Re: [Xenomai-help] Xenomai and mlockall

[Philippe Gerum <rpm@xenomai.org>]

On Mon, 2007-06-25 at 15:00 +0200, Johan Borkhuis wrote:
> I am trying to run my Xenomai application as non-root. I disabled 
> XENO_OPT_SECURITY_ACCESS to allow non-root users to run Xenomai 
> applications. However, this causes my application to exit with the error:
> 
> Xenomai: process memory not locked (missing mlockall?)
> 
> Is there a way to avoid this error? I am running on an embedded system 
> without swap and without disk, so there is no real need for mlock or 
> mlockall.
> 

swap is not the only source of page faults, ondemand application/library
loading is another one.

> Is there a way to "tweak" the CAP_IPC_LOCK capability of the system or 
> the task so that I can run mlockall call, or is there a way to disable 
> this check on Xenomai?

No way to disable it, since doing so would basically make your system
dysfunctional by risking page faults while not running over a regular
Linux context (i.e. Xenomai's primary domain).

IOW, you do want mlockall() to be in effect for Xenomai apps.

Hint: If you think some process is overconsuming locked memory, you may
want to have a look at /proc/<pid>/maps for the process in question, and
check the size of the various segments listed there, and especially the
stack related one.

> 
> Kind regards,
>     Johan Borkhuis
> 
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-- 
Philippe.