On 28.01.22 23:25, gene heskett wrote:
On Friday, January 28, 2022 2:21:50 PM EST gene heskett wrote:
On Friday, January 28, 2022 1:32:52 PM EST gene heskett wrote:
On Friday, January 28, 2022 10:18:38 AM EST Steffen Möller wrote:
...
Processing linuxcnc-uspace_2.9.0~pre0_arm64.deb...
...
Install them on a pi, and run latency-test please.
Are you running on 64bit? Then the packages should work.
Not on the pi's, always armhf. arm64 is too slow. This runs fine on a
pi3 even, but the rpi3 is dragging its tongue on the floor, I had to
move some of the lower response stuff to a slower thread to give the
quick stuff enough time to work on the rpi3b and can't do much else
at
the same time, but it did get the job done before the rpi4 came out.
Machine control, in close enough to real time demand low irq latency.
For normal pc's AMD processors don't do that even running rtai
kernels, but intels from about 586 had managed it well enough to work
but i5's are amazing. Even atoms ran it well enough to get the job
done here for about a decade but they've all died for various reasons
associated with the bblb syndrome now. I've got 2 I need to recycle
but haven't made the trip to the recycle trailer yet. I bought a
stack
of off-lease Dells to replace the atoms with, works very well with my
only complaint about Dells being the 2 sata ports max. Running from
SSD's you would swear they are brand new state of the art machines.
You may be able to build it on arm64's but linuxcnc checks to see if
certain resources are available that are only available from a
realtime, fully preemptable kernel, making a graceful exit if they
aren't found.
Tell you what, I just found a debian armhf net-install image for armhf
in 11.2, and since I can't get it built on a raspios bullseye, I'll
rewrite that card and start from scratch with a genuine debian 11.2
install, just to see if I can make it run, with this kernel, on your
bullseye.
When I have something to report, I will.
And I can confirm that the armhf net-install of 11.2, will not boot on a
pi. That is assuming dd can write a valid .iso to an sd card just as it
writes the raspios .img files. So a good .iso should, and has worked just
fine several times, but two writes of the .iso have refused to look at
the card after the first green flash of the disk activity led.
Then I found my card reader was on strike, so I drove out to the other
side of town to walmart and bought two more readers, along with a
keyboard cuz the space bar on this one is getting funkity, and 2 more 64G
micro-cards.
I rewrote the debian net-install image, then inspected it with fdisk, to
discover the debian iso I had just written to it for /dev/sdk, partition
1 while a dos (vfat to linux) image is also an EFI image, the first one
that pi has ever seen.
So Steffen, if you want me to try your distro, respin that .iso w/o the
EFI. The pi doesn't take more than a 10 millisecond glance at this .iso.
Thank you tons for your efforts.
I gave all my RPis away, so I must admit, so I cannot easily follow up.
It will take a bit for an RPi4 to arrive. And a comparison of latencies
on 32 and 64 bits will also be interesting.
All bullseye variants on whatever platform should just somehow get
LinuxCNC compiled, so I am indeed curious to learn what is going on.
Best,
Steffen
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