Christos Posted October 2, 2016 Share Posted October 2, 2016 Hi, Seen some posts where mentioning that depending of the version of kernel there is either FEX or DTS usage, old ones called Legacy, using FEX to define GPIOs and Peripherals pins. Wit Mainline Kernel, is using DTS. Yet in the recent kernel (dev) armbian builds, eg armbian 5.21, kernel 4.7.6 (on H3, NEO), seen the /boot containing all the FEX stuff script.bin etc. Is FEX still used in the mainline kernel builds? C:\Christos>ssh christos@192.168.1.131 christos@192.168.1.131's password: setsockopt IP_TOS 16: Invalid argument: _ _ ____ _ _ _ | \ | | __ _ _ __ ___ | _ \(_) | \ | | ___ ___ | \| |/ _` | '_ \ / _ \| |_) | | | \| |/ _ \/ _ \ | |\ | (_| | | | | (_) | __/| | | |\ | __/ (_) | |_| \_|\__,_|_| |_|\___/|_| |_| |_| \_|\___|\___/ Welcome to ARMBIAN Debian GNU/Linux 8 (jessie) 4.7.6-sun8i System load: 0.00 Up time: 37 min Memory usage: 9 % of 495Mb IP: 192.168.1.131 CPU temp: 34Β°C Usage of /: 8% of 15G Last login: Sun Oct 2 13:27:36 2016 from 192.168.1.6 christos@nanopineo:~$ su root Password: root@nanopineo:/home/christos# cd /boot root@nanopineo:/boot# ls -l total 15788 drwxr-xr-x 2 root root 4096 Oct 2 08:32 bin -rw-r--r-- 1 root root 6944 Oct 2 08:33 boot.bmp -rw-r--r-- 1 root root 2846 Oct 2 08:27 boot.cmd -rw-r--r-- 1 root root 2918 Oct 2 08:35 boot.scr -rw-r--r-- 1 root root 140522 Oct 2 08:22 config-4.7.6-sun8i lrwxrwxrwx 1 root root 15 Oct 2 08:32 dtb -> dtb-4.7.6-sun8i drwxr-xr-x 2 root root 4096 Oct 2 08:32 dtb-4.7.6-sun8i -rw-r--r-- 1 root root 3995879 Oct 2 08:33 initrd.img-4.7.6-sun8i lrwxrwxrwx 1 root root 17 Oct 2 08:32 script.bin -> bin/nanopineo.bin -rw-r--r-- 1 root root 2203811 Oct 2 08:22 System.map-4.7.6-sun8i -rw-r--r-- 1 root root 3995943 Oct 2 08:33 uInitrd -rwxr-xr-x 1 root root 5794016 Oct 2 08:22 vmlinuz-4.7.6-sun8i lrwxrwxrwx 1 root root 19 Oct 2 08:28 zImage -> vmlinuz-4.7.6-sun8i root@nanopineo:/boot# So if I change only the script.bin with bin2fex/fex2bin do these changes be effective in armbian latest kernel builds 4.x? Christos Link to comment Share on other sites More sharing options...
tkaiser Posted October 2, 2016 Share Posted October 2, 2016 Is FEX still used in the mainline kernel builds? No, you can do what you want with fex files, any kernel with 4.x will ignore everything here. Vanilla == device tree, Allwinner legacy == fex files. To make things worse, it seems Allwinner's most recent BSP kernel for newer Allwinner SoCs (A64 and eg. the upcoming R40) could use both at the same time). But as a rule of thumb: Only if you're dealing with kernel 3.4 on an Allwinner device fex settings are used. Otherwise it's DT. Link to comment Share on other sites More sharing options...
Christos Posted October 2, 2016 Author Share Posted October 2, 2016 Ok, Can you please give us dts noobs, a couple of (easy to digest but informative) links with info on the DTS stuf used in armbian? It looks its the way to go from now on.. Christos Link to comment Share on other sites More sharing options...
tkaiser Posted October 2, 2016 Share Posted October 2, 2016 I'm a noobie here too and believe the best you could do is to look into Thomas Petazzoni's 'Device tree for Dummies' as a start. The only important and Armbian specific information is IMO this: When you play around with the dtc tool and make changes then don't overwright the original .dtb files. Create a new version and then simply use the instructions here to adjust $fdtfile as outlined here: http://docs.armbian.com/boards/bananapiplus/ This way you do not loose the original .dtb file and can recover from errors that prevent booting (on another Linux host of course). Link to comment Share on other sites More sharing options...
Christos Posted October 2, 2016 Author Share Posted October 2, 2016 Ok thanks, Just to confirm though, I've seen a few posts in armbian, eg -> http://forum.armbian.com/index.php/topic/993-ds18b20-temperature-sensor-in-lamobo-r1/ where they modify BOTH the fex and the dts in order to achieve their goal. I guess that is redundant? only the dts needs change right? Christos P.S. BTW, these are some real case examples found in the forum here regarding dtc, so I sum them up just in case they are useful to someone that wants to have a look, together with Thomas's hints made me get an idea of what the dtc is http://forum.armbian.com/index.php/topic/382-armbian-on-pcduino3/?p=2444 http://forum.armbian.com/index.php/topic/993-ds18b20-temperature-sensor-in-lamobo-r1/?p=16089 http://forum.armbian.com/index.php/topic/385-banana-pi-usb-otg/?p=7773 http://forum.armbian.com/index.php/topic/82-spi-on-olinuxino-a20-micro-with-device-tree-kernel/?p=827 P.S. 2 -> http://free-electrons.com/pub/conferences/2012/elce/arm-soc-checklist/arm-soc-checklist.pdf -> https://events.linuxfoundation.org/sites/events/files/slides/petazzoni-device-tree-dummies.pdf -> The purpose of the Device Tree is to move a significant part of the hardware description into a data structure that is no longer part of the kernel binary itself. -> This data structure, the Device Tree Source is compiled into a binary Device Tree Blob -> The Device Tree Blob is loaded into memory by the bootloader, and passed to the kernel. -> It replaces all the board-*.c files, and removes all the manual registration of platform_device. Also, no longer needed to have Kconfig options for each board. -> Usage of the Device Tree is mandatory for all new ARM SoCs. No way around it. Link to comment Share on other sites More sharing options...
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