#linuxcnc-devel Logs

Jun 11 2020

12:30 PM Tom_itx is now known as Tom_L
03:21 PM jepler: good reasons to work on a new pi4 image this weekend -- the "raspberrypi-bootloader" version which supports USB booting has been released and it works on my sample of 1 brand of USB enclosure. Performance with this Samsung SSD on USB 3.0 seems pretty good. Latency is in the 30us range for 5 minutes, disk activity & glxgears loading
03:21 PM jepler: (you also need to do a raspberrypi firmare upgrade to get that functionality; not sure if that part is out of beta yet, I didn't check)
03:27 PM pcw_home: 30 us? that's great! so the GPIO driver and software stepping is a good option
03:27 PM andypugh: What do you think of the idea of adding a commanf to halcmd to set the message level?
03:28 PM andypugh: halcmd debug 6
03:28 PM jepler: andypugh: Probably a fine idea. we originally had the ability to do this via /proc but that went away a long time ago
03:28 PM jepler: pcw_home: that was only a quick test, I'm sure it increases
03:28 PM andypugh: Yes, I was just discussing that with someone.
03:29 PM andypugh: halcmd isn’t necessary the most appropriate place, but it’s probably the most convenient and usable.
03:36 PM Tom_L: the stock pi psu won't really support a ssd will it?
03:49 PM Tom_L: i see they recomend an externally powered dock for it
03:50 PM andypugh: jepler: rtapi_proc.h only gets compiled (#if ) for kernels prior to 3.10. But that includes some of the more recent OSs supported. Does rthe rest of proc.h do something useful?
03:53 PM jepler: I forget what else it does to be honest
03:53 PM jepler: I think you can inspect #s of some RTAPI objects that way or something
03:54 PM andypugh: I guess someone should look at it, but not me, tonight.
03:54 PM jepler: the only file you can write to is the debug level
03:54 PM jepler: the rest is informational
04:04 PM CaptHindsight: I think the Rpi4 is the only low cost ARM board with up to 8GB of DDR
04:05 PM CaptHindsight: the Orange pi's are 3GB max IIRC
04:05 PM jepler: I'll be picking up an 8GB model to find out whether my current image boots on it at all. If it does, it'll probably only see 4GB. grrr, who could have predicted a problem such as this
04:06 PM CaptHindsight: RockPro64 is 4GB https://www.pine64.org/rockpro64/
04:06 PM CaptHindsight: yeah waiting to see if 8GB is accessible
04:07 PM jepler: is anyone aware of reports on whether and how well preempt works on aarch64?
04:07 PM CaptHindsight: the Gentoo kernel I've been running on the Rpi4 is 64b, what is raspbian? 32 or 64?
04:08 PM jepler: raspbian has multiple kernels, but as far as I know it boots the 32-bit kernel by default on 1, 2, and 4 gb pi4S
04:08 PM jepler: * raspbian has multiple kernels, but as far as I know it boots the 32-bit kernel by default on 1, 2, and 4 gb pi4s
04:08 PM CaptHindsight: jepler: I'm working on several things at once already but...
04:08 PM jepler: https://www.get-edi.io/assets/pdfs/RealTimeLinux.pdf has some results from 4.17 on aarch64, max ltencies on the order of 1xx microseconds (see slide 7ish) https://www.get-edi.io/assets/pdfs/RealTimeLinux.pdf
04:09 PM jepler: pi3
04:09 PM jepler: yeah me too
04:09 PM CaptHindsight: jepler: If you care to test or have time https://github.com/sakaki-/gentoo-on-rpi-64bit
04:10 PM CaptHindsight: 64b Gentoo image for the Rpi4 ^^
04:10 PM jepler: I don't plan to switch to gentoo but it's good to know it's out there
04:10 PM CaptHindsight: sure, just to try premmpt-rt
04:10 PM jepler: (the userspace of all official pi images is entirely or almost entirely 32 bits)
04:10 PM CaptHindsight: might be quicker than building for raspbian
04:11 PM CaptHindsight: I'd ask Alec but he won't even look at an Rpi :)
04:13 PM jepler: I am still not super excited about them but somehow I'm muddling through it anyway
04:14 PM -!- #linuxcnc-devel mode set to +v by ChanServ
05:49 PM andypugh: Right, halcmd now has a “debug” command.
05:50 PM andypugh: (Currently it only sets message level for rtapi, but I guess it could do others too?
06:20 PM cerna: jepler: Preempt rt works on aarch64, Debian minimally.
06:34 PM jepler: how's the overall hardware support of upstream debian on the pi4 ?
06:35 PM jepler: will wifi and video work broadly at the same level of functionality?
06:39 PM cerna: I don't know about Pi4. The testing were done for/on Ultra96 https://www.96boards.org/product/ultra96/ - where it is said to work and run.
09:13 PM CaptHindsight: how long is a kernel compile on the Rpi4?
09:13 PM CaptHindsight: mine is clocked at 2GHz
09:13 PM CaptHindsight: i don't have the crosstools on x86 installed yet
09:17 PM Tom_L: an evening?
09:18 PM Tom_L: i did that and built lcnc in an evening
09:20 PM CaptHindsight: thanks
09:20 PM CaptHindsight: been running a 64b kernel on the pi
09:20 PM CaptHindsight: have to build preempt_rt
09:21 PM Tom_L: i built the preempt-rt one jt had directions for and built 2.8 on it
09:21 PM CaptHindsight: https://github.com/sakaki-/gentoo-on-rpi-64bit
09:21 PM Tom_L: jepler has an image unless you just wanna build it
09:21 PM Tom_L: about the same latency
09:22 PM Tom_L: not gentoo
09:22 PM CaptHindsight: this is 64b vs 32b
09:22 PM Tom_L: yeah
09:25 PM CaptHindsight: there is no 3GiB 'memory ceiling' anymore: if you are fortunate enough to own a 8GiB Pi4, all 8GiB of that RAM is usable.
09:29 PM CaptHindsight: seems the Gentoo devs are way ahead of Debian on ARM
09:29 PM Tom_L: wonder why raspberry sticks with debian then
09:29 PM CaptHindsight: Gentoo hard
09:30 PM Tom_L: i guess they have several options you can dl
09:30 PM Tom_L: i wasn't sure which firmware opened up the usb boot thing
09:30 PM Tom_L: for ssd
09:32 PM CaptHindsight: I wish they would have just used u-boot
09:32 PM CaptHindsight: but broadcom is why not