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Will PflegerandGitHub
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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>