VOGONS


First post, by Doctor1th

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Just wondering if there was any benefit to getting a real soundblaster 16 or vodoo 2 card and passing it through to a qemu machine via a PCI Express to PCI bridge? I know with running PowerPC Mac OS in qemu having a real Rage 128 Ultra with such a bridge to pass it through provides 3d hardware acceleration, which currently there is no software emulation for yet. So I might invest in that and was wondering if I may as well grab extra bridge adapters for dos/windows 98 hardware or if that won't make much of a difference.

Reply 1 of 1, by javispedro1

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Remember it's going to be a PCI Sound Blaster 16, which already doesn't have stellar compatibility with DOS games, and no OPL chip, so it's probably not worth the effort.

At least you don't have to worry about passing through the "classic" ISA SB16 IO ranges (22xh, DMA channels, IRQ) because, at least on DOS, the way people used an PCI SB16 is already by trying to emulate an ISA SB16 (i.e. that's what the DOS driver would do).
Though even if such driver works under qemu (already a big if),
it is unlikely the entire thing will work at all, because basically your host system needs to support the barrage of features required for the ISA SoundBlaster emulation to work, including subtractive decoding, DDMA, SERR->NMI propagation, etc.
See Is there PCI-E soundcard with working DOS SB driver? Longshot, but.. DDMA and PCPCI for Low IQ Individuals (Me included) (disclaimer: I also consider myself unfamiliar with the topic and cannot advise on the accuracy of the information...).
And all of this through the guest's emulated PCI bus, then the hosts PCI express bus, then the PCI <-> PCI express bridge...

Considering there were problems getting all of this to dance even on more recent chipsets that were still PCI...
I am rather curious to see if it will work, but it seems Highly Unlikely (TM).
It'll likely work under Windows though with its native drivers, and then on DOS boxes inside Windows using the WDM drivers at least, but I wouldn't know if it would really be an improvement over the qemu emulated sb16.

As for the Voodoo, I have absolutely no idea, but I think it's slightly more likely, seeing it wouldn't need any of the ISA ranges (it doesn't even have VGA, iirc). So it really is just a "simple PCI device". But you then would have to connect it to another VGA card that you would then need to pass through, so again it's probably too much effort...