[Vm-dev] Pulse audio Scratch plugin causes seg fault on 64bit Ubuntu installation

Amos Blanton amos at scratch.mit.edu
Fri Aug 3 01:57:56 UTC 2012


Thanks for looking into this, Dave!
more below...
On Thu, Aug 2, 2012 at 8:12 PM, David T. Lewis <lewis at mail.msen.com> wrote:

>
> For clarification: This VM is compiled from sources on an Ubuntu system
> (as opposed to downloading compiled binaries from e.g squeakvm.org), is
> that correct? If so, is it compiled in normal 64-bit mode, or is it
> compiled in 32-bit mode ( -m32 compiler flag)?
>

Great question! I'm afraid I do not know the answer.

>From looking at this:
http://packages.ubuntu.com/source/precise/squeak-vm

I suspect that the package is probably built in normal 64 bit mode, but I'm
not sure where I'd find the build logs for the binary to confirm that.  I
can't be certain that the files are identical, but I believe we had used a
binary plugin built from the same source in a previous version of the
Scratch package. When we forced installation of that 32 bit package (and
plugin) on 64 bit systems, pulse audio playback and recording worked well.

I just tried replacing the plugin on my system with the 32 bit plugin
downloaded from the ubuntu squeak package, to see if it'd work. Scratch
wouldn't start, and I got the following error:

/usr/lib/squeak/4.4.7-2357//so.vm-sound-pulse: wrong ELF class: ELFCLASS32
could not find module vm-sound-pulse




>
> On Thu, Aug 02, 2012 at 05:36:42PM -0400, Amos Blanton wrote:
> >
> > To reproduce:
> >
> > 1. Execute Scratch using current VM and pulse plugin (on Ubuntu 12.04, 64
> > bit system):
> > Executing: /usr/lib/squeak/4.4.7-2357/squeakvm -encoding UTF-8
> > -vm-display-x11 -xshm -plugins
> > /usr/lib/scratch/plugins/:/usr/lib/squeak/4.4.7-2357/ -vm-sound-pulse
> > /usr/share/scratch/Scratch.image
> > (There is no pulse plugin in /usr/lib/scratch/plugins in my installation
> > package, so it must be using the one in /usr/lib/squeak/4.4.7-2357)
> >
> > 2. Click "Sounds" tab, click play icon next to meow. That results in:
> >
> > Segmentation fault
> >
> > 10273532 [] in SoundPlayer class>playLoop
> > 10262332 Semaphore>critical:
> > 10262240 SoundPlayer class>playLoop
> > 10273228 [] in SoundPlayer
> class>startPlayerProcessBufferSize:rate:stereo:
> > 10273320 [] in BlockContext>newProcess
> > Aborted (core dumped)
> >
> > Note that the same package on 32 bit systems does not produce the error
> > (playback and recording both work).
> >
> > The issue is also described here:
> > https://bugs.launchpad.net/ubuntu/+source/squeak-vm/+bug/1009080
> >
> > If someone can take a look and patch this, we'd very much appreciate it!
> > This is the last major (known) issue we've got with Scratch running on
> > Ubuntu.
> >
> > -Amos
>
>
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