Can you safely extend the kernel without writing a monolithic driver?

We set the stage for running eBPF on Windows with a clear, practical guide. I’ll explain what it is, why it matters, and how you can add trusted hooks with minimal friction.

The Berkeley Packet Filter evolved into a flexible runtime for observability and networking. This project brings that model to the operating system by integrating community pieces like uBPF and the PREVAIL verifier.

Verification happens in a protected user-mode process, then code runs via interpreter, JIT, or native compilation into signed drivers for HVCI-enabled machines. We focus on kernel-safe hooks today—XDP and socket bind—and show the path from source to trusted load.

We keep things human: what works now, what’s in progress, and how teams pick the right approach. By the end, you’ll have a simple map to implement this feature across your systems.

Key Takeaways

• Understand how the berkeley packet filter model adapts to the Windows kernel safely.
• Learn the runtime pieces: uBPF, PREVAIL, interpreter, JIT, and native driver flow.
• See current networking hooks available today and what to expect next.
• Follow a verified, user-mode-first path to load trusted code into the kernel.
• Decide when signed drivers and HVCI matter for production deployments.
• Walk away with practical steps to build, test, and deploy confidently.

What you’ll achieve by running eBPF on Windows systems today

Here’s what practical capabilities you can unlock by adding ebpf windows to your workflow. I focus on wins you can use immediately—network visibility, early filtering, and low-latency probes.

Today’s model supports XDP and socket bind hooks in the kernel. That means you can filter packets and enforce socket-level policy before user-mode sees traffic. The verifier runs in a protected user-mode process (PREVAIL) and prevents unsafe code from reaching kernel space.

Tracing and diagnostics integrate with Event Tracing for Windows. bpf_printk emits structured events so teams capture runtime signals without heavy agents. This reduces files to process and shortens triage time.

• Reduce event volume and boost performance by dropping noise early.
• Choose interpreter or JIT for experiments, or native drivers for production.
• Keep programs small to limit latency and resource use.

Prerequisites and environment for development and production

I’ll walk you through the platform support, required tooling, and HVCI trade-offs you must know before building.

Target scope: this work supports Windows 10 and Windows Server 2016 and later. That gives you a clear compatibility baseline for kernel hooks and runtime behavior.

The verifier runs in a protected user-mode process (PREVAIL) and thumbs programs before they reach the kernel. HVCI blocks JIT injection, so production on HVCI machines uses native code generation and signed drivers.

Toolchain and setup

• Compile eBPF bytecode with Clang/LLVM and translate where needed with bpf2c.
• Use Libbpf-style APIs for loading and PowerShell helpers for scripting tests.
• Build signed PE drivers with WDK and MSBuild from the Developer Command Prompt.

Keep dev and prod close: match compiler versions, MSBuild settings, and driver signing practice so deployment is predictable. Use the checklist below to validate your environment before writing the first program.

• Confirm target OS versions and kernel compatibility.
• Install WDK, Developer Command Prompt, and eBPF package layout.
• Verify PREVAIL verifier runs and HVCI policies for your images.

Windows vs. Linux kernel introspection: syscalls, hooks, and events

The way a platform surfaces syscalls and hooks changes what you can observe and how.

I’ll compare the two models so you can pick the right approach for tracing and policy.

From syscalls and kernel mode to user mode: ETW vs. Linux tracepoints

Linux exposes a stable syscall surface and mature tracepoints. Tools like Falco, Tetragon, and Tracee hook sys_enter/sys_exit to capture behavior at the system level.

By contrast, Windows emphasizes Win32 APIs and Event Tracing for Windows as the primary pipeline for diagnostics. ETW delivers rich events from kernel and user providers, and many visibility tools rely on it.

Why behavior differs across operating systems and what remains compatible

The big split is abstraction. Linux tracepoints let you attach directly to kernel probes and internal structs. Windows layers those calls behind APIs and ETW channels for compatibility and long-term support.

That means logic built with generic helpers and data-paths translates well between platforms. But helpers tied to Linux internal layouts do not. Expect differences in calling conventions, context layouts, and available events.

In practice, design for cross-platform compatibility: keep programs small, use portable helpers, and add light portability shims where Windows context or event names differ. That approach reduces friction while preserving expected behavior across operating systems.

Inside eBPF for Windows: architecture, hooks, and helpers

I’ll unpack the architecture that secures bytecode, exposes helpers, and lets small programs run safely in kernel mode.

The pipeline starts at source with Clang/LLVM producing Berkeley Packet Filter bytecode. That bytecode is sent to PREVAIL, a protected user-space verifier that enforces bounded loops, memory safety, and termination before any kernel load.

Execution options vary by mode. You can run code via the uBPF interpreter, use a JIT path for speed, or compile to native signed drivers for strict HVCI-enabled deployments.

Hooks, helpers, and compatibility

Today the available hooks include XDP and socket bind. They let you drop packets early and enforce socket-level policy without heavy agents.

The architecture wraps kernel APIs behind an eBPF shim so programs call familiar helpers. That design supports Libbpf-style APIs to ease source compatibility and reduce integration work for loaders.

• Pipeline: source → bytecode → PREVAIL verify → load.
• Execution: interpreter, kernel JIT, or native signed driver.
• Scope: current feature set targets networking hooks with room to grow.

Operationally, helpers expose safe context data and limit direct kernel access. That balance improves safety while keeping portability across this operating system and Linux where possible.

Setting up your development environment on Windows

Before you write code, make the toolchain predictable and repeatable. I’ll walk through the core install steps and quick validations so your builds succeed the first time.

Installing ebpf-for-windows packages and validating your setup

Unpack the ebpf-for-windows NuGet into a stable path (for example, c:\ebpf). Add Clang/LLVM to PATH, and install Visual Studio with the WDK so MSBuild can produce driver images.

Validate the toolchain by compiling a tiny program with clang -target bpf and inspect the object file. Use the provided Convert-BpfToNative.ps1 to run bpf2c, generate a driver project, and build with MSBuild. Verification runs during the build for native code generation—fix failures early.

• Keep compilers and WDK versions aligned across dev machines.
• Place include files and tools in predictable file paths (c:\ebpf).
• Check environment variables, MSBuild versions, and certificates before a full build.

Capture build logs, ETW traces, and object dumps for support. These files speed debugging and make the environment reproducible for your team.

Building your first eBPF program and loading it into the Windows kernel

Start small, prove the path, then iterate. I’ll walk you through a minimal example that compiles, translates, and loads into the kernel so you can verify logging and hooks work end-to-end.

Authoring source code with helpers

Begin with a tiny source code sample that uses helpers. For example:

• SEC(“bind”) HelloWorld that calls bpf_printk(“Hello World!”) to emit a trace event.

This simple program proves logging and attachment without extra data paths. It keeps kernel code minimal and easy to verify.

Compiling to bytecode and inspecting the object file

Compile with clang -target bpf -O2 -Ic:\ebpf\include -c hello_world.c -o out\hello_world.o.

Inspect instructions and data with llvm-objdump -S out\hello_world.o to understand how helpers and registers map to instructions.

Converting to a driver and deploying

Translate the object with the provided PowerShell: c:\ebpf\bin\Convert-BpfToNative.ps1 hello_world.o. The bpf2c step emits C with register emulation and driver boilerplate.

Then build a PE driver with MSBuild. Sign the image as required for preview HVCI-enabled deployments and package the files for operations testing.

• Load the driver, trigger the bind hook, and confirm output via ETW from bpf_printk.
• If the verifier flags issues, fix bounds, loops, or helper misuse and recompile.
• Iterate on the example to learn how kernel code maps to safe, verified bytecode.

Choosing the right execution mode for your system

Pick the execution mode that matches your security posture and performance goals.

I’ll walk through interpreter, JIT, and native paths so you can choose with confidence. Each mode fits a different phase of development and a different operating environment.

When to use interpreter or JIT, and how HVCI affects options

Interpreter mode is great for rapid iteration and lab testing. It keeps the workflow simple and helps debug ebpf programs quickly.

JIT boosts throughput and lowers latency for packet paths. But HVCI on modern windows enforces executable memory integrity. That prevents JIT from writing executable pages in kernel memory, so JIT is disabled on HVCI-enabled hosts.

Native code generation for signed, production-ready drivers

For production you should use native code generation. The toolchain translates bytecode to C, builds a PE image with WDK/MSBuild, and produces signed drivers for kernel mode deployment.

• Interpreter: fast to test, not for signed production builds.
• JIT: high performance where HVCI is not present.
• Native drivers: required for HVCI and regulated environments.

As admins load an ebpf program they can select the mode the runtime should use. I recommend standardizing that choice across your fleet, validating with benchmarks, and documenting audit trails for compliance.

Verification, signing, and deployment workflows

Good deployment begins where compiles end—at verification, signing, and artifact publishing.

I make verification a first-class step so unsafe constructs fail the build with clear errors. Build-time checks flag issues like potential NULL dereference, unchecked pointers, out-of-bounds memory access, or unbounded loops. These errors include actionable hints so you can fix code quickly and rerun the toolchain.

Build-time verification feedback and common verifier failures

The translator bpf2c emits C that the WDK compiles into a PE driver. Verification is integrated into that flow so failures surface during the normal build step. Typical failure modes:

• Unchecked pointer use — add bounds checks or explicit null guards.
• Out-of-bounds memory access — tighten buffer limits and validate lengths.
• Unbounded loops — refactor to bounded iterations or add termination checks.

Driver signing, PE images, and production rollout patterns

The bpf2c-to-WDK path yields a signed PE driver image—the exact artifact the operating system expects for kernel mode execution on secure hosts. Production deployments require signing via standard Windows driver processes and often HVCI-compatible certificates.

For production I recommend deterministic steps and traceable numbers—build IDs, symbol files, and logs. Canary drivers, staged rollouts, and a rapid rollback plan keep risk low. Capture verification output and build logs as CI artifacts so support teams can act fast during incidents.

Observability, event tracing, and debugging eBPF programs

Observability matters when you run verified code in production. I want to show a practical trace workflow that ties runtime logs back to source code and helps you spot hot spots fast.

bpf_printk via Event Tracing for Windows

bpf_printk outputs appear as ETW events. You enable providers, run the program, and filter the stream with familiar tools to validate logic and parameters.

Use structured events to avoid noisy dumps—log only the fields you need and include context like PID or hook name.

Source-level debugging, BTF, and profiling

Compile with BTF so bpf2c emits pragmas that preserve file and line info. The build produces symbol files you can load in Visual Studio or WinDbg for source-level traces.

Profilers use those symbols to find hot spots in ebpf programs—focus on loops and helper calls for quick wins.

• Example workflow: enable providers → attach program → collect ETW events → filter and verify.
• Triage checklist: confirm provider active, validate symbol load, then check event volume and fields.
• Export traces to your analytics pipeline and rotate logs to control storage use.

Performance and safety in production environments

Performance at scale hinges on how much work we push from kernel to user space.

The biggest host impact is the number of events sent to user space and the work done there. Earlier filtering in-kernel cuts context switches and lowers CPU time. That improves throughput and keeps latency predictable.

Reducing transitions, bounding memory, and managing ETW

Keep memory use tight: prefer fixed-size maps and avoid per-event allocations. This reduces memory pressure and makes verifier behavior stable.

Control event volume. ETW is efficient and can be toggled dynamically, but events still add up. Sample, aggregate, or drop low-value signals to protect the host.

• Filter early in the kernel to lower context switches and CPU time.
• Use bounded loops and minimal helper calls so programs run fast and verify cleanly.
• Measure the number of events emitted and set SLOs for alerting on regressions.

Instrument with purpose: profile hot paths, remove unnecessary work, and re-verify after changes. I recommend a steady-state checklist: CPU/memory/time budgets, log caps, and routine profiling cadence to keep production steady.

Where eBPF on Windows systems is headed and how to proceed

Future work aims to extend hooks beyond networking and tighten source compatibility with Libbpf APIs. That effort will expand feature coverage and improve compatibility for the operating system while keeping ETW central for diagnostics.

We recommend a pragmatic approach: start with small, high-impact ebpf programs, validate behavior via ETW, and standardize a signed drivers pipeline for production. Keep development loops short and tests automated.

Treat programs like regular code—use CI, staged rollouts, and profiling to measure impact. Focus on kernel-safe helpers, small maps, and predictable resource use to protect the host.

Watch project updates, contribute portable source, and file issues when you find gaps. Over time, this steady practice will make ebpf windows a durable part of your platform strategy.