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| <<BR>><<BR>> For more a more in-depth look at kernels, please see: [[https://wiki.ubuntu.com/Kernel/Dev]] <<BR>><<BR>> |
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| The -preempt and -rt kernels are died, aren't it? | The -preempt and -rt kernels are no longer being developed due to lack of support. Focus has instead turned to the -lowlatancy and -realtime kernels, particularly for the the release of Ubuntu 11.04 Natty Narwhal. The long-term goal is to have -lowlatency in the official Ubuntu repositories, while maintaining -realtime in a dedicated PPA.<<BR>><<BR>> If you wish to see work continued on -preempt or -rt, you are encouraged to volunteer. To do so, join the Ubuntu Studio Developers e-mail list (see [[http://ubuntustudio.org/|Ubuntu Studio]]). |
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| - Brian David: <<BR>> | - Brian David: Testing fglrx in all kernel variants, testing -realtime and -rt kernels, if available<<BR>> |
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| What mean when someone say "I would want -rt kernel" instead of "I would want -realtime kernel"? | Q: What is the difference between an -rt kernel and a -realtime kernel? |
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| 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. |
A: From a technical point of view, -rt and -realtime are the same kernel. They are both based on the PREEMPT_RT patchset, although the version may be different. The main difference is that the -rt kernel should be based on the Ubuntu source tree (and therefore can use the same features, patches, enabled hardware, security fixes and so on) and should offer the same services that the Ubuntu default -generic kernel offers. For example, it should be compatible with closed video drivers (nvidia and fglrx), any external DKMS drivers, and have available backport packages. The goal of an -rt kernel is to obtain a real time variant of the Ubuntu kernel that is aligned with the -generic kernel. <<BR>><<BR>> On the other hand, the -realtime kernel is a PREEMPT_RT patched kernel based on the vanilla source tree (not the Ubuntu source). This kernel will be missing Ubuntu specific code, patches or security fixes and it isn't guaranteed to be compatible with any external software (low level utilities, DKMS drivers and so on). It does not use the same Linux kernel version as the -generic kernel, and so these two kernels are not aligned. It is a working, upstream real-time kernel that is being used on Ubuntu. No more no less. |
Realtime
Basic introduction is available at:
https://help.ubuntu.com/community/UbuntuStudio/RealTimeKernel
For more a more in-depth look at kernels, please see: https://wiki.ubuntu.com/Kernel/Dev
News:
The -preempt and -rt kernels are no longer being developed due to lack of support. Focus has instead turned to the -lowlatancy and -realtime kernels, particularly for the the release of Ubuntu 11.04 Natty Narwhal. The long-term goal is to have -lowlatency in the official Ubuntu repositories, while maintaining -realtime in a dedicated PPA.
If you wish to see work continued on -preempt or -rt, you are encouraged to volunteer. To do so, join the Ubuntu Studio Developers e-mail list (see Ubuntu Studio).
Make-up of the team and rules officially assigned:
Leader |
|
|
i386 amd64 |
vacant |
Code & Packaging |
Natty |
-lowlatency |
i386 amd64 |
Luke Yelavich |
Upstream relationship |
Natty |
-realtime |
i386 amd64 |
Alessio Igor Bogani |
Bug triage |
|
|
|
vacant |
Kernel and DKMS external driver upload |
Natty |
-lowlatency |
i386 amd64 |
Luke Yelavich |
Test |
Lucid |
fglrx on -realtime |
i386 |
Brian David |
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: Testing fglrx in all kernel variants, testing -realtime and -rt kernels, if available
- 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:
Q: What is the difference between an -rt kernel and a -realtime kernel?
A: From a technical point of view, -rt and -realtime are the same kernel. They are both based on the PREEMPT_RT patchset, although the version may be different. The main difference is that the -rt kernel should be based on the Ubuntu source tree (and therefore can use the same features, patches, enabled hardware, security fixes and so on) and should offer the same services that the Ubuntu default -generic kernel offers. For example, it should be compatible with closed video drivers (nvidia and fglrx), any external DKMS drivers, and have available backport packages. The goal of an -rt kernel is to obtain a real time variant of the Ubuntu kernel that is aligned with the -generic kernel.
On the other hand, the -realtime kernel is a PREEMPT_RT patched kernel based on the vanilla source tree (not the Ubuntu source). This kernel will be missing Ubuntu specific code, patches or security fixes and it isn't guaranteed to be compatible with any external software (low level utilities, DKMS drivers and so on). It does not use the same Linux kernel version as the -generic kernel, and so these two kernels are not aligned. It is a working, upstream real-time kernel that is being used 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.
RealTime (last edited 2011-02-23 10:51:46 by cache1)