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darling-lol/docs/TROUBLESHOOTING.md
T
lucannez64andClaude Opus 5.5 4370f375cd Cut Darling overhead in League fights and add passive match capture
Game process (ARAM Hexgate: 84 -> 127 FPS average, slowest stretches ~110):
- Local pthread mutexes, condition variables and Mach semaphores are on by
  default in the game process only, with /tmp/rclol-no-local-* opt-outs.
  The main thread's darlingserver waits fell from 1.36 to 0.10 ms per frame.
- Local semaphores: the count and the slot generation change in one
  compare-exchange, a destroy leaves a negative marker, the table is reset
  after fork, and names the table did not create go to the server.
- Metal: drop identical re-binds (keyed on the Indium object, depth-stencil
  retained), pass blit resources by reference, and stop resetting vertex
  descriptors twice.
- Core isolation of the main thread is opt-in (/tmp/rclol-core-isolation);
  it lowered FPS in its only match.
- Optimized libc/libc++/Foundation overlays, AVX2 string primitives, real CPU
  topology and their installers and offline checks.

Tools and docs:
- tools/riot-match-capture: passive /proc sampler, user-space IP profiler and
  reports, plus a comparison against the game's netstats.
- tools/riot-lsem-model and tools/riot-metal-bind-model: host models that
  extract the shipped code and check it.
- tools/install-riot-metal-pair.sh installs Metal and Indium together.
- Status, setup, testing and troubleshooting docs updated with the measured
  matches and the switch table; manifest file counts match the patches.

Co-Authored-By: Claude Opus 5.5 <[email protected]>
2026-10-14 16:48:34 +02:00

8.8 KiB
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Troubleshooting

Use the setup instructions from the repository root as your ordinary user. Exit the game and both clients manually before a full installation or Darling restart. Incremental server/memory installers can replace files without interrupting processes, but their changes need a later full restart to activate.

Memory installer: permission denied

An earlier sudo server installation can create root-owned build/backups. The old memory installer tried to create build/backups/memory-runtime there and failed at backup_folder.mkdir(...). The corrected default is a separate user-owned build/memory-runtime-backups directory:

python3 tools/install-riot-memory-runtime.py

For an explicitly chosen backup location:

python3 tools/install-riot-memory-runtime.py --backup-dir "$HOME/darling-memory-backups"

If the destination library itself is root-owned, inspect the named path and its ownership before retrying with sudo. Do not run all setup/build steps as root or recursively change ownership of the system SDK. Backups and binaries are ignored by Git and must stay local.

Updated library or server still behaves like the old version

Atomic replacement preserves active process mappings. Darling also uses an overlay filesystem; updating its backing prefix from the host can leave an old file visible inside the active namespace. A fresh standalone guest check continued to report the old memory behavior despite the host path having the new checksum. Reopening only Riot does not replace this namespace.

After exiting the game and both clients manually:

darling shutdown
sh scripts/run.sh

Do not run these commands during a match. Use the independent reclamation probe in testing to verify the new guest behavior after activation. An installer result with installed: true and restart_performed: false confirms the disk update, not activation.

Around 5 GB of RAM with just the clients open

The observed proportional resident footprint was roughly 4.3 GiB across Riot, League and Darling, including 50 crash-handler processes. Roughly 3 GiB came from private anonymous mappings/native heaps; graphics mappings accounted for about 238 MiB. Large virtual address reservations are not equivalent to resident RAM, and summed RSS double-counts shared pages. Use proportional set size (PSS), swap and host memory pressure to assess the actual footprint.

The old kernel library returned success for Darwin allocator free/reuse hints without making any pages reclaimable. The replacement maps free/reusable hints to Linux MADV_FREE, and reuse to MADV_POPULATE_WRITE. The standalone 4 MiB buffer becomes reclaimable and returns to normal on reuse while preserving surviving data. This fixes a demonstrated runtime behavior, but does not explain all client allocations or prove a specific RAM reduction. Linux may retain lazily reclaimable pages in RSS while RAM is available. A five-minute idle observation did not show rapid client memory growth.

Build/install the kernel library using the incremental update steps, then perform the manual restart when finished playing. Linux 5.14+ is required. Do not kill client helpers as an attempted memory optimization during play.

Installer exits, cannot write temporary files, or Install appears idle

Use sh scripts/installer.sh euw (or your supported region). The first-time launcher must omit the installed client's --app-root and pass --skip-to-install; the normal wrapper now does this. It also selects league_of_legends so the product installation UI appears after login.

If logs report guest /private/tmp permission errors, the default prefix needs its own temporary directory. The corrected full runtime installer creates it. To repair just this default-prefix directory as your ordinary user:

mkdir -p "$HOME/.darling/private/tmp"
chmod 1777 "$HOME/.darling/private/tmp"

The installer fetcher no longer treats a missing archive Info.plist or the informational unzip | head listing as a fatal download failure. Download and extraction errors still fail. The wrapper invokes this fetcher with Bash, since its pipefail setting is unsupported by some /bin/sh implementations.

There is also a separate known compatibility gap: native LaunchAgent watch registration can return HTTP 409 after the League install path is accepted, leaving the download idle. A historical inspector hook handles this and interrupted pending_verify states in 28 mock cases, but that hook is disabled in normal launches and excluded from the manual workflow. There is no verified runtime-only replacement for that handoff in this snapshot. Do not assume the native permission and launcher fixes resolve every idle Install case, or enable debugger/API automation to work around it.

LaunchServices dereferenced a nullable error-output pointer in six paths. The patch checks the pointer itself and populates supplied outputs; the standalone regression covers missing handlers and null outputs. Electron opens LaunchServices through an absolute CoreServices subframework path, so the paired installer also replaces that binary in the stopped guest prefix. Updating only RuntimeFrameworks/LaunchServices.framework can leave the crash unfixed.

Historical host-browser forwarding depended on an inspector hook and is disabled in normal launches. The native null-pointer fix prevents this demonstrated crash; it does not guarantee that every external link opens on the host or explain every unrelated button crash.

The first dynamically resolved GL call could lose floating-point arguments during ELF symbol lookup. Chromium's linear sampler request then failed and left nearest sampling. The generated resolver now preserves those registers. Install both the rebuilt native libGL.dylib in RuntimeLibraries and the OpenGL framework's library copy using the paired runtime installer; the framework alone is insufficient.

A separate multi-window path stopped the active async presenter when another differently sized surface was drawn in the same context. Such surfaces now use readback without stopping it. Native regressions cover both fixes; user confirmation of the startup splash remains pending. See testing for the first-call sampler and interleaved-window probes.

Build fails on a new compiler or runs out of memory

  • objc4 debug macro mismatch: use the empty build type from scripts/build.sh, rather than Release/NDEBUG.
  • OpenDirectory 32-bit ivar errors: keep TARGET_i386=OFF; the supported client is x86-64.
  • Undefined empty Objective-C collection symbols: retain the patched macOS 10.15 Objective-C runtime code generation.
  • LLVM branch opcode errors: retain the Indium LLVM 22/23 compatibility patch; do not replace its branch handling with an unconditional version-specific opcode.
  • Build process killed: lower parallelism, for example JOBS=2 ./scripts/build.sh or --parallel 1 for an incremental component build.
  • Incremental helper cannot find flags.make or link.txt: use Unix Makefiles, not Ninja.
  • Prebuilt Swift file contains Git LFS pointer text: install Git LFS and fetch the original upstream assets; pointer text is not a usable library.

Lower fight FPS than Windows

The game code itself runs natively under Darling: the x86-64 slice of the universal binary executes unchanged, picks its instruction-set paths with cpuid on the real CPU, and sizes its worker pool from the real logical CPU count. What differs from Windows is the path around it. Every Metal call goes through Objective-C, the Metal wrapper, Indium and Vulkan instead of a native Direct3D driver, and kernel services go through the emulation and darlingserver. In an ARAM fight the game's own code now takes most of a frame; see status for measurements.

If FPS drops back towards the 10-13 morning numbers (75–85 on Hexgate):

  1. Make sure the current kernel library, Metal and Indium overlays are installed and active: exit the game and both clients, then darling shutdown and sh scripts/run.sh (setup).
  2. Check the game's line in /tmp/rclol-game-decisions.log: it should read local_semaphores=1 and core_isolation=0. No /tmp/rclol-no-local-* file should exist unless you created it on purpose.
  3. Capture a match with tools/riot-match-capture/sample-match.py and compare it with an earlier one using compare-matches.py (testing). A server wait above about 0.5 ms per frame means one of the local paths is off. A runqueue wait above a few percent on the main thread means the CPU is oversubscribed, for example by /tmp/rclol-core-isolation or background load.

Compare matches on the same map: Bilgewater runs a few percent below Hexgate.