**** BEGIN LOGGING AT Tue Jan 09 03:00:01 2018 Jan 09 08:43:58 q Jan 09 11:21:13 Do you know a way to have the X15 boot automatically on power? Jan 09 11:34:01 Hi Jan 09 11:34:31 does beaglebone support multiple SSID / wifi channels? Jan 09 12:08:28 fanman: that was just discussed recently, it's not built into the hardware but you should be able to make a pretty simple circuit (drag a 555 timer out of the junk drawer) to make a power-on pulse for it. Jan 09 12:10:08 https://groups.google.com/forum/embed/?&parenturl=http%3A%2F%2Fbeagleboard.org%2Fx15&showsearch=true&showpopout=true&showtabs=true&place=forum/beagleboard-x15#!searchin/beagleboard-x15/auto$20power/beagleboard-x15/fck_GaOiV_o/tQZoS9spFgAJ Jan 09 17:07:55 fanman/myself: actually you can forcibly enable it, but the side-effect is that you won't be able to shut down under software control, and if the board powers on without any bootloader present it won't automatically power down after a few seconds like it normally would.... staying on in that state for extended time may damage the board Jan 09 17:08:39 if those contraints are okay for you, if you're sure it will always load u-boot after powering on, then you just need to connect some jumper iirc Jan 09 21:52:18 How tolerant is Linux w.r.t. power failures? (Assuming all user space files are closed and ext3/4 is used) Jan 09 21:54:50 journaled filesystem, so anything will clean itself up on boot Jan 09 21:55:53 is that also true for the kernel? no files used by kernlen right? Jan 09 21:57:03 *kernel Jan 09 21:57:07 yes. Also you could have your rootfs mounted ro Jan 09 21:57:30 and write logs or whatever to tmps or some small separate partition Jan 09 21:57:54 ok that's a good point, thanks for the advice, forgot about the mount RO trick for root Jan 09 21:58:57 note that in case of am335x the hardware doesn't necessarily like constant and repeated powerloss Jan 09 22:01:32 tbr: ok Jan 09 22:13:24 zarzar1: linux isn't the problem, eMMC is Jan 09 22:14:08 zmatt: you mean with the beagle and power failures? Jan 09 22:15:42 power failures during eMMC writes can result in corrupted or even unstable data, even in areas other than the one(s) being written Jan 09 22:16:46 for our production beaglebones we reconfigure eMMC into SLC mode and enable "reliable writes" to hopefully minimize the risks Jan 09 22:16:46 ok Jan 09 22:17:03 (reconfiguring eMMC into SLC sacrifices 50% of its capacity though) Jan 09 22:17:18 hmm, looking up slc Jan 09 22:17:27 (also, this reconfiguration is irreversible) Jan 09 23:59:22 Whoah, I had no idea that was possible, that's wild. Jan 10 00:01:59 I've heard of enterprise SSDs with capacitors to finish out a write when power fails, now I need to dig up the emmc datasheet and see if it supports that too Jan 10 00:29:10 sure, all you need to do is keep the beaglebone powered using big capacitors and finish your writes before they run out :P Jan 10 00:29:21 and tell the eMMC to prepare for power-down Jan 10 00:29:41 or, at least just cancel your writes and tell the eMMC to prepare for power-down Jan 10 00:29:56 (ext4 journal should take care of the rest) Jan 10 00:30:47 don't expect too much from the eMMC on the BBB, it's the cheapest Kingston eMMC you can buy **** ENDING LOGGING AT Wed Jan 10 03:00:02 2018