Crossing the WSL Boundary

Files, Paths, systemd and Ports Across the WSL Boundary

A --from-file install has no first-run user prompt and logs in as root. Run adduser dev && usermod -aG sudo dev, put [user] default=dev and [boot] systemd 142,543 =true on four lines of /etc/wsl.conf, then run wsl --terminate Ubuntu-26.04 in PowerShell 55,538 so the next start reads it. That kills everything running in the distribution, so use it only when nothing else is working.

What crosses the WSL2 6 boundary: files over 9P both ways, and ports forwarded to localhost

Files cross the boundary over the 9P protocol, which is slow for the many small files of a PHP project:

Writing and reading 2,000 small PHP files on ext4 and on the Windows driveShell

for d in ~/bench /mnt/c/Users/you/bench; do
  mkdir -p "$d" && cd "$d"; s=$EPOCHREALTIME
  for i in $(seq 2000); do echo "<?php echo $i;" > "f$i.php"; done; cat f*.php > /dev/null
  printf '%-5s %-23s %.2f s\n' "$(findmnt -no FSTYPE -T .)" "$d" "$(bc <<< "$EPOCHREALTIME-$s")"
  cd && rm -rf "$d"
done

Output

ext4  /home/dev/bench         0.15 s
9p    /mnt/c/Users/you/bench  8.69 s

Across several runs the Windows drive was 60 to 80 times slower. So keep projects under ~ and open them from Windows as \\wsl.localhost\Ubuntu-26.04\home\dev, or with VS Code 550 's WSL extension, which runs the editor's back end inside Linux; wslpath -w and wslpath -u convert paths between the two forms. Ports need no setup: in the default NAT mode, WSL forwards them to Windows' localhost, so curl.exe -sI http://localhost/ in PowerShell returns Server: Apache/2.4.66 (Ubuntu 225 ). For access from other machines, set networkingMode=mirrored under [wsl2] in %UserProfile%\.wslconfig (Windows 11 22H2 or later) and allow the port in the Hyper-V firewall.

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Crossing the WSL Boundary