Architecture Support

msvc-kit supports multiple CPU architectures for both host (build machine) and target (output binaries).

Supported Architectures

Architecture	As Host	As Target	Description
x64	✅	✅	64-bit x86 (AMD64)
x86	✅	✅	32-bit x86
arm64	✅	✅	ARM 64-bit
arm	❌	✅	ARM 32-bit (target only)

Host vs Target Architecture

• Host Architecture: The CPU architecture of your build machine
• Target Architecture: The CPU architecture of the compiled binaries

Native Compilation

Build machine and output have the same architecture:

# On x64 machine, build x64 binaries
msvc-kit download --host-arch x64 --arch x64

Cross Compilation

Build on one architecture for another:

# On x64 machine, build ARM64 binaries
msvc-kit download --host-arch x64 --arch arm64

# On x64 machine, build x86 (32-bit) binaries
msvc-kit download --host-arch x64 --arch x86

Architecture Filtering

msvc-kit intelligently filters downloaded packages based on your specified architecture, significantly reducing download size and installation time.

What Gets Downloaded

When you specify an architecture (e.g., --arch x64), msvc-kit downloads only:

Package Type	Filtering Behavior
Tools	Only matching host/target combination (e.g., HostX64.TargetX64)
CRT Libraries	Only matching architecture (e.g., CRT.x64.Desktop)
MFC/ATL	Only matching architecture (e.g., MFC.x64, ATL.x64)
Headers	Always included (architecture-neutral)
Spectre Libraries	Excluded by default (rarely needed)

What Gets Excluded

The following are automatically excluded to minimize download size:

• Other architectures: ARM64, x86, ARM packages when targeting x64
• Spectre-mitigated libraries: .Spectre suffix packages
• Redundant packages: Duplicate architecture variants

Download Size Comparison

Configuration	Approximate Size
All architectures (old behavior)	~2.5 GB
Single architecture (x64)	~300-500 MB
Minimal (tools only)	~150-250 MB

Available Tools

MSVC Compiler Tools

After downloading and setting up the environment, the following MSVC tools are available:

Tool	Description
cl.exe	C/C++ compiler
link.exe	Linker
lib.exe	Static library manager
ml64.exe	MASM assembler (x64)
ml.exe	MASM assembler (x86)
nmake.exe	Microsoft make utility

Windows SDK Tools

The Windows SDK includes additional tools for development and deployment:

Tool	Description
rc.exe	Resource compiler
signtool.exe	Code signing tool
mt.exe	Manifest tool
makecat.exe	Catalog creation tool
makecert.exe	Certificate creation tool
certutil.exe	Certificate utility
mc.exe	Message compiler
midl.exe	MIDL compiler

Using SDK Tools

After activating the environment, SDK tools are available in PATH:

# Activate environment
msvc-kit setup --script --shell powershell | Invoke-Expression

# Sign an executable
signtool sign /a /t http://timestamp.digicert.com myapp.exe

# Compile resources
rc /fo resources.res resources.rc

# Create manifest
mt -manifest app.manifest -outputresource:myapp.exe;1

Tool Paths

The tools are located in:

# MSVC tools
{install_dir}/VC/Tools/MSVC/{version}/bin/Host{host_arch}/{target_arch}/

# SDK tools
{install_dir}/Windows Kits/10/bin/{sdk_version}/{arch}/

Directory Structure

MSVC uses a specific directory structure for cross-compilation:

VC/Tools/MSVC/14.xx/bin/
├── Hostx64/
│   ├── x64/      # x64 host → x64 target (native)
│   ├── x86/      # x64 host → x86 target (cross)
│   └── arm64/    # x64 host → ARM64 target (cross)
├── Hostx86/
│   ├── x86/      # x86 host → x86 target (native)
│   └── x64/      # x86 host → x64 target (cross)
└── Hostarm64/
    ├── arm64/    # ARM64 host → ARM64 target (native)
    ├── x64/      # ARM64 host → x64 target (cross)
    └── x86/      # ARM64 host → x86 target (cross)

Auto-Detection

By default, msvc-kit auto-detects your host architecture:

# Auto-detect host, target x64
msvc-kit download --arch x64

Common Scenarios

Build 32-bit on 64-bit Windows

msvc-kit download --host-arch x64 --arch x86
msvc-kit setup --script --shell powershell | Invoke-Expression

# cl.exe now targets x86
cl /c myfile.cpp  # Produces x86 object file

Build ARM64 for Windows on ARM

# On x64 machine
msvc-kit download --host-arch x64 --arch arm64
msvc-kit setup --script --shell powershell | Invoke-Expression

# cl.exe now targets ARM64
cl /c myfile.cpp  # Produces ARM64 object file

Multi-Architecture Setup

Download multiple architectures:

# Download for multiple targets
msvc-kit download --arch x64
msvc-kit download --arch x86
msvc-kit download --arch arm64

Library API

use msvc_kit::{DownloadOptions, Architecture};

let options = DownloadOptions::builder()
    .arch(Architecture::X64)
    .host_arch(Architecture::X64)
    .target_dir("C:/msvc-kit")
    .build();

// Only x64 packages will be downloaded
let info = msvc_kit::download_msvc(&options).await?;

Cross-Compilation Example

use msvc_kit::{DownloadOptions, Architecture};

// Build ARM64 binaries on x64 host
let options = DownloadOptions::builder()
    .arch(Architecture::Arm64)
    .host_arch(Architecture::X64)
    .target_dir("C:/msvc-kit")
    .build();

// Downloads: HostX64.TargetARM64 tools + ARM64 CRT/MFC/ATL
let info = msvc_kit::download_msvc(&options).await?;