HOSTTYPE reports incorrect value on aarch64 systems

[dkalowsk]

Windows Version

Microsoft Windows [Version 10.0.26100.8037]

WSL Version

2.6.3.0

Are you using WSL 1 or WSL 2?

• WSL 2
• WSL 1

Kernel Version

6.6.87.2-microsoft-standard-WSL2

Distro Version

Ubuntu 24.04

Other Software

No response

Repro Steps

Start a new bash shell
Type echo $HOSTTYPE

Expected Behavior

Expect the value of HOSTTYPE not to be explicitly set. If it is necessary to be set, expectation is that this value would be set to the correct host type. On a Qualcomm SoC based Windows WSL install this should be aarch64.

Actual Behavior

Running echo $HOSTTYPE today results in a value of x86_64 being reported when the value should be aarch64.

Diagnostic Logs

No response

[github-actions]

Logs are required for review from WSL team

If this a feature request, please reply with '/feature'. If this is a question, reply with '/question'.
Otherwise, please attach logs by following the instructions below, your issue will not be reviewed unless they are added. These logs will help us understand what is going on in your machine.

How to collect WSL logs

Download and execute collect-wsl-logs.ps1 in an administrative powershell prompt:

Invoke-WebRequest -UseBasicParsing "https://raw.githubusercontent.com/microsoft/WSL/master/diagnostics/collect-wsl-logs.ps1" -OutFile collect-wsl-logs.ps1
Set-ExecutionPolicy Bypass -Scope Process -Force
.\collect-wsl-logs.ps1

The script will output the path of the log file once done.

If this is a networking issue, please use .\collect-wsl-logs.ps1 -LogProfile networking instead, following the instructions in Collect WSL logs for networking issues

Once completed please upload the output files to this GitHub issue.

See Collect WSL logs (recommended method).

If you choose to email these logs instead of attaching them to the bug, please send them to wsl-gh-logs@microsoft.com with the GitHub issue number in the subject, and include a link to your GitHub issue comment in the message body, and reply with '/emailed-logs'.

[dkalowsk]

Looks like this is explicitly set behavior when looking at the code:

• WSL/src/windows/service/exe/DistributionRegistration.h

  Line 110 in 107104e

  {"HOSTTYPE=x86_64",

• WSL/src/windows/service/inc/wslservice.idl

  Line 98 in 107104e

  cpp_quote("#define LXSS_DISTRO_DEFAULT_ENVIRONMENT \"HOSTTYPE=x86_64\0LANG=en_US.UTF-8\0PATH=/usr/local/sbin:/usr/local/bin:/usr/sbin:/usr/bin:/sbin:/bin:/usr/games:/usr/local/games\0TERM=xterm-256color\0\"")

[dkalowsk]

Logs are required for review from WSL team

If this a feature request, please reply with '/feature'. If this is a question, reply with '/question'. Otherwise, please attach logs by following the instructions below, your issue will not be reviewed unless they are added. These logs will help us understand what is going on in your machine.

How to collect WSL logs
Download and execute collect-wsl-logs.ps1 in an administrative powershell prompt:

Invoke-WebRequest -UseBasicParsing "https://raw.githubusercontent.com/microsoft/WSL/master/diagnostics/collect-wsl-logs.ps1" -OutFile collect-wsl-logs.ps1
Set-ExecutionPolicy Bypass -Scope Process -Force
.\collect-wsl-logs.ps1

The script will output the path of the log file once done.

If this is a networking issue, please use .\collect-wsl-logs.ps1 -LogProfile networking instead, following the instructions in Collect WSL logs for networking issues

Once completed please upload the output files to this GitHub issue.

See Collect WSL logs (recommended method).

If you choose to email these logs instead of attaching them to the bug, please send them to wsl-gh-logs@microsoft.com with the GitHub issue number in the subject, and include a link to your GitHub issue comment in the message body, and reply with '/emailed-logs'.

WslLogs-2026-03-30_11-36-12.zip

[github-actions]

The log file doesn't contain any WSL traces. Please make sure that you reproduced the issue while the log collection was running.

Diagnostic information

Detected appx version: 2.6.3.0
Found no WSL traces in the logs

[dkalowsk]

Second try. It seems the diagnostic information does not pick up the echo command though.

WslLogs-2026-03-31_08-57-57.zip

[github-actions]

Diagnostic information

Detected appx version: 2.6.3.0