Ubuntu Wiki

Realtime

Basic introduction is available at:
https://help.ubuntu.com/community/UbuntuStudio/RealTimeKernel

News:
The -preempt and -rt kernels are died, aren't it?

Make-up of the team and rules officially assigned:

Persons who would want help but not yet assigned to something:
- Asmo Koskinen: Test on -rt on Maverick (AMD64 and i386) with nVidia, M-Audio Delta 66 and Echo Audio Fire 4
- Erik Rasmussen : Test on -rt
- Mike Holstein : -realtime on Lucid
- ailo : -rt on Maverick with nvidia
- Brian David:
- Laurent Bellegarde: testing, advertising, conference, demonstration to large public
- Tim Cook: test on -rt and Relationships with other communities
- Jeremy Jongepier: Test and packaging on -rt/-realtime
- Scott Lavender: testing, packaging, Ubuntu relations, and Studio relation about -lowlatency
- Janne Jokitalo: Testing, packaging, Ubuntu and Ubuntu Studio relation, learning to generally tweak kernels

Work in progress:
Nvidia on -realtime kernel at Alessio's PPA: testers?

Known issues:
Missing a decent FAQ section
ATI (fglrx): volunteers?
Firewire audio devices: again volunteers?

FAQ:
What mean when someone say "I would want -rt kernel" instead of "I would want -realtime kernel"?

From a technical point of view -rt and -realtime are the same kernel. They could diverge on PREEMPT_RT patchset version offered but both are always based on that. The main difference is that -rt should be based on Ubuntu source tree (so you can use the same features, patch, hardware enabled, security fixes and so on) and should do offer the same services that Ubuntu default and standard -generic kernel offer. For example it should be compatible with closed video drivers (nvidia and fglrx), any external DKMS drivers and make available backports package. Final goal it is to obtain a real time variant of the Ubuntu kernel (so it should be aligned with -generic too).

Instead when someone mentioned -realtime kernel he are talking about an PREEMPT_RT patched kernel based on vanilla source tree (nor Ubuntu one). So that kernels miss some Ubuntu specific code, patches or security fixes and it isn't guarantee compatibility with any external software (that is low level utility, DKMS drivers and so on) and it don't use the same Linux kernel version of the -generic one (so are misaligned). In fact it is a working upstream real time kernel version on Ubuntu no more no less.

Ancient stuff

These wiki pages covers hard real time support in Ubuntu.

RealTime Feisty
RealTime Gutsy
RealTime Hardy
RealTime Intrepid
RealTime Jaunty
RealTime Karmic
RealTime Lucid

The RT kernel is still around! If you can help by describing it's current state, please do so. In the mean time see the official rt.wiki.kernel.org and the Ubuntu Studio team for more information.