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SB Live DOS emulation - my fight with SERR# to NMI routing (Developers)

posted by Japheth Homepage, Germany (South), 19.05.2008, 09:55

> So the conclusion is that properly working SERR# to NMI rounting is only a
> partial condition for working SBEMU. I have no any idea what the Hell is in
> DMA :(
I didn't really understand what you did, but since SB digital sound has no relations to NMI, I wonder what you'd expected.

The problem with the DOS SBEMU driver is that it has to "cooperate" with all sorts of "OS" in protected-mode. Trapping DMA port access is no possible strategy, since it is not guaranteed that an IO permission bitmap exists at all. IIRC this software installs Debug breakpoints for in/out access to port 20h and then - inside the exception handler - tries to figure out what the program might want to do. I guess this approach requires a fully compatible legacy DMA controller to be installed.

> BTW Japheth, what about SB Live/AC97 JLM? ;-)
It's still on my todo list. But this won't change the DOS sound problem for protected-mode applications. A proper SB emulation for SB Live/AC 97 requires a HDPMI JLM as well - or, at the very least, that HDPMI installs an IO permission bitmap.

---
MS-DOS forever!

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