No working audio with the homebrew game Super Mario 64.

[Bruceleeto]

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Platform / OS / Hardware: Linux / PC

Flycast version: v2.5-1-g90ed30f70

Posting on behalf of someone else.

Description of issue: audio not working
Reason: Limited MMU support.

https://github.com/jnmartin84/sm64-dc/blob/main/src/pc/audio/dc_audio_kos.c

Debugging Steps Tested
None, just posting on behalf of someone else and the reason audio doesnt work seems clear. The repo shown above provides a easy to use cdi builder to verify.

[Bruceleeto]

What the code does
Installing "unified TLB mappings" to do a wraparound circular buffer
using 8 entries for the left channel of audio, 8 entries for the right channel of audio, each entry a 4kb mapping, to linearly duplicate the same 16kb buffer of physical memory for each channel over a 32kb virtual memory window for each channel
cacheable read/write mappings
can see Section 3 Memory Management Unit (MMU) of sh4 manual

[Bruceleeto]

Adding some more info for reference.

Known homebrew games that use the MMU.
Bloom PSX Emulator https://github.com/pcercuei/bloom
Mario 64 https://github.com/jnmartin84/sm64-dc
Starfox 64 https://github.com/jnmartin84/sf64-dc

And Bleem but unclear how it uses the MMU.

I removed the wince check
Bruceleeto@59b64c3#diff-50a72dabb36bafeef2dbde1c7d4ba26897a0b1feff98a63342c86e76dc39ecbeR72-R436

i think I fucked up with UTLB_Sync but doesnt matter just for testing.

2025-12-29_00-25-28.mp4

https://www.youtube.com/watch?v=FvVXBLDw4Ak

With the check removed mario 64 audio works but some visual glitches occur unclear if that's related to the MMU change.
With Bloom games can run but other slow / crash / freezes.
With Starfox 64 game works but freezes after about 30 secs not disimilar to Bloom.
Not yet tested Mario kart.

link to the discord convo.
https://discord.com/channels/627187835945877505/627187836441067533/1454941864431194225

note: starfox has a WDT 'emulator check' so with the MMU change alone the game will crash.

[flyinghead]

Sadly after following the "easy" cdi builder instructions, and trying various kos branches, all I get is this:

[flyinghead]

It looks like full MMU isn't needed and the common "store queue only" MMU mode could work fine.
The only exception is at start up when the sound buffers are initialized, between these two messages:
snd_init(): loading 3272 bytes into SPU RAM and Dreamcast Audio: Initialized. 26800 Hz, ring buffer size: 16384 bytes per channel.
In this interval, the MMU is used with regular memory accesses. After that, only store queues are to write to them, which is supported without enabling full MMU support.

I can't build the game locally so I'm limited in the experiments I can do on the game side.
I did a quick test of enabling the MMU just for the audio initialization and audio seems to be fine afterwards.

[Bruceleeto]

Cool.
It should build fine with kos v2.2.1.
On the visual glitches I mentioned that was nothing just forgot to set to per pixel sorting.
and the environ.sh it uses https://github.com/jnmartin84/sm64-dc/blob/main/environ.sh

[flyinghead]

Unfortunately my test wasn't correct, and the full mmu is needed.
So I pushed a fix on the dev branch that enables full mmu when it detects the creation of an unexpected (non-store queue) mapping.

[Bruceleeto]

Tested. works for me for mario 64.
So gonna close because
Starfox has a WDT check that works as a 'emulator check' as no emulator bothers with the WDT. So this will fail anyway.
I had a crack at implementing WDT but this is the only game I know that uses it so it is debateable how much it is worth adding.
Bruceleeto@6dd5932

Bloom the PSX emulator. I have yet to test and I will open a new issue if a MMU related fault occurs with it when I test.