mirror of
https://github.com/marcoallegretti/WEFT_OS.git
synced 2026-03-27 01:13:09 +00:00
Marco Allegretti
e3504c324b
- flake.nix, infra/nixos/: NixOS VM with Mesa, virtio-gpu, Wayland, systemd user services for compositor and session supervisor - infra/vm/: QEMU build and run scripts - .github/workflows/ci.yml: add Linux job to type-check weft-servo-shell and weft-app-shell with --features servo-embed - docs/architecture.md, docs/security.md, docs/building.md: replace stale pre-implementation design documents - README.md: rewrite to reflect current codebase - crates/weft-servo-shell/SERVO_PIN.md: update implementation status and add SpiderMonkey process boundary statement
146 lines
6.7 KiB
Markdown
146 lines
6.7 KiB
Markdown
# Servo Pin
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## Current pin
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| Field | Value |
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|---------|------------------------------------------------------------------------------------|
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| Source | <https://github.com/marcoallegretti/servo> (fork of servo/servo) |
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| Branch | `servo-weft` |
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| Rev | `04ca254f843ed650d3e5b14e5693ad51a60cc84b` (servo-weft tip, 2026-03-11) |
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| Crate | `servo` (package name as of 2026-03-11; previously `libservo`) |
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| Feature | `servo-embed` (optional; off by default) |
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## Cargo dependencies
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The Servo deps are wired in `crates/weft-servo-shell/Cargo.toml` and
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`crates/weft-app-shell/Cargo.toml` under the `servo-embed` optional feature.
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They are off by default to avoid pulling the Servo monorepo (~1 GB) into every
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`cargo check` cycle.
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Current `Cargo.toml` block (already committed):
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```toml
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[features]
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servo-embed = ["dep:servo", "dep:winit", "dep:softbuffer"]
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[dependencies.servo]
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git = "https://github.com/marcoallegretti/servo"
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branch = "servo-weft"
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optional = true
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default-features = false
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[dependencies.winit]
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version = "0.30"
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optional = true
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features = ["wayland"]
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[dependencies.softbuffer]
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version = "0.4"
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optional = true
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```
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To build:
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```sh
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cargo build -p weft-servo-shell --features servo-embed
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```
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The first build downloads and compiles Servo and its dependencies, which takes
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30–60 minutes cold. Subsequent incremental builds are faster.
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## System dependencies
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The following system packages are required when `servo-embed` is enabled:
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- `libgles2-mesa-dev` or equivalent OpenGL ES headers
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- `libssl-dev`
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- `libdbus-1-dev`
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- `libudev-dev`
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- `libxkbcommon-dev`
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- `libwayland-dev`
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On Fedora/RHEL: `mesa-libGL-devel openssl-devel dbus-devel systemd-devel libxkbcommon-devel wayland-devel`
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## Rendering approach
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Default: `SoftwareRenderingContext` (CPU rasterisation) blitted to a
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`softbuffer`-backed winit window.
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EGL path: set `WEFT_EGL_RENDERING=1` at runtime. The embedder attempts
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`WindowRenderingContext::new` using the winit display and window handles.
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If construction fails it falls back to software automatically.
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When the EGL path is active Servo presents directly to the EGL surface via
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surfman's `eglSwapBuffers`; the softbuffer blit is skipped. Mesa handles
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DMA-BUF buffer sharing with the compositor transparently.
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## Known gaps at this pin
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- **GAP-1**: ~~Wayland input events not forwarded to Servo~~ **Resolved** — keyboard and
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mouse events forwarded via `webview.notify_input_event`; key mapping in `keyutils.rs`.
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- **GAP-2**: ~~`ZweftShellWindowV1` created with `surface = null`~~ **Resolved** —
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`ShellClient::connect_with_display(display_ptr, surface_ptr)` uses
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`Backend::from_foreign_display` to share winit's `wl_display` connection; the winit
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`wl_surface` pointer is passed directly to `create_window`, associating the compositor
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shell slot with the actual rendered surface. `ShellClient` is now constructed inside
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`resumed()` after the winit window exists, not before the event loop. EGL path and
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per-frame event dispatch are unchanged.
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Protocol note: `wayland-scanner 0.31` generates `_type` (not `r#type`) for the
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`navigation_gesture` event arg named `type`.
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- **GAP-3**: WebGPU adapter on Mesa may fail CTS — validation task, requires Mesa GPU hardware.
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- **GAP-4**: ~~CSS Grid~~ **Grid resolved** (Taffy-backed, fully wired).
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~~CSS `backdrop-filter` unimplemented~~ **`backdrop-filter` resolved** (servo/servo issue
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[#41567](https://github.com/servo/servo/issues/41567)). Implemented across two commits:
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- `marcoallegretti/stylo` `servo-weft` `f1ba496`: removed `servo_pref = "layout.unimplemented"`
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from `backdrop-filter` in `style/properties/longhands.toml` (enables parsing).
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- `marcoallegretti/servo` `servo-weft` `8e7dc40`: `Cargo.toml` patched to use the stylo fork;
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`style_ext.rs` adds `backdrop-filter` to `establishes_stacking_context` and
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`establishes_containing_block_for_all_descendants`; `stacking_context.rs` guards the
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WebRender stacking-context early-return on `backdrop_filter.0.is_empty()`; `display_list/mod.rs`
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adds `BuilderForBoxFragment::build_backdrop_filter` calling `push_backdrop_filter` before
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background paint.
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- **GAP-5**: ~~Per-app process isolation~~ **Resolved** — each app runs in a separate
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`weft-app-shell` and `weft-runtime` OS process pair supervised by `weft-appd`. OS-level
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isolation does not require Servo's multi-process constellation architecture.
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- **GAP-6**: SpiderMonkey is not sandbox-isolated beyond process-level isolation. JIT-compiled JS
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runs with the same memory permissions as the Servo process. WEFT relies on SpiderMonkey's own
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security properties for the JavaScript execution boundary. See `docs/security.md` for the full
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bounded statement. Not addressed.
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## Update policy
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The `servo-weft` branch is the working branch for WEFT-specific Servo patches.
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Upstream servo/servo changes are merged into it periodically.
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To rebase onto a new upstream commit:
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1. In the `marcoallegretti/servo` repo: `git fetch upstream && git rebase upstream/main` on `servo-weft`.
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2. Force-push `servo-weft`.
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3. Update `Rev` in this file to the new tip SHA.
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4. Run `cargo update -p servo` in the WEFT OS workspace.
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5. Confirm the compositor and shell tests still pass.
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To submit patches upstream: open a PR from `servo-weft` (or a topic branch) to `servo/servo`.
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## Stylo fork
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The Stylo CSS engine is a separate repo (`servo/stylo`) pinned at rev `dca3934667dae76c49bb579b268c5eb142d09c6a`
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in `Cargo.toml`. To patch it for WEFT-specific changes (e.g. enabling `backdrop-filter`):
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1. Fork `servo/stylo` to `marcoallegretti/stylo`, create branch `servo-weft`.
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2. Make changes on that branch.
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3. Add to this fork's `Cargo.toml` workspace `[patch]` section:
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```toml
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[patch."https://github.com/servo/stylo"]
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stylo = { git = "https://github.com/marcoallegretti/stylo", branch = "servo-weft" }
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stylo_atoms = { git = "https://github.com/marcoallegretti/stylo", branch = "servo-weft" }
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stylo_dom = { git = "https://github.com/marcoallegretti/stylo", branch = "servo-weft" }
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stylo_malloc_size_of = { git = "https://github.com/marcoallegretti/stylo", branch = "servo-weft" }
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stylo_static_prefs = { git = "https://github.com/marcoallegretti/stylo", branch = "servo-weft" }
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stylo_traits = { git = "https://github.com/marcoallegretti/stylo", branch = "servo-weft" }
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selectors = { git = "https://github.com/marcoallegretti/stylo", branch = "servo-weft" }
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servo_arc = { git = "https://github.com/marcoallegretti/stylo", branch = "servo-weft" }
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```
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1. Run `cargo update` to resolve the new stylo deps.
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2. Commit both the `Cargo.toml` and `Cargo.lock` changes to `servo-weft`.
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