Tidemark

Tidemark is a browser-hosted RISC-V Linux userland environment.

This site explains repository boundaries, current implementation structure, and the contracts between layers.

Repositories

Repository	Primary language	Current role
kernel	Rust	RISC-V Linux userland kernel compiled for WebAssembly targets.
runtime	TypeScript	Browser worker runtime that runs guest processes on top of the kernel.
sdk	TypeScript	Higher-level API for applications using the runtime.

The dependency direction is intentionally one-way:

flowchart LR
  App["application"]
  SDK["@tidemarksh/sdk"]
  Runtime["runtime package"]
  KernelWasm["kernel WebAssembly bytes"]
  Kernel["tidemarksh/kernel"]

  App --> SDK
  App --> Runtime
  SDK --> Runtime
  Runtime --> KernelWasm
  Kernel --> KernelWasm

The SDK builds on the runtime API, and the runtime expects kernel WebAssembly bytes at creation time.

What Tidemark Is

Tidemark is not a full virtual machine monitor and it is not a browser operating system. The current implementation focuses on running RISC-V Linux userland programs inside WebAssembly and browser worker infrastructure.

It can be used as an application-embedded guest execution environment for running Linux userland binaries, command-line tools, language runtimes, build steps, package-backed file layers, and terminal-like workflows inside a browser or compatible worker host. The value is not only CPU emulation; it is the combination of guest execution, filesystem state, process orchestration, stdio, network bridge hooks, and SDK-level provisioning.

At a high level, Tidemark separates guest semantics from browser orchestration and product-level provisioning:

flowchart TB
  App["application"]
  SDK["sdk<br/>high-level API and package providers"]
  Runtime["runtime<br/>workers, process lifecycle, host bridges"]
  Kernel["kernel<br/>RISC-V execution, ELF, memory, syscalls"]
  Guest["RISC-V Linux userland program"]

  App --> SDK
  App --> Runtime
  SDK --> Runtime
  Runtime --> Kernel
  Kernel --> Guest

Current Scope

The repositories currently contain implementation code for:

• RISC-V instruction execution and ELF loading in the kernel.
• Linux userland syscall, filesystem, process, thread, signal, pipe, socket, and time-related modules in the kernel.
• Runtime worker orchestration, process lifecycle handling, file snapshots, SharedArrayBuffer page cache support, network bridge interfaces, and diagnostic surfaces.
• SDK helpers for creating a runtime, adding files, running commands, resolving package providers, and attaching a simple terminal.

For a deeper description, start with Architecture.

License

The kernel, runtime, and SDK repositories are licensed under Apache-2.0.