SIO2MAN Compatibility

SIO2MAN hook compatibility

VMC and controller emulation keep independent original callbacks for the v1 and v2 SIO2MAN export layouts. The SDK driver is embedded when MX4SIO, VMC or PADEMU needs it, and loaded before the block driver and emulation hooks.

MMCE games are the exception: they never get the SDK driver. The in-game MMCE driver (mmcedrv, stock ps2-mmce v2.1.1) takes an SIO2 lock that only the game's own SIO2MAN releases. With the SDK SIO2MAN loaded first, the lock is never released and the game hangs on a black screen after the PS2 logo. Confirmed on hardware with the builds either side of #962 (2ee8292c boots, ad43082f hangs). On MMCE, VMC and PADEMU hook the game's own SIO2MAN when it registers, as they did before #962. test_mmce_sio2man_pack.py checks this. Existing module IDs are preserved. Game libraries registered later use the same version-aware hook installation.

When SDK export entries alias the same original function, the hooks update every alias and retain the actual original callback rather than chaining a hook back into itself. Installing the same hook twice leaves its saved originals intact. The MX4SIO block driver still requires a successful SIO2MAN load.

Adapted from Julian Uy's official OPL PR #1785, commits e87ba6898eda6531196da6201a23676cbf60c92d and 7af5fdbed6d8a7927a99b839de10f4df78c074a3, with repeated-installation protection and version-matched transfer initialization for this fork.

The host regression compiles production installation, alias replacement and wrapper functions for VMC and PADEMU. It checks simultaneous v1/v2 tables, original callback dispatch, aliased entries, replacement tables, repeated installation and missing entries. Linux CI uses ASan/UBSan. Target builds and these host tests do not establish console compatibility: VMC saves/loads, controller emulation and MX4SIO must still be exercised on hardware, including games that replace SIO2MAN after launch.

VMC keeps the calling version through its emulation callback so it releases and reacquires the corresponding SIO2MAN transfer lock. The direct MC2 DMA path captures the version established by the transfer initializer when its input request begins. A competing transfer while VMC releases SIO2 cannot change the callback chosen for the original request.

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Source: docs/SIO2MAN-COMPATIBILITY.md @ 0bc2352133d2.