#linuxcnc-devel Logs

Feb 19 2018

#linuxcnc-devel Calendar

04:32 PM jepler: reportedly the next SBC from odroid will have a RK3399 CPU. It has a PCIe port internally, but it will just be connected to the SATA controller. It also has a gigabit ethernet MAC directly in the CPU, so maybe Mesa ethernet cards would work.
04:34 PM jepler: 4GB RAM, 64-bit Cortex-A72, eMMC storage, $110 price point
04:35 PM seb_kuzminsky: link?
04:35 PM jepler: http://www.hardkernel.com/?b193
04:35 PM jepler: We’ve ported and tested Kernel 4.14 as well as 4.4. The latest Kernel 4.14 works fine except for some VPU/GPU driver glitches.
04:36 PM jepler: Due to this, we may keep using Kernel 4.4 until Rockchip releases a stable 4.14 BSP. Kernel 4.4 LTS will be maintained until Feb, 2022 by Greg Kroah-Hartman.
04:36 PM jepler: so you still have to play stupid nonmainline kernel dance, but 4.4 at least has preempt-rt patchset
04:36 PM seb_kuzminsky: oh yeah, the N1
04:36 PM seb_kuzminsky: lol they're inviting their community to a debug party
04:39 PM jepler: opensource.rock-chips.com/wiki_Upstream_Kernel claims "mainline kernel supports: ... RK3399"
04:40 PM seb_kuzminsky: how does big.LITTLE work?
04:41 PM jepler: XU4 is big.LITTLE too
04:41 PM jepler: the way it works is, if you just ignore the LITTLE cores you get better performance
04:42 PM jepler: at least in some compile tests I did back in the day, trying to do 8 in parallel to use the big and LITTLE cores didn't see a speed benefit
04:42 PM jepler: LinuxCNC wouldn't know to avoid a LITTLE core / bind to a big core for its RT thread
04:42 PM seb_kuzminsky: memory bus contention maybe
04:43 PM jepler: or even total RAM
04:43 PM jepler: 4GB isn't much to run 8xgcc even if it's not compiling those terrible files in rs274/
04:47 PM jepler: 925791 / 1000001 values found, searching strings of length 11, 151.5 billion searches
04:50 PM pcw_home: supposedly the Odroid C2 runs hm2_eth OK
04:52 PM jepler: I see it also has a gigabit mac on the CPU
04:52 PM jepler: I had overlooked that fact
04:56 PM pcw_home: I think the potato has the same basic hardware as the C2
07:39 PM seb_kuzminsky: pcw_home: the libre potato looks interesting, for the price
07:39 PM seb_kuzminsky: https://libre.computer/products/boards/aml-s905x-cc/
07:40 PM seb_kuzminsky: that balance of cpus vs ram is a little off for a linuxcnc build machine
07:41 PM seb_kuzminsky: all the libre computers are less powerful than the odroid n1, but also they're less than half the price