AMD GCN Chromium Electron Workaround#

Status: Forward-looking patchset infrastructure. The amd_gcn_chromium.py shared patch module and its companion DynamicPatchset enum entry are planned OCLP-side plumbing added ahead of the PatcherSupportPkg Universal-Binaries payload they depend on. As of April 2026, neither has landed on main.

The Problem#

Chrome 125+ and Electron-based apps (e.g. Discord) exhibit heavy UI glitching and complete freezing on AMD GCN 1.0 (Legacy_GCN_7000) GPUs running macOS Ventura or newer. The root cause is a Metal.framework regression in how Chromium's renderer talks to GCN 1.0 hardware after Apple dropped native support in Ventura. GCN 2 / GCN 3 (Legacy_GCN_8000 / Legacy_GCN_9000) are not affected. 1

Current manual workarounds (documented in issue #1145):

• open /Applications/Google\ Chrome.app --args --use-angle=gl — forces OpenGL rendering.
• open /Applications/Discord.app --args --use-angle=gl — same for Electron apps.
• Disable hardware acceleration per-app.

The planned OCLP fix automates this by merging a patched Metal.framework into the system volume, making the workaround transparent to all Chromium/Electron apps at once. 1

Patchset Architecture#

Shared Patch Module: amd_gcn_chromium.py#

Planned location: opencore_legacy_patcher/sys_patch/patchsets/shared_patches/amd_gcn_chromium.py

This module follows the same pattern as other shared patches (MontereyOpenCL, AMDOpenCL, etc.) and will emit a patchset keyed "AMD GCN Chromium Electron Workaround" with a single MERGE_SYSTEM_VOLUME entry targeting Metal.framework:

"AMD GCN Chromium Electron Workaround": {
    PatchType.MERGE_SYSTEM_VOLUME: {
        "/System/Library/Frameworks": {
            "Metal.framework": DynamicPatchset.AMDGCNChromiumElectronWorkaround
        }
    }
}

The value is a DynamicPatchset enum member — not a plain version string — so the CI/import path never tries to resolve the payload on disk until an actual patching run begins.

Runtime Selection Gate in AMDLegacyGCN#

The AMDLegacyGCN.patches() method is the sole caller of AMDGCNChromium.patches(). 2 It gates inclusion on two conditions:

1. Legacy_GCN_7000 only — checked via _is_gpu_architecture_present([device_probe.AMD.Archs.Legacy_GCN_7000]). GCN 8000/9000 do not receive this patch.
2. Ventura or newer — native_os() already returns True for Monterey and below 3, so patches() returns early on pre-Ventura systems. No additional OS gate is needed.

DynamicPatchset Enum and CI Compatibility#

DynamicPatchset is a StrEnum in patchsets/base.py 4 currently holding only MetallibSupportPkg. The AMD GCN Chromium entry will add:

AMDGCNChromiumElectronWorkaround = "AMD GCN Chromium Electron Workaround"

Using an enum member as the patchset value — instead of a filesystem path — lets HardwarePatchsetDetection run in validation=True mode (used by CI) without the Universal-Binaries payload existing yet. 5 In validation mode, present() and native_os() checks are skipped, so every hardware class is iterated; the DynamicPatchset guard prevents _preflight_checks() from stat-ing a non-existent file. 6

Runtime Resolution (_resolve_dynamic_patchset)#

At patch execution time, _preflight_checks() walks the patchset dictionary and replaces any DynamicPatchset value with a concrete path by calling _resolve_dynamic_patchset(variant). 6 For AMDGCNChromiumElectronWorkaround, the resolver will locate the payload root inside PatcherSupportPkg, analogous to how MetallibSupportPkg is resolved today.

PatcherSupportPkg Universal-Binaries Payload Path#

The resolver expects this directory layout within the Universal-Binaries tree:

Universal-Binaries/
  AMD GCN Chromium Electron Workaround/
    System/
      Library/
        Frameworks/
          Metal.framework

The patchset name ("AMD GCN Chromium Electron Workaround") is used as the top-level subdirectory, and the path under it mirrors the MERGE_SYSTEM_VOLUME target /System/Library/Frameworks/Metal.framework.

Key References#