Will Dapper support RLIMIT_RTPRIO?

[Lee Revell]

On Fri, 2006-02-03 at 02:04 -0800, Matt Zimmerman wrote:
> On Thu, Feb 02, 2006 at 04:48:20PM -0500, Lee Revell wrote:
> > The new RLIMIT_RTPRIO was introduced in kernel 2.6.12 to selectively
> > allow non-root processes to run tasks with realtime priority.  This is
> > essential if we ever want reliable multimedia performance without
> > forcing users to run as root.
> > 
> > Supporting this new rlimit requires some changes to glibc, bash, and
> > PAM.  It was added to glibc 6 months ago:
> > 
> > http://sourceware.org/ml/libc-hacker/2005-06/msg00005.html
> > 
> > Presumably Dapper will ship with a post 2.6.12 kernel - so will Dapper
> > ship with full userspace support for this new rlimit?
> > 
> > I checked the current glibc sources and these new RLIMITs are not yet
> > supported...
> 
> Dapper feature freeze begins 2006-02-23.  If you submit the appropriate
> non-invasive patches in time for them to be merged before that date, I see
> no reason not to include them.  However, as yet, there is no motive to push
> ahead of our upstreams on this point except for your request.
> 

Here is some information including links to my original Debian bug
report, #17348, which now has a PAM patch attached that should be
sufficient to get this working in Dapper.

Lee

> On Fri, 2006-02-03 at 17:08 -0500, Lee Revell wrote:
> > On Fri, 2006-02-03 at 17:01 -0500, Dana Olson wrote:
> > > This is certainly beyond the scope of my current knowledge. I
would
> > > like to help, but I don't think I can research and learn that all
> > > before the deadline. Do you know anyone who would help out with
this?
> > >
> >
> > In theory it should be easy - bash, PAM, and glibc all support the
new
> > rlimits in their development versions, I just have to backport the
> > patches to whatever is in Dapper right now... we'll see how hard
that
> > is.  The bash maintainers have been helpful, and hopefully that
glibc
> > patch still applies...
>
> Can someone point me to the patch against PAM 0.79, I remember it was
> posted here a while back...
>
> Lee

Lee,

I saw your ancient bugreport #17348 
(https://launchpad.net/distros/ubuntu/+source/pam/+bug/17348), Will
Dyson 
added a patch recently 
(http://librarian.launchpad.net/1510182/pam-rtlimits.patch) to it which
seems 
to be good (it works for me on Kubuntu Dapper).

As mentioned by Dana, I've added a howto for rtprio-aware PAM on Dapper
to his 
wiki at
http://ubuntustudio.com/wiki/index.php/Rlimits-Aware_PAM_with_Dapper

Concerning glibc and bash, there are patches at 
http://sources.redhat.com/ml/libc-hacker/2005-06/msg00005.html and for
bash 
in Fedora CVS at 
http://cvs.fedora.redhat.com/viewcvs/rpms/bash/devel/bash-ulimit.patch

I've patched glibc-2.3.5 and bash on a linuxfromscratch-based system 
successfully, but I can't tell whether these work on Dapper, since bash 
failed to rebuild for me (unpatched). I'm new to Debian packaging, so
maybe I 
screwed something up.

I'm very interested to see this move into Dapper before freeze, so if I
can 
help, please ask me to.

Wolfgang