[linux-audio-user] kernel2.6: realtime lsm and allcaps=1

Jack O'Quin joq at io.com
Tue Jul 6 23:20:35 EDT 2004

Antonio <debian at fastwebnet.it> writes:

> I've installed a Debian Sarge with kernel 2.6.6, jack 0.94 and
> realtime-lsm 0.1.1 to have the realtime capabilities for the normal
> user.
> The default is to set gid=<audio_group_gid>, but I'm not able to start
> jack from a user in the audio:
> $ jackstart
> jackstart: cannot get realtime capabilities, current capabilities are:
>             =ep cap_setpcap-ep
>      probably running under a kernel with capabilities disabled,
>      a suitable kernel would have printed something like "=eip"

Just run `jackd', instead.

> Neither the any=1 parm does the job. If I reload the module with the
> allcaps=1, then I can start jack from a normal user.

This is because `jackstart' requires capabilities, only available with

> Am I missing something? Is not insecure to run jack via allcaps=1?

Only a little.  But, you don't need it if you run `jackd' instead.

> Anyway, with the 2.6 series I've got a lot of xruns. I've read that
> maybe the problem is, instead,  with the new version of libc. Someone
> knows more on it, and is there some workaround?

Yes, set LD_ASSUME_KERNEL=2.4.19 in your environment for the JACK
server and every client process.  Easiest way is to set it globally.

I'm working on an update to the JACK FAQ to cover this.  The current
draft version is here...


Comments, clarifications and corrections are welcome.  Soon I will
post it to the JACK website.

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