tom.k.cook
Posts: 46
Joined: Fri Jun 22, 2012 8:51 am

RT-Preempt Kernel

Fri Jun 22, 2012 8:55 am

I hope this is the right place to post this.

Has anyone made any progress building a kernel with Ingo Molnar's RT-Preempt patch applied? I've seen others have had success with Preempt kernels, but can't find anything on the RT variant.

I'm looking to have a go at it, but one of the difficulties is that the RPi kernel is based on the (development branch) 3.1.19, while RT-Preempt is only published for stable 3.0 and 3.2 series kernels.

Does anyone have any advice to offer before I plunge in?

Cheers,
Tom

dom
Raspberry Pi Engineer & Forum Moderator
Raspberry Pi Engineer & Forum Moderator
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Joined: Wed Aug 17, 2011 7:41 pm
Location: Cambridge

Re: RT-Preempt Kernel

Fri Jun 22, 2012 9:03 am

Start with bootc's 3.2 kernel.
http://www.bootc.net/archives/2012/06/1 ... 20-kernel/

(the R-Pi official images are likely to switch to this in the future).

tom.k.cook
Posts: 46
Joined: Fri Jun 22, 2012 8:51 am

Re: RT-Preempt Kernel

Fri Jun 22, 2012 9:05 am

Freeeow, that was quick. And exactly what I was looking for. Thanks!

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AndrewS
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Re: RT-Preempt Kernel

Fri Jun 22, 2012 9:57 am

tom.k.cook wrote:I'm looking to have a go at it, but one of the difficulties is that the RPi kernel is based on the (development branch) 3.1.19, while RT-Preempt is only published for stable 3.0 and 3.2 series kernels.
(Sorry, bit OT...)
I thought with the switch to the 3.x.y numbering scheme (which AIUI is simply a continuation of the 2.6.x.y scheme) that the odd=development even=stable was no longer being used? (i.e. everything apart from the "rc" releases is stable)

tom.k.cook
Posts: 46
Joined: Fri Jun 22, 2012 8:51 am

Re: RT-Preempt Kernel

Fri Jun 22, 2012 10:17 am

AndrewS wrote: (Sorry, bit OT...)
I thought with the switch to the 3.x.y numbering scheme (which AIUI is simply a continuation of the 2.6.x.y scheme) that the odd=development even=stable was no longer being used? (i.e. everything apart from the "rc" releases is stable)
Quite right, it seems. Nonetheless, there doesn't seem to be a RT-Preempt patch for 3.1-series kernels (or 3.3 for that matter) - only 3.0, 3.2 and 3.4.

Brokentoaster
Posts: 4
Joined: Wed Jun 27, 2012 9:24 pm

Re: RT-Preempt Kernel

Thu Jun 28, 2012 7:18 pm

Is anyine working on porting the 3.2 RT-PREEMPT patchset to the Raspi?

mung
Posts: 506
Joined: Fri Nov 18, 2011 10:49 am

Re: RT-Preempt Kernel

Fri Jan 04, 2013 2:06 am

I had a previous version of the rpi 3.2.27 kernel patched and booting with RT_PREEMPT, I recently downloaded the zippped archive of the git repo and patched t without error again.

Unfortunatly I can no longer boot the kernel using the same .config as before as it seems to crash.

I have not looked into it much yet maybe will get time to this weekend.

attached is a photo of the boot screen, doubt if it will help much, I will try compile with further debug options later.
Attachments
rtpreempt_crash1.png
rtpreempt_crash1.png (25.55 KiB) Viewed 2728 times

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Licaon_Kter
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Location: Between the keyboard and the chair.

Re: RT-Preempt Kernel

Sun Jan 06, 2013 10:06 pm

mung wrote:I had a previous version of the rpi 3.2.27 kernel patched and booting with RT_PREEMPT, I recently downloaded the zippped archive of the git repo and patched t without error again.
may keep an eye on this thread: http://www.raspberrypi.org/phpBB3/viewt ... =71&t=9634
I'll try another throw at RT/BFS pretty soon
BFQ+BFS or RT on a RPi? 4'real: https://github.com/licaon-kter/ (source and compiled!)

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