## Summary
- Heuristic and `--safe-rendering` now set
`WEBKIT_DMABUF_RENDERER_FORCE_SHM=1` instead of
`WEBKIT_DISABLE_DMABUF_RENDERER=1`
- Legacy `DISABLE_DMABUF` stays owned so operators can still set
`=0`/`=1` and take over the decision
- Linux troubleshooting docs updated to match (#3654)
## Test plan
- [ ] unit tests in `webkit_rendering::tests`
- [ ] On NVIDIA + WebKitGTK 2.52: workspace switch no longer SIGSEGVs
where the distro NVIDIA guard does not fire (Debian/Ubuntu
proprietary-NVIDIA may still crash — #3654 stays open for that path)
- [ ] `WEBKIT_DISABLE_DMABUF_RENDERER=0` still stands the heuristic down
---------
Signed-off-by: Taksh <takshkothari09@gmail.com>
Signed-off-by: Will Pfleger <pfleger.will@gmail.com>
Co-authored-by: Alia <d32955ad69077062930cc46cfe2df30ca9aaf6f8e76422681265e9e9af704d78@buzz.block.builderlab.xyz>
Co-authored-by: Will Pfleger <pfleger.will@gmail.com>
On some Linux GPU/driver/compositor combinations, WebKitGTK's dmabuf
renderer aborts the web process during startup, so Buzz comes up with no
window at all and the user has no way to fix it. Setting
`WEBKIT_DISABLE_DMABUF_RENDERER=1` avoids the abort by falling back to
the shared-memory buffer path.
WebKit reads each of its rendering variables exactly once per process,
so the choice has to be made before anything initializes — there is no
runtime toggle and no second chance later in the same process. This
decides up front from two cheap preflight signals rather than reacting
to a crash:
- **NVIDIA GPU** — any DRM device under `/sys/class/drm` reporting PCI
vendor `0x10de`, the driver family behind most upstream reports.
- **AppImage** — the `APPIMAGE` environment variable. linuxdeploy's
AppRun hook pins `GDK_BACKEND=x11`, and the dmabuf renderer buys nothing
on that XWayland path.
Either signal disables the dmabuf renderer. Neither signal leaves the
environment untouched.
## Escape hatches
`--safe-rendering` forces the safest configuration for one launch —
`WEBKIT_DISABLE_DMABUF_RENDERER` plus `WEBKIT_DISABLE_COMPOSITING_MODE`
— for a machine neither signal recognises.
Any user assignment of a variable this module may set stands the
heuristic down **wholesale**. Presence is the test, not truthiness, so
`VAR=0` and `VAR=` both count: a user asking for the dmabuf renderer
*on* gets it, even on a machine the heuristic would have opted out.
`--safe-rendering` against such an assignment is refused with a
diagnostic naming both the assignment and the key to unset, and exits
non-zero — the flag and the environment are two incompatible answers to
one question, and neither is guessed.
## Placement
`webkit_rendering::apply()` runs at the top of `fn main()`, before
`buzz_lib::run()`. That is the only point where the process is still
single threaded with no GTK object alive, which is what makes
`std::env::set_var` sound; the module doc and the call site both say so.
The whole module is `#[cfg(target_os = "linux")]` — macOS and Windows
compile none of it.
The decision is a pure function of argv, an injected environment lookup,
and an injected DRM root, so all of it is unit-testable without mutating
the process environment.
Closes#2338. Upstream:
[tauri#9394](https://github.com/tauri-apps/tauri/issues/9394). Same
approach and same variable as
[clash-verge-rev](https://github.com/clash-verge-rev/clash-verge-rev/blob/main/src-tauri/src/utils/linux/workarounds.rs)
`workarounds.rs` and
[screenpipe](https://github.com/screenpipe/screenpipe/blob/main/apps/screenpipe-app-tauri/src-tauri/src/linux_webkit_env.rs)
`linux_webkit_env.rs`.
Signed-off-by: Will Pfleger <pfleger.will@gmail.com>
