On Thu, 28 Oct 2010, Gerd Hoffmann wrote: > Hi, > > > Nice timing there. I wonder how long it took bright folks at redhat to > > code this HDA stuff? > > A bunch of days. Played with the usb-audio patch first. But I suspect > getting timing-sensitive isochronous usb devices emulated reasonable well is > pretty hard due to the latency requirements. And it isn't just the usb > subsytem, all qemu must improve here. Example: enabling the threaded vnc > server improves usb-audio sound quality, you don't get dropouts on every bulky > screen update then.
We (me, Wu Fengguang and Hans Peter Anvin) tried to do something about usb-audio, to no avail. > > But for now I tried HDA route instead. > > > Since yesterday i was contacted by folks who wanted > > to pay money to get VirtualBox's HDA ported to QEMU, and it took me from > > 16:00 today till basically 15 minutes ago to get the sound pumping from > > DOS and Linux.. > > Oh, there is a HDA driver for DOS? /me looks surprised ... DOS doesn't need drivers you know, anyhow: http://mpxplay.sourceforge.net/ > > > Regardless of the answer to my question the NIH is such a nice thing, eh? > > Sure ;) I don't do that just for fun though. I *have* looked at the vbox > driver first. > > The fundamental problem is the qemu world didn't stop at the point where vbox > forked off, and of course in vbox things are changing too. We have alot of > infrastructure for drivers which isn't in vbox, and likewise the other way > around. Most notable difference is qemu's qdev is quite useful to model the > HDA bus. > > So there are basically two options: > > (1) Port the vbox driver to qemu, then to tons of changes and > cleanups to properly integrate into modern qemu. > (2) Start over from scratch. > > I believe in the end it wouldn't have saved work to use the vbox code as > starting point. At the very least their code does work here (on a PPC with DOS and mpxplay) and yours doesn't. I'd have to check things on my x86_64 box to ensure it's not a endianness issue of some sort, otherwise things are hard to explain since mpxplay's hda handling is based on ALSA. -- mailto:av1...@comtv.ru
