linuxaudio.org

Hi David,
On 06/01/2012 03:48 PM, David Adler wrote:

quoted text
> On Fri, Jun 1, 2012 at 2:52 PM, Robin Gareus wrote:

>>

>> It might have to do with Arch's compiler[-flags] and how jack2 uses

>> unions .. or scoping: JackGlobals vs Engine-Parameters.. although I

>> don't have an explanation.. all seems good.

>

> Compiler flags (for 32bit) are, (from unaltered /etc/makepkg.conf):

> CXXFLAGS="-march=i686 -mtune=generic -O2 -pipe -fstack-protector

> --param=ssp-buffer-size=4 -D_FORTIFY_SOURCE=2"

>

>> A hunch: it could be caused by using 'server_ptr->verbose.b' (a union)

>> as boolean. The sever only checks "if (server_ptr->verbose.b)". The

>> union itself comprises other uninitialized values that could make it

>> evaluate to true (though it shouldn't, but maybe some compiler

>> optimization casts it to (int) instead of (bool) )

>>

>>

>> I know this is the '-users' list (I'm ccing jack-devel), but could

>> someone who experiences the problem try to track it down?

>>

>> Basically just add a few printf()'s. Start at: common/JackControlAPI.cpp

>> - line 926 - before the call to  "new JackServer(..)" add

>>

>>  printf("DEBUG verbose: %s\n",(server_ptr->verbose.b)?"on":"off");

>>

>> recompile, launch jackd. If it prints "verbose: on", sth is wrong with

>> parameter initialization in main() or with using unions. If it's "off"

>> the problem sits deeper:

>

> DEBUG verbose: on

>

>> add a line just after common/JackServer.cpp line 66

>>  printf("DEBUG verbose2: %s\n",(JackGlobals::fVerbose)?"on":"off");

>> ...

>

> above, your line number didn't match exactly, so we seem to have

> different versions (1.9.7 here). Thus, I wasn't exactly sure where to

> add the prinf() and did the following:

>

> ...

>     JackServerGlobals::fUserCount = 1;     // One user

>     printf("DEBUG verbose2: %s\n",(JackGlobals::fVerbose)?"on":"off");

>     JackGlobals::fVerbose = verbose;

>     printf("DEBUG verbose3: %s\n",(JackGlobals::fVerbose)?"on":"off");

> }

>

> which prints:

> DEBUG verbose2: off

> DEBUG verbose3: on

>

>> A crude test for the union() hunch would be to change

>> common/JackControlAPI.h line 53:

>>  replace

>>  "union jackctl_parameter_value"

>> with

>>  "struct jackctl_parameter_value"

>> and compile with '-fpermissive' like this:

>>

>>  CXXFLAGS="-fpermissive" ./waf  configure

>>  ./waf

>>

>

> Again, mismatching line numbers. I assume you meant the line:

> union jackctl_parameter_value verbose;

>

> Changing that to struct fixes both issues I reported,

> the verbose output and exit on last client close.

>

> So we seem to be getting somewhere. Nice.

>

>

> thanks Robin,

> d

just a quick re: the line-numbers refered to git-head

  https://github.com/jackaudio/jack2/

currently 007cdc37142a
It looks like it is indeed caused by using unions to check for /true/.

  "if ([bool/int/..]union) -> always true"
But I'm at a loss what'd cause those issues and how to best fix it.

Maybe someone else can take it from here. It should be sufficient info

to file a bug report at  https://github.com/jackaudio/jack2/issues
best,

robin

_______________________________________________

Linux-audio-user mailing list

Linux-audio-user@lists.linuxaudio.org

http://lists.linuxaudio.org/listinfo/linux-audio-user