Install linuxcnc on preempt rt

Does anyone installed linuxcnc on preemptr rt kernel.
I download the source file and complile it but when I use the configure command it shows up RT not found.

I'm learning this also but I think you still have to download the rtai tarball unpack it and configure it in to the kernel but I'm not real clear on how.

see here> www.rtai.org and here> wiki.linuxcnc.org/cgi-bin/wiki.pl?Installing_LinuxCNC

Hi

If you install Debian 7.1 (Wheezy), you can then pull a rt version of the kernel with apt

The Unified Build Candidate 3 branch of the master will build with it.
(git checkout -b unified-build-candidate-3)

It does not require a seperate realtime package, the support is in the kernel

I have done this and tested it, but it is the worst choice of all the available realtime kernels.
The latency is by far the worst and it will throw realtime faults whilst just running a sim with no base thread, so I would not consider it for running a machine.

If you want a modern realtime kernel to run on new hardware try this
highlab.com/~seb/linuxcnc/rtai-for-3.5-prerelease/

or my 3.8.0-rtai kernel
www.linuxcnc.org/index.php/english/forum...blems?start=50#39502

My kernel is targetted at Intel Atom 2 core, but will run on other machines, the instructions on the download page should help you with the building and installing all the pre-requisite libs etc
regardless of which kernel you use

regards

Thanks for your attention, for now I used ubuntu10.04 and I compiled the kernel 3.0.95+rt_preempt patch 3.0.95.
Could you recommend me a good version if you have a stable one.

And my problem is when i use ./configure --enable-run-in-place, the system shows "RT not found,specify --with-realtime=<path>" , but I'm succed to compile the kernel, and the system is run well.

The reason is that I don't want use rtai as the realtime kernel

Could you recommend me a good version if you have a stable one.

I am guessing you mean a version of Linuxcnc that will compile with rt-preempt?

git clone git://git.linuxcnc.org/git/linuxcnc.git linuxcnc-dev

git checkout -b unified-build-candidate-3

The run ./configure --help to see the rt options

You don't need --enable-run-in-place any more, that is the default
and you may need to specify --with-rt-preempt-kernel
but the ./configure requirements keep changing so check what it requires first

The reason is that I don't want use rtai as the realtime kernel

Is there some reason why not? I think you will find rt-preempt disappointing.


regards

the git commands are a bit off (the checkout command above will give you master!); rather do this after the clone or fetch:

git checkout -b unified-build-candidate-3 origin/unified-build-candidate-3

there is no --with-rt-preempt-kernel option, rather a --with-rt-preempt open - you're not going to need it, by default the build creates support for rt-preempt and posix (aka 'sim') support

just ./configure is right most of the time

you might also want to read this document: static.mah.priv.at/public/html/common/UnifiedBuild.html , it describes all options

----

as for ease of use and install, RT-PREEMPT wins by a large margin
as for performance, the order is RTAI, Xenomai (close), RT-PREEMP (a bit distant)

however, so far nobody was able to explain to me in credible terms which actual difference a latency of 10uS versus a latency of say 30uS makes for cutting results

- Michael

mhaberler wrote:

however, so far nobody was able to explain to me in credible terms which actual difference a latency of 10uS versus a latency of say 30uS makes for cutting results

In my humble opinion: none. Even a very fast machine can only move a few microns in 20 microseconds, let alone accelerate/decelerate significantly
But with low latency comes a high possible basethread frequency, which is nice for encoder counting and stable low-jitter step/dir pulse trains towards a stepper motor or step/dir servo controller using a parallel port.

Once I have Mesa hardware I intend to set up another PC for LinuxCNC. This PC will be based on a motherboard using an Intel Z77 chipset and a Celeron G550. This is hardware I can buy locally, which I prefer. When the D525MW broke it took 6 weeks before I had it back. Unacceptable. Also, the Z77+Celeron proved to be rock stable and low latency (~12us with LinuxCNC from the LiveCD). Only disadvantage: the older 10.04 does not support that board too well. Audio not working, sensors not working, TRIM support for SSD's not available, etc.

I would prefer to use Lubuntu 12.04 or something similar. I tried the 3.4.55-rtai kernel as described in the wiki on a VirtualBox VM with rellenbergs improved TP branch, but that just freezes/hangs. Now, a VM on top of Windows7 is not realtime capable hardware, so no worries yet. Xenomai seems a more future-proof choice anyway, but no support for that in rellenbergs branch.