[Qemu-devel] Re: no sound in MusicPal with qemu 0.12.2

[malc]

On Sat, 23 Jan 2010, Jan Kiszka wrote:

> Jan Kiszka wrote:
> > malc wrote:
> >> On Sat, 23 Jan 2010, ondrej drbohlav wrote:
> >>
> >>> Hi there,
> >>>
> >>> I have compiled qemu 0.12.2 on an x64 ubuntu (8.10) and run MusicPal
> >>> in it with SDL.
> >>> MusicPal works OK but there is no sound.
> >> Confirmed.
> >>
> >>> I have done essentially the same with qemu 0.11.1. The sound is there
> >>> (thanks jki for suggesting a previous version).
> >>>
> >>> Please find below the configs and logs & contact me if additional info
> >>> is needed.
> >>>
> >>> Cheers, Ondrej
> >>>
> >>> 1) qemu-0.12.2
> >> [..snip..]
> >>
> >> Someone would have to bisect it.
> > 
> > Already done: it's b3a219883ebe21f55a8ee5e7e5b38b9eb309e9c0. But that
> > patch looks sane. I guess it just revealed a hidden bug in Musicpal's
> > i2c use. Need to dig deeper.
> 
> Found, trivial patch on the way.

Will test...

> 
> > 
> >> BTW, Jan, 2e87c5b937444c1155073f7b10d630e0e383e5d8 doesn't quite do
> >> what i said helps[1] and conseqently musicpal enters an infinite loop
> >> again...
> >>
> >> [1] http://lists.gnu.org/archive/html/qemu-devel/2009-09/msg00920.html
> >>
> > 
> > OK, I will have to look into the Linux driver code to check the loop
> > termination conditions again.
> 
> This still makes no sense, at least based on available driver sources
> and so far observed behavior with existing firmware images: the TX queue
> is always setup to form a ring, at no point the driver destroys this
> ring before triggering a TX. So we are only left with a potentially
> undefined (NULL) ring entry pointer, and that is what my commit tried to
> catch. I rather suspect we see a subtle memory corruption here.
> 
> Malc, when do you get this? Could you instrument the loop to check if we
> get off-track before, scanning random guest memory?

I asked some questions before[1] but nobody answered them.. Anyhow i'm
happy to do stuff, just need to be instructed what is this stuff that
needs to be done..

[1] http://lists.gnu.org/archive/html/qemu-devel/2009-10/msg00292.html

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