Will Dapper support RLIMIT_RTPRIO?

[Dana Olson]

On 2/5/06, Lee Revell <rlrevell at joe-job.com> wrote:
> 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).


I checked the Official PAM source at SourceForge, and there is a
discrepency with that patch - the resource name is officially "rtprio"
whereas most of the patches I've seen floating around have "rt_prio"
so I uploaded a new patch, which includes the DEFINES patch that I got
from Wolfgang.
http://librarian.launchpad.net/1557675/pam-0.79-rlimits.patch

It works great here, and is closest to the official PAM. I did this
tonight, so it is current as of libpam-modules 0.79 3ubuntu8.

What do we have to do to get this put into Dapper officially before release?

I could work on glibc and bash patching next, but this patch for
libpam-modules is sufficient to get us realtime access in Dapper,
OOTB.

Dana


> 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
>
>
>
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