jack2: issues w. 32bit clients in 64bit jackd since Fedora 22

Hi all.

After upgrading to fc22 during summer, I'm having issues with 32bit jack
clients running in my 64bit jackd.

I'd be thankful for any clues to what's going on, and ways to debug
this.  And if others would care to check, and confirm/disprove the same
behavior, please tell me what you get.

Here's what happens:

The 32bit clients connect well, but the callbacks never seem to return,
making jackd send out a steady stream of xruns and errors:

JackEngine::XRun: client = simple_client was not finished, state = Triggered

I'm checking with jack2 installed (jack-1.9.10), with .i686 and .x86_64
versions installed using the standard fedora packages.

The same 32bit clients work well in fc21, fc20, and ubuntu 14.04 (in a
vm on the same hardware).  Afaik, nothing has changed vs. the -mixed
flag in jackd, and would expect 32bit clients to run well inside a 64bit
jackd.

Checking with example-clients/simple-client.c from the jack sources:

$ gcc -m32 -g -O -lm -ljack simple_client.c -o simple_client
 $ ./simple_client

- results in the noted behavior.  Without -m32 everything's fine.

Thanks,

-anders