TI-99/4A: mame_libretro core crashes (SIGSEGV) at launch on scarab 20260511 (ARM/A133P) — core defect, not config

[agiacalone]

Knulli build version

scarab 2026/05/11

Architecture

TrimUI Brick Hammer (Allwinner A133P, aarch64)

Issue

Launching any TI-99/4A (ti99) title crashes the emulator (emulatorlauncher returns status -11 / SIGSEGV) within ~0.5 s, before anything renders, using the modern mame_libretro core (RA 1.22.2).

This is a core-build defect, not configuration or content:

• Not the command. configgen previously emitted an invalid slot option (-ioport:peb:slot3 speech); even after correcting it to -ioport speechsyn (cmdfile verified, fresh .pyc), the stock core still SIGSEGVs. The config fix is in a separate PR; this issue is the remaining crash.
• Not BIOS/content. ti99_4a.zip + ti99_speech.zip present and md5-correct; the same .rpk loads in standalone MAME 0.288.
• A working core runs it fine. Swapping in the libretro buildbot mame_libretro (MAME 0.287, aarch64) with the identical command and content → boots, speech synth initializes, fully playable. So the regression is specifically in the scarab-built mame_libretro for ti99_4a on ARM.

Reproduction

1. Place TI-99 .rpk carts in /userdata/roms/ti99/ and ti99_4a.zip (+ ti99_speech.zip) in /userdata/bios/.
2. Launch any title from EmulationStation.
3. Emulator exits to the menu after ~0.5 s; es_launch_stdout.log shows Exiting configgen with status -11.

Notes / likely related

• Appears to be the same family as MAME 2010 (MAME 0.139) RetroArch Core crashes at launch #81 (MAME 2010 / 0.139 core crashes at launch on this build) — i.e. a broader MAME libretro core regression on these ARM targets in scarab 20260511.
• A Knulli-rebuilt/updated MAME core would also resolve a slight slowness + scratchy audio seen with the generic 0.287 buildbot core on the A133P.
• No gdb/debug symbols on the device image; the kernel logged fatal signal 11 but doesn't symbolize userspace, so no backtrace was obtainable on-device. Happy to capture more with a debug core build.