mirror of
https://github.com/marcoallegretti/WEFT_OS.git
synced 2026-03-27 01:13:09 +00:00
Marco Allegretti
3ee2f283d8
Wire ShellClient into App so its Wayland event queue is dispatched each frame via about_to_wait. This ensures configure, focus_changed, and window_closed events from the compositor are processed. window_closed now triggers a clean Servo shutdown. The EGL rendering path (WindowRenderingContext + surfman eglSwapBuffers) produces frames transparently via Mesa DMA-BUF buffer sharing; no explicit zwp_linux_dmabuf_v1 code is required in the shell. Remaining: ZweftShellWindowV1 is created with surface=null; sharing the winit wl_surface with the shell client connection is not currently feasible without refactoring to a single shared Wayland connection.
140 lines
6.4 KiB
Markdown
140 lines
6.4 KiB
Markdown
# Servo Pin
|
||
|
||
## Current pin
|
||
|
||
| Field | Value |
|
||
|---------|------------------------------------------------------------------------------------|
|
||
| Source | <https://github.com/marcoallegretti/servo> (fork of servo/servo) |
|
||
| Branch | `servo-weft` |
|
||
| Rev | `04ca254f843ed650d3e5b14e5693ad51a60cc84b` (servo-weft tip, 2026-03-11) |
|
||
| Crate | `servo` (package name as of 2026-03-11; previously `libservo`) |
|
||
| Feature | `servo-embed` (optional; off by default) |
|
||
|
||
## Adding the Cargo dependencies
|
||
|
||
The Servo deps are **not** in `Cargo.toml` by default to avoid pulling the
|
||
Servo monorepo (~1 GB) into every `cargo check` cycle. To activate, add the
|
||
following to `crates/weft-servo-shell/Cargo.toml` and change the `servo-embed`
|
||
feature line to declare `dep:servo`, `dep:winit`, and `dep:softbuffer`:
|
||
|
||
```toml
|
||
[features]
|
||
servo-embed = ["dep:servo", "dep:winit", "dep:softbuffer"]
|
||
|
||
[dependencies.servo]
|
||
git = "https://github.com/marcoallegretti/servo"
|
||
branch = "servo-weft"
|
||
optional = true
|
||
default-features = false
|
||
|
||
[dependencies.winit]
|
||
version = "0.30"
|
||
optional = true
|
||
features = ["wayland"]
|
||
|
||
[dependencies.softbuffer]
|
||
version = "0.4"
|
||
optional = true
|
||
```
|
||
|
||
Then build:
|
||
|
||
```sh
|
||
cargo build -p weft-servo-shell --features servo-embed
|
||
```
|
||
|
||
The first build downloads and compiles Servo and its dependencies, which takes
|
||
30–60 minutes cold. Subsequent incremental builds are faster.
|
||
|
||
## System dependencies
|
||
|
||
The following system packages are required when `servo-embed` is enabled:
|
||
|
||
- `libgles2-mesa-dev` or equivalent OpenGL ES headers
|
||
- `libssl-dev`
|
||
- `libdbus-1-dev`
|
||
- `libudev-dev`
|
||
- `libxkbcommon-dev`
|
||
- `libwayland-dev`
|
||
|
||
On Fedora/RHEL: `mesa-libGL-devel openssl-devel dbus-devel systemd-devel libxkbcommon-devel wayland-devel`
|
||
|
||
## Rendering approach
|
||
|
||
Default: `SoftwareRenderingContext` (CPU rasterisation) blitted to a
|
||
`softbuffer`-backed winit window.
|
||
|
||
EGL path: set `WEFT_EGL_RENDERING=1` at runtime. The embedder attempts
|
||
`WindowRenderingContext::new` using the winit display and window handles.
|
||
If construction fails it falls back to software automatically.
|
||
When the EGL path is active Servo presents directly to the EGL surface via
|
||
surfman's `eglSwapBuffers`; the softbuffer blit is skipped. Mesa handles
|
||
DMA-BUF buffer sharing with the compositor transparently.
|
||
|
||
## Known gaps at this pin
|
||
|
||
- **GAP-1**: ~~Wayland input events not forwarded to Servo~~ **Resolved** — keyboard and
|
||
mouse events forwarded via `webview.notify_input_event`; key mapping in `keyutils.rs`.
|
||
- **GAP-2**: EGL `WindowRenderingContext` path scaffolded (`WEFT_EGL_RENDERING=1`).
|
||
When EGL is active, Servo presents frames via surfman's `eglSwapBuffers`; Mesa handles
|
||
DMA-BUF buffer sharing with the compositor transparently — no explicit
|
||
`zwp_linux_dmabuf_v1` code is needed in the shell for basic rendering.
|
||
The `zweft_shell_manager_v1` event queue is now dispatched each frame so `configure`,
|
||
`focus_changed`, and `window_closed` events are processed; `window_closed` triggers a
|
||
clean Servo shutdown.
|
||
Remaining gap: the `ZweftShellWindowV1` is created with `surface = null`; the winit
|
||
`wl_surface` is not yet associated with the shell window slot (requires sharing a single
|
||
Wayland connection between winit and the shell client, which is not currently feasible
|
||
without significant refactoring).
|
||
- **GAP-3**: WebGPU adapter on Mesa may fail CTS — validation task, requires Mesa GPU hardware.
|
||
- **GAP-4**: ~~CSS Grid~~ **Grid resolved** (Taffy-backed, fully wired).
|
||
~~CSS `backdrop-filter` unimplemented~~ **`backdrop-filter` resolved** (servo/servo issue
|
||
[#41567](https://github.com/servo/servo/issues/41567)). Implemented across two commits:
|
||
- `marcoallegretti/stylo` `servo-weft` `f1ba496`: removed `servo_pref = "layout.unimplemented"`
|
||
from `backdrop-filter` in `style/properties/longhands.toml` (enables parsing).
|
||
- `marcoallegretti/servo` `servo-weft` `8e7dc40`: `Cargo.toml` patched to use the stylo fork;
|
||
`style_ext.rs` adds `backdrop-filter` to `establishes_stacking_context` and
|
||
`establishes_containing_block_for_all_descendants`; `stacking_context.rs` guards the
|
||
WebRender stacking-context early-return on `backdrop_filter.0.is_empty()`; `display_list/mod.rs`
|
||
adds `BuilderForBoxFragment::build_backdrop_filter` calling `push_backdrop_filter` before
|
||
background paint.
|
||
- **GAP-5**: Per-app process isolation — requires Servo multi-process (constellation) architecture.
|
||
|
||
## Update policy
|
||
|
||
The `servo-weft` branch is the working branch for WEFT-specific Servo patches.
|
||
Upstream servo/servo changes are merged into it periodically.
|
||
|
||
To rebase onto a new upstream commit:
|
||
|
||
1. In the `marcoallegretti/servo` repo: `git fetch upstream && git rebase upstream/main` on `servo-weft`.
|
||
2. Force-push `servo-weft`.
|
||
3. Update `Rev` in this file to the new tip SHA.
|
||
4. Run `cargo update -p servo` in the WEFT OS workspace.
|
||
5. Confirm the compositor and shell tests still pass.
|
||
|
||
To submit patches upstream: open a PR from `servo-weft` (or a topic branch) to `servo/servo`.
|
||
|
||
## Stylo fork
|
||
|
||
The Stylo CSS engine is a separate repo (`servo/stylo`) pinned at rev `dca3934667dae76c49bb579b268c5eb142d09c6a`
|
||
in `Cargo.toml`. To patch it for WEFT-specific changes (e.g. enabling `backdrop-filter`):
|
||
|
||
1. Fork `servo/stylo` to `marcoallegretti/stylo`, create branch `servo-weft`.
|
||
2. Make changes on that branch.
|
||
3. Add to this fork's `Cargo.toml` workspace `[patch]` section:
|
||
|
||
```toml
|
||
[patch."https://github.com/servo/stylo"]
|
||
stylo = { git = "https://github.com/marcoallegretti/stylo", branch = "servo-weft" }
|
||
stylo_atoms = { git = "https://github.com/marcoallegretti/stylo", branch = "servo-weft" }
|
||
stylo_dom = { git = "https://github.com/marcoallegretti/stylo", branch = "servo-weft" }
|
||
stylo_malloc_size_of = { git = "https://github.com/marcoallegretti/stylo", branch = "servo-weft" }
|
||
stylo_static_prefs = { git = "https://github.com/marcoallegretti/stylo", branch = "servo-weft" }
|
||
stylo_traits = { git = "https://github.com/marcoallegretti/stylo", branch = "servo-weft" }
|
||
selectors = { git = "https://github.com/marcoallegretti/stylo", branch = "servo-weft" }
|
||
servo_arc = { git = "https://github.com/marcoallegretti/stylo", branch = "servo-weft" }
|
||
```
|
||
|
||
4. Run `cargo update` to resolve the new stylo deps.
|
||
5. Commit both the `Cargo.toml` and `Cargo.lock` changes to `servo-weft`.
|