LinuxCNC install + upgrade to dev (documentation issues) plasmac related.

Hello,

Sorry I didn't know where to put this as its probably a mixture of a load of things (me being inept and or poor and or outdated and or incorrect documenation).

I have dabbled with Linux for 20 years (consider me the equivalent of a 6 month novice user, I have used bash with RPi / tinkerboaqrd etc).

So I had a working Linuxcnc RT distobution running over a Mint install I followed on here, but I thought I'd dabble with plasmac as it looks interesting (my usable cnc is UCCNC).

Given I've just replaced my PC with a fanless i7 5550u, I decided to install via a linuxcnc live install disk on USB stick, all fine, no issues, run sudo apt-get update + sudo apt-get upgrade and again no issues.

Then I thought (as it was linux 2.7r14 that I'd give the current master / development a go (2.9.0) as I'm looking to dabble with plasmac, and have done to this thread
forum.linuxcnc.org/plasma-laser/35449-an...ma-component?start=0

I followed this link on the above page
buildbot.linuxcnc.org/
and just got errors (rejected) when I ran this in terminal
giving up on that, I then went to this link on the above page:
linuxcnc.org/docs/master/html/code/building-linuxcnc.html
and after running this in terminal:]
it too just gave errors {albeit I suspect that the linuxcnc-dev is probably the issue, and maybe should be " -b master "}

again, giving up on that, I then tried this line on the above forum page:
linuxcnc.org/docs/devel/html/plasma/plas...u_have_linuxcnc_v2_7
and tried this running in terminal

git clone git clone git://github.com/linuxcnc/linuxcnc.git linuxcnc-dev

but it too spat out errors..... although I suspect that this too is because there are too many "git clone" statements in the line.

eventually.... I ran Synaptic Package Manager and upgraded linuxcnc to 2.9 from there.... which has plasmac and appears to be working.

My point is Linuxcnc never seems to make it easy for new users to try out the package if its difficult to install and the code does not run without errors.

Maybe I am nieve and expect that I should be able to install from a linuxcnc live disc and follow at least one of the methods to get it to work..... afterall that is going to be the best way to bring out new users is it not? Any maybe check that the code is correct or still works from the terminal that may have been written some time ago


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slightly seperate issue.... I was obviously testing / checking my latency, given I was running a newer fanless PC with an i7 5550u against my older N3150 fanless pc and having a look at this thread
wiki.linuxcnc.org/cgi-bin/wiki.pl?Latency-Test

I noticed that it refered to "isolcpus"

wiki.linuxcnc.org/cgi-bin/wiki.pl?The_Is..._Parameter_And_GRUB2

I thried to follow the info posted but am not sure if its still current with the latest linuxcnc / debian distro's given multiproccessor CPU's are the norm these days..... but again I'm not sure if adding "isolcpus=1" will make any difference

found this thread forum.linuxcnc.org/9-installing-linuxcnc...lspus-1-still-needed too

Note I am going to be running a Mesa 7i76E which I have so am only interested in the servo (1msec) thread / loop, but I kind of expected that the jitter would be lower than it is.

Thanks,

Rob

Robert, funny, I just copied the first 2 lines you quoted and both worked perfectly (settnig the key server and cloning from git.)
I'm sitting in front of a fresh install of Linux Mint 19.1 (tesa)

I suspect that there may be some dependencies (probably including git) that was missing.

I'm currently compiling the Linux PREEMPT_RT kernel for a mesa 7i76e and I have installed these dependencies for that purpose (you will need to do that too if you wish to continue to use Mint and a 7i76e.
I don't recommend anybody depend too much on the Wiki as its user maintained and has some obsolete info in it. Everything you need is in the docs but be sure to follow the link to the correct version as there are significant differences between versions.

Thanks for pointing out the error in the plasmac manual. I'm sure Phill will note it and push a fix over the weekend.

Right now V 2.7 is really on an end of life OS . V 2.8 has been quarantined and the Devs are working hard on completing testing and final revisions before release which will retire V 2.7. Plasmac will be in that release (minus the reverse run). So really Plasmac is a pre-release config right now. It can't run on 2.7.

I played with isolcpus and I think its acknowledged it does not help on current hardware.(again its not in the official docs - probably for a reason).

LinuxCNC does not need an i7 and would be quite happy on your old PC. The N3150 is ideal for mesa hardware. The PC I'm working on right now is a J1850 and My other PC's have been a J1900 (currently on my machine now) and a N3160. You just need to disable some power saving and some internal wifi cards result in unusable latency (replace with a USB Wifi Dongle).

Using the Synaptic package manager is the correct way to get V 2.9 (unless you want to compile the source.)

So right now I have 2 of these little J1850's one has Mint on it and the other has the Stretch 2.7 default ISO install. I was going to document the process. Maybe it might get included in some instructions somewhere.

One final note I found out while writing this. I just had a failure with Linux Mint compiling the PREEPT_RT kernel while I was writing this. So stick to the stretch ISO www.linuxcnc.org/testing-stretch-rtpreempt/

Thanks Rod,

I tried to go the "easy" route, and just used the live debian from here:
www.linuxcnc.org/testing-stretch-rtpreempt/

linuxcnc-stretch-uspace-amd64-r13.iso

onto a usb stick using rufus +dd and it booted just fine and then installed it onto the HDD (conventional disk SATA not SSD)

I'll have a play over the weekend as I really want to give linuxcnc a go for curiosity more than anything.

I didn't see the point of installing Mint this time as it shouldn't offer anything over pure debian stretch , and I found the RT patch a pia if I remember from last time.

Git appeared to be installed ... like I said I'll have another go at it.

Thanks again

Rob

Thanks all for the replies.

Been playing with mint over the weekend + (re)building kernels to (try to) improve jitter.

With Mesa hardware, you really don't need to worry too much about Jitter. I think anything under 200,000 is useable but < 100,000 is fine. I think the little PC I'm working with is about 65,000. I did not have much luck with Mint and PREEMPT_RT. Its always been easy before but this time, Its related to a known kantankerous BIOS and UFE booting. It seemed the fix might include setting different parameters in xconfig so I have not got back to it.

Yes, I'm probably over thinking / tinkering with it....

I've been following this link / thread to install mint 19.1 and patch the RT kernel + rebuild the kernel.

forum.linuxcnc.org/9-installing-linuxcnc...cnc-on-linux-mint-19
>>
gnipsel.com/linuxcnc/uspace/linuxmint19-rt.html

when I ran
I could not help but take a look at the kernel config, and one setting I found has puzzled me {given the instructions were :

Use ctrl f and search for preempt. Select Fully Preemptible Kernel(RT) Save and close

I ran across:
should this not be set at:which should improve latency?

Kernel source is here. I'm not making a call one way or another.
github.com/torvalds/linux/blob/master/kernel/Kconfig.hz

thanks got it all working at the moment (well mint 19 + linuxcnc 2.9 / dev) installed