One VBA-M instance can link to Dolphin. But two won't.

[Magic815]

Hi there,

So I'm having some trouble linking two instances of VBA-M to Dolphin. I'm using the latest VBA-M v2.0.0 Beta 1. And I have almost the latest Dolphin Dev build (4.0-7461). I'm running Windows 8.1, 64 bit. i7 4770k, GTX 770, 32 GB of RAM.

I believe I've followed all the correct instructions on the VBA-M side, but have found that while one instance of VBA-M can link to Dolphin, two don't seem to be able to.

I've run the following tests:

- Port 1 in Dolphin set to GBA, Port 2 set to None.

• Result: VBA-M instance 1 links to Port 1. VBA-M instance 2 doesn't link (this is expected).
  

- Port 1 in Dolphin set to None, Port 2 set to GBA.

• Result: VBA-M instance 1 links to Port 2. VBA-M instance 2 doesn't link (this is expected).
  

- Port 1 in Dolphin set to GBA, Port 2 set to GBA.

• Result: VBA-M instance 1 links to Port 1. VBA-M instance 2 doesn't link to Port 2. (this is the problem I'm having).
  

I've triple checked all my settings in VBA-M and even made a forum post over there to get help from their developers. So far, we haven't been able to solve it yet and they suggested that it might be an issue with Dolphin.

Any thoughts? Is anyone else experiencing this issue?

[Magic815]

We cracked it! So the game is question was Legend of Zelda: Four Swords, and the issue was that I had the audio set to DSP HLE.

Once I changed it to DSP LLE recompiler (and used real DSP ROM dumps - not the ones reverse engineered into Dolphin), both VBA-M instances linked up.

So I guess does this become a bug report for use of HLE with LoZ: Four Swords? It looks like it's incompatible with GBA linking multiple instances.

[OatmealDome]

Since Zelda ucode HLE recently went under a complete overhaul, I guess this is an issue with the rewrite (and thus it lands in delroth's territory). You could try using a build before 4.0-7226 (which is before the rewrite was merged) and see if you can reproduce it there. However, we don't have a bug tracker (Google Code went read-only because it's shutting down soon), so there's nowhere to formally report this bug yet.

[JMC47]

Considering AX-HLE suffers from the same bug in Crystal Chronicles (AX-UCode), I dunno if we can really pin the problem on the rewrite. HLE obviously has problems with multiple GBAs, and may have been working by luck before in this one game. Tetra's Trackers in Japanese FSA didn't work with multiple GBAs in old Zelda-HLE as well.