fix(linux): disable WebKitGTK compositing in VMs to fix black iframes#441
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fix(linux): disable WebKitGTK compositing in VMs to fix black iframes#441
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WebKitGTK promotes iframes, <video>, and canvas elements to GPU-textured compositing layers. In VMs (Apple Virtualization.framework, QEMU, VMware, etc.) the virtio-gpu driver often only supports 2D or limited GL, so GBM buffer allocation for compositing layers fails silently — rendering iframe/video content as black while the main page works fine. Detect VM environments via /proc/cpuinfo hypervisor flag and sys_vendor strings, then set WEBKIT_DISABLE_COMPOSITING_MODE=1 and LIBGL_ALWAYS_SOFTWARE=1 to force software rendering for all content. Native Linux machines with real GPUs are unaffected.
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facusturla
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Feb 27, 2026
…koala73#441) WebKitGTK promotes iframes, <video>, and canvas elements to GPU-textured compositing layers. In VMs (Apple Virtualization.framework, QEMU, VMware, etc.) the virtio-gpu driver often only supports 2D or limited GL, so GBM buffer allocation for compositing layers fails silently — rendering iframe/video content as black while the main page works fine. Detect VM environments via /proc/cpuinfo hypervisor flag and sys_vendor strings, then set WEBKIT_DISABLE_COMPOSITING_MODE=1 and LIBGL_ALWAYS_SOFTWARE=1 to force software rendering for all content. Native Linux machines with real GPUs are unaffected.
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Summary
/proc/cpuinfohypervisor flag and/sys/class/dmi/id/sys_vendorstringsWEBKIT_DISABLE_COMPOSITING_MODE=1to force software rendering for all content including iframesLIBGL_ALWAYS_SOFTWARE=1to ensure consistent Mesa llvmpipe renderingWhy
WebKitGTK promotes iframes,
<video>, and canvas elements to GPU-textured compositing layers (separate from the main page's software-tiled rendering). In VMs (Apple Virtualization.framework, QEMU/KVM, VMware, etc.) the virtio-gpu driver only supports 2D or limited GL — GBM buffer allocation for these compositing layers fails silently, rendering iframe/video content as black while the main page works fine.This explains why Live News (YouTube), Live Webcams, and other iframe-embedded content shows black boxes while all other panels render correctly.
Test plan
[tauri] VM detected; disabled WebKitGTK accelerated compositingmessage in VMWEBKIT_DISABLE_COMPOSITING_MODE=1 LIBGL_ALWAYS_SOFTWARE=1 ./WorldMonitor.AppImage