====== 1.2 Set up WSL2 ======

This guide shows how to install Windows Subsystem for Linux (WSL2).

----

===== What is WSL? =====

**WSL** (Windows Subsystem for Linux) allows running Linux directly in Windows:
  * Complete Linux environment
  * Access to Windows files under ''/mnt/c/'', ''/mnt/d/'', etc.
  * Ideal for Linux builds and Docker

<WRAP info>
**Why do we need WSL?**

  * Linux build of OpenSSL
  * WASM build with Emscripten
  * Docker development
</WRAP>

----

===== Quick Installation =====

<code powershell>
# As Administrator in PowerShell:
wsl --install -d Ubuntu-22.04
</code>

This installs:
  * WSL2 components
  * Ubuntu 22.04 LTS
  * Linux kernel

<WRAP important>
After installation: **Restart computer!**
</WRAP>

----

===== Step by Step =====

==== 1. Enable WSL ====

<code powershell>
# Enable WSL and Virtual Machine Platform
dism.exe /online /enable-feature /featurename:Microsoft-Windows-Subsystem-Linux /all /norestart
dism.exe /online /enable-feature /featurename:VirtualMachinePlatform /all /norestart
</code>

==== 2. Restart ====

Restart computer.

==== 3. Set WSL2 as default ====

<code powershell>
wsl --set-default-version 2
</code>

==== 4. Install Linux distribution ====

**Ubuntu (recommended):**
<code powershell>
wsl --install -d Ubuntu-22.04
</code>

**Fedora (alternative):**
<code powershell>
# Fedora manually from Microsoft Store or:
winget install WhitewaterFoundry.Fedora.39.WSL
</code>

==== 5. Set up user ====

On first start, Ubuntu asks for:
  * Username (e.g. ''dev'')
  * Password

----

===== Install Build Tools =====

After WSL installation, build tools need to be installed:

==== Ubuntu ====

<code bash>
# Open WSL
wsl

# Update system
sudo apt update && sudo apt upgrade -y

# Install build tools
sudo apt install -y \
    build-essential \
    perl \
    nasm \
    git \
    cmake \
    pkg-config
</code>

==== Fedora ====

<code bash>
# Open WSL
wsl

# Install build tools
sudo dnf install -y \
    gcc \
    gcc-c++ \
    make \
    perl \
    nasm \
    git \
    cmake
</code>

----

===== Verification =====

<code bash>
# Check compiler
gcc --version
# Should show: gcc (Ubuntu 11.x.x) ...

# Check Perl
perl -v
# Should show: This is perl 5...

# Check NASM
nasm -v
# Should show: NASM version 2.x
</code>

----

===== File Access =====

==== Windows files from WSL ====

All Windows drives are mounted:

<code bash>
# C: drive
ls /mnt/c/

# D: drive (our projects)
ls /mnt/d/Projects/openssl-3.6.0/
</code>

==== WSL files from Windows ====

<code>
\\wsl$\Ubuntu-22.04\home\<user>\
</code>

In Explorer: Type ''\\wsl$'' in the address bar.

----

===== Performance Tips =====

<WRAP tip>
**Files in Linux filesystem are faster!**
</WRAP>

| Location | Performance |
|----------|-------------|
| ''/mnt/d/...'' | Slow (Windows filesystem) |
| ''~/...'' | Fast (Linux filesystem) |

**Recommendation for build:**

<code bash>
# Copy sources to Linux
cp -r /mnt/d/Projects/openssl-3.6.0/src ~/openssl-src

# Build in Linux filesystem
cd ~/openssl-src
./Configure linux-x86_64 --prefix=~/openssl-build
make -j$(nproc)

# Copy result to Windows
cp -r ~/openssl-build /mnt/d/Projects/openssl-3.6.0/linux-build/
</code>

----

===== Common Problems =====

==== "WSL2 requires an update to its kernel component" ====

<code powershell>
# Update WSL kernel
wsl --update
</code>

==== "Virtualization is not enabled" ====

Enable in BIOS:
  * Intel: "Intel Virtualization Technology (VT-x)"
  * AMD: "SVM Mode"

==== Slow I/O Performance ====

Work in Linux filesystem (''~/'') instead of under ''/mnt/''.

----

===== Continue to =====

  * [[.:vorbereitung:emscripten|Install Emscripten SDK]]
  * [[.:build:linux-wsl|Linux Build]]
  * [[.:vorbereitung:start|Back to Preparation]]

----
//Wolfgang van der Stille @ EMSR DATA d.o.o. - Post-Quantum Cryptography Professional//