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fix: run Hyprland and COSMIC on hybrid NVIDIA hosts and stop leaking Weston - #155
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…Weston On a host with Intel and NVIDIA GPUs, Hyprland's private KWin renderer opened the NVIDIA render node, whose GBM cannot allocate Hyprland's buffers, so the output never got a mode. That renderer now runs in a bubblewrap namespace that exposes only the other GPU's render node. Single-vendor hosts are unchanged. COSMIC's software-rendered Weston parent, compositor and XWayland now load only Mesa's EGL vendor; NVIDIA's EGL made XWayland crash at startup. COSMIC's Weston parent outlived a failed start or a killed daemon: bwrap's --die-with-parent does not stop the sandboxed process without a PID namespace. The parent now gets one, and shutdown signals its whole process group.
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Self-review at 57f2111. Scope is limited to the Hyprland parent renderer and the COSMIC parent/compositor/XWayland. The node filter only applies when an accessible NVIDIA render node and another accessible render node both exist; otherwise the command is unchanged. The Mesa vendor pin is skipped when Mesa's vendor file is missing. --unshare-pid is added only to the Weston parent; cosmic-comp keeps the host PID view it needs for client credentials and exits with its guard socket. Shutdown now matches the group-signal pattern used by Hyprland and the private session. Validation is listed in the PR body. |
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COSMIC startup failure can leave shutdown signalling an unreserved process-group ID, risking termination of unrelated host processes.
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Revuto completed the review and found no evidence-backed concerns.
Hyprland and COSMIC failed to start on a laptop with Intel and NVIDIA GPUs. COSMIC also left its Weston parent running after a failed start or a killed daemon.
/dev/dri. Single-vendor hosts are unchanged.libnvidia-egl-gbm. The Weston parent, cosmic-comp and XWayland now load only Mesa's EGL vendor when its file exists.--die-with-parentdoes not stop the sandboxed process without a PID namespace (checked on kernel 7.0: SIGTERM and SIGKILL of bwrap both leave it running). The Weston parent now gets--unshare-pid, and shutdown signals its process group. The leaked Weston also kept the host GPU lock descriptor.Validation on the hybrid host (Intel + RTX 5090):
Note
Medium Risk
Touches compositor spawn/teardown, bubblewrap sandboxes, and DRM/EGL vendor selection on session start and shutdown; wrong GPU or signal handling could break workspaces or leave orphan processes.
Overview
Fixes Hyprland and COSMIC on hybrid Intel/NVIDIA laptops and stops COSMIC’s Weston parent from surviving daemon crashes.
Hyprland: When both NVIDIA and another GPU are present, the private KWin virtual renderer now runs under bubblewrap with
/dev/drilimited to the non-NVIDIA render node, so buffer allocation does not land on NVIDIA GBM (which cannot satisfy Hyprland). Single-GPU-vendor hosts are unchanged; bwrap becomes required on hybrid NVIDIA setups.COSMIC: Shared
use_mesa_eglsets__EGL_VENDOR_LIBRARY_FILENAMESto Mesa’s vendor file (when installed) for the Weston parent, cosmic-comp, and authenticated XWayland, avoiding glvnd picking NVIDIA EGL. The Weston bwrap sandbox adds--unshare-pidso--die-with-parentactually tears down Weston; startup/shutdown useunreaped_exitand process-group SIGTERM/SIGKILL so leaked Weston and GPU locks do not persist after a killed daemon.Reviewed by Cursor Bugbot for commit fe7ca98. Configure here.