Re: [LAU] Fedora 12 & CCRMA

From: Fernando Lopez-Lezcano <nando@email-addr-hidden>
Date: Mon May 17 2010 - 08:49:06 EEST

On Sun, 2010-05-16 at 22:36 -0700, Niels Mayer wrote:
> On Sun, May 16, 2010 at 7:12 PM, Fernando Lopez-Lezcano
> <nando@email-addr-hidden> wrote:
> > > Speaking of pulseaudio,
> http://old.nabble.com/Re:-Fwd:-jack2-p28288652.html is
> > > a potential bad interaction between pulseaudio and jack
> (through
> > > /etc/security/limits.conf, potential priority escalation
> issue).
> ...
> Not that many "tweaks". The ability for all users to run jack
> with
> realtime scheduling is "added" when you install the Planet
> CCRMA jack
> package. That thread talks about some security problems that
> could arise
> with the use of realtime scheduling, that is definitely not
> the source
> of your problems.
>
>
> I'm not so sure about that... It might be a good idea to make sure
> it's not the same problem described
> here: http://old.nabble.com/Re:-Fwd:-jack2-p28296197.html
>
>
> I experienced the similar lockup problems with jackd/qjackctl prior to
> my change
> ( http://old.nabble.com/help-w--qjackctl-locks-up-X-GUI-(perhaps-caused-by-dbus-or-kernel-2.6.32.11-99.fc12.x86_64)-to28221239.html#a28224046 ). Note that these lockups DO NOT require a reboot. What's happened is that the GUI/Xserver ends up getting locked up (via qjackctl) so if you SSH in to your box and "killall qjackctl" you'll unlock ( Make sure to also do "killall jackd" afterwards.). Unfortunatelythe X server is so locked-up that you can't Alt-F2 and login via console and kill it that way.

Looks like a different issue. The computer is not locked AFAICT. It was
only rebooted because jackd is unkillable (maybe it could have beeen
killed by kill -9 but that was not tried - even then the
hardware/software might be left in a bad state needing a reboot).

Only Ardour is hung, most probably because jack itself is hung, most
probably due to a driver vs. hardware problem.

> HOWEVER -- in testing out a new $5.00 soundcard, I also experienced
> transient lock-ups again with jackd/qjackctl. The one thing that I
> could point to consistently as causing problems: having the wrong
> settings in 'alsamixer', i.e. when one of these is set to "on" you can
> neither play directly through ALSA, and jackd will hang:
> ( http://old.nabble.com/Re:-QXGEdit-(was-Re:-Suzuki-QC1-Qchord-Digital-Songcard-Guitar-)-p28541528.html )
> ** in alsamixer (F3-playback):
> Item: "Multi Track Rate Locking" set to [Off]
> Item: "Multi Track Rate Reset" set to [Off]
>
>
> Likewise, if the card is locked to the wrong sampling rate , jack may
> not be able to reset it if the above settings are wrong.... To make
> things worse, it seems like some of these settings are "sticky" and
> may require loading/unloading the driver module or rebooting for the
> change to take effect.
>
>
> Similar badness may be going on w/ your soundcard, which has been a
> source of longstanding problems in jack and alsa ... problems that
> often can be remedied via alsamixer
> magic: http://www.google.com/search?hl=en&q=SiS+SI7012
> +jackd&aq=f&aqi=&aql=&oq=&gs_rfai=

Those reasons seem more likely.

We should wait till we hear what comes out of basic tests of command
line invocations of jackd. So far the only test is running ardour which
does not give any feedback on what might be happening.

-- Fernando

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Received on Mon May 17 12:15:02 2010

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