not support WSL 1. For the same reason, the Landscape tool for remote management of Ubuntu instances is also not supported on WSL 1. You can still manually attach your WSL 1 instance to Ubuntu Pro using the Ubuntu Pro Client, although some of Ubuntu Pro’s features may not work on WSL 1.