initrdg

initrd binary to experiment with WSLg in Windows 10

⚠️ Disclaimer: At time of this writing, WSLg (GUI support in WSL) is not available in Windows 10. This project is just to experiment with that. This is not a replacement of actual WSLg shipped in Windows 11. Please use this only for fun and experimental purposes. Also backup your WSL setup before using this program. This may totally destroy your current WSL environment.

Table of contents

• Assumptions
• Preparation
• How to use
• Differences with initrd
• Caveats
• Acknowledgments
• License

Assumptions

This program assumes some certain aspects by default which are as following:

• WSL msix is extracted at C:\WSL path. Feel free to change the folder path. But you also have to change the path in SystemDistro.reg file and the environment variable listed in how to use section.

• This project has been tested in Windows 10 21H1 Version 10.0.19043.928. The messages between initrd and Lxss service are varied with Windows versions. Feel free to modify this project for your own Windows version.

• Every binaries are compiled in Alpine Linux and with musl libc & gcc. Feel free to use any compiler toolchain and libc.

Preparation

⚠️ Warning: The following steps requires read/write permission in System32 folder. Any type of wrong step may make your entire WSL setup or even the operating system unusable.

• Download WSL msixbundle package from WSL Release page. In that msixbundle, extract the ARM64 or X64 msix according to your CPU architecture. Extract the msix in C:\WSL path (default) or at your choice (need modification). Use any program that can extract from ZIP format e.g. unzip, 7zip etc.

• In C:\WSL directory, remove the following two lines from wslg.rdp file. This enables full desktop mode instead of separate application window mode.

remoteapplicationmode:i:1
remoteapplicationprogram:s:dummy-entry

• In C:\WSL directory, convert the system.vhd to ext4.vhdx file. Because Lxss service expects the WSL distribution in exactly ext4.vhdx named file. Use this command in Powershell.

Convert-VHD -Path "system.vhd" -DestinationPath "ext4.vhdx"

• Double click on the SystemDistro.reg file to register the ext4.vhdx file with "system" named distribution in WSL2 environment. Make sure there is no distribution with "system" name before that.

• Backup and Rename the initrd.img file in C:\Windows\System32\lxss\tools directory to something else. Clone this repository. Run make command in any GNU/Linux distribution to compile the initrd.img file. Copy the newly compiled initrd.img file to that C:\Windows\System32\lxss\tools directory.

• Check out Win10 branch in my fork of wslg. Run make command in WSLGd directory to compile WSLGd static executable. Remember the full path of that for later use.

How to use

• Run your preferred GNU/Linux distribution in WSL2.

• Execute wsl.exe -d system -u root to run the newly registered "system" distribution with root user.

• Run the following commands in both your running distribution and "system" distribution as well. This step may not required in future, just thoughts. The <guid> is retrieved from hcsdiag.exe list command output.

export WAYLAND_DISPLAY=wayland-0
export DISPLAY=:0
export XDG_RUNTIME_DIR=/mnt/wsl/runtime-dir
export PULSE_SERVER=/mnt/wsl/PulseServer
export WSL2_INSTALL_PATH="C:\\WSL"
export WSL2_EXECUTION_ALIAS_PATH="C:\\WSL"
export WSL2_WESTON_SHELL_OVERRIDE=desktop-shell
export WSL2_VM_ID=<guid>

• Run previously compiled WSLGd binary in "system" distribution. The WSLGd will invoke C:\WSL\msrdc.exe executable and show a warning window to accept network connections. Click on "Connect" button to allow it.

• Now run any GUI program in your distribution 🎉

Differences with initrd

This project is not an replacement of initrd binary which already exists in Windows 10 and 11 systems. This does NOT do:

• Import or export distributions in WSL2.
• Convert distributions from WSL1 to WSL2 or vice-versa.
• Create or attach swap file.
• Execute localhost or telemetry processes.
• Compact memory.

Caveats

• Every GUI applications are in one big window. Because Wayland apps become unresponsive in rdprail-shell which is used by-default to show apps in separate windows.

Acknowledgments

Everyone in the discussions:

• wslg#82
• wslg#347
• wslg#441
• wslg#446

Free and Open source projects:

• musl libc
• ArchLinux's mkinitcpio

License

This project is licensed under GNU General Public License version 3 or any later version at your option. See LICENSE file for further details.