[LAD] JACK and vanilla 3.19.2 startup issue

Adrian Knoth adi at drcomp.erfurt.thur.de
Sat Apr 4 19:13:18 UTC 2015

On 04/04/15 19:08, Harry van Haaren wrote:

> Any suggestions as to what's going on? Thanks, -Harry

Not enough information. I recommend starting jackd with strace, so you
get an idea what's actually failing. Also read the code that generates
said message:


The key thing here is system_user_can_rtprio():


This code tries to call sched_setscheduler() with SCHED_FIFO. My bet is
that your "almost vanilla kernel" fails to fulfil this request, but
strace will tell you for sure.

The question is why said call should fail. The only thing that comes to
my mind are CGROUPS. Maybe your old kernel comes without, the new kernel
supports them and the configuration is set in a way that disables
SCHED_FIFO by default.

You could of course always diff the two kernel configs and roll your
own (or just recompile vanilla 3.19.x with your 3.18 config). Maybe
there are new config options that interfere or change the defaults.


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