3-Phase System Check: How WSA Installer Validates Your System

Why 3 Phases?

Previous versions of WSA Installer did basic system checks. v1.2 introduces a comprehensive 3-phase validation that catches issues early and provides automatic fixes.

Phase 1: System Validation

The first phase validates your Windows environment is ready for WSA.

Windows Version Detection

Detects whether you're running Windows 10 or Windows 11:

import sys
version = sys.getwindowsversion()
if version.build >= 22000:
    print("Windows 11 detected")
else:
    print(f"Windows 10 build {version.build} detected")

Virtualization Detection

Uses 5 independent methods to detect hardware virtualization:

• CPUID instruction — Direct CPU feature detection
• WMIC — Windows Management Instrumentation
• systeminfo — System information query
• PowerShell — Get-CimInstance Win32_Processor
• Registry — HKLM\SOFTWARE\Microsoft\Windows\CurrentVersion\HyperVision

Feature Status Check

Checks the status of required Windows features:

• Hyper-V — Microsoft's hardware virtualization
• VirtualMachinePlatform — Required for WSA VM
• HypervisorPlatform — Hypervisor interface
• Windows Subsystem for Linux — Shared infrastructure

Phase 2: Bundle Detection

The second phase checks for existing WSA bundles and cache.

Bundle Search Order

• 1. Current directory — Check for bundle.wsa
• 2. Parent directory — Check for bundle.wsa
• 3. Temp directory — Check for cached bundles
• 4. Install directory — Check for previously extracted files

Bundle Verification

If a bundle is found, it's verified before use:

• File size check — Must be > 1GB
• SHA-256 hash verification
• 7z archive integrity check
• Filelist.txt validation

Cache Management

WSA Installer maintains a cache of previously downloaded bundles:

%TEMP%\WSA-Installer\
├── bundle_wsa_2407.40000.4.0.7z
├── bundle_wsa_2407.40000.4.0.hash
└── bundle_wsa_2407.40000.4.0.extracted\

Phase 3: Virtualization Bypass

The third phase automatically fixes compatibility issues. See the dedicated blog post for full details.

The Complete Flow

Here's the complete 3-phase check flow:

START
  │
  ├── Phase 1: System Validation
  │   ├── Windows version? ──────────── Win10/Win11
  │   ├── Virtualization? ────────────── Yes/No
  │   ├── Hyper-V? ──────────────────── Enabled/Disabled
  │   ├── VirtualMachinePlatform? ────── Enabled/Disabled
  │   └── HypervisorPlatform? ────────── Enabled/Disabled
  │
  ├── Phase 2: Bundle Detection
  │   ├── Bundle.wsa found? ─────────── Yes/No
  │   ├── Cache valid? ───────────────── Yes/No
  │   └── Hash verified? ─────────────── Yes/No
  │
  ├── Phase 3: Virtualization Bypass (if needed)
  │   ├── Enable Hyper-V
  │   ├── Uninstall problematic KBs
  │   ├── Configure WSL2
  │   ├── Add Defender exclusion
  │   ├── Disable VBS
  │   └── Fix FsDepends
  │
  └── RESULT: Ready to install / Issues found

Error Reporting

If any phase fails, WSA Installer shows a detailed error report:

• What was checked
• What failed
• Why it failed
• How to fix it (manual or automatic)

Performance

The 3-phase check is designed to be fast:

• Phase 1: ~2 seconds
• Phase 2: ~1 second (if bundle found)
• Phase 3: ~10-30 seconds (if fixes needed)
• Total: ~3-35 seconds depending on system

Logging

All checks are logged to wsa_activity.log:

[2026-08-19 10:30:15] Phase 1: System Validation
[2026-08-19 10:30:16]   Windows 11 build 22621
[2026-08-19 10:30:16]   Virtualization: Enabled
[2026-08-19 10:30:17]   Hyper-V: Enabled
[2026-08-19 10:30:17] Phase 2: Bundle Detection
[2026-08-19 10:30:18]   bundle.wsa found: 1.21 GB
[2026-08-19 10:30:18]   Hash verified: OK
[2026-08-19 10:30:18] Phase 3: Virtualization Bypass
[2026-08-19 10:30:18]   Skipped (no issues found)