January 2022 - Talk - lists.gtalug.org

war story: power failure makes CentOS system unbootable
by D. Hugh Redelmeier 29 Sep '22

29 Sep '22

tl;dr / spoiler: change fstab so that /boot/efi is not automatically mounted. See the recommendation at the end of this message. My gateway computer is a little PC running CentOS. It does not come back after a power failure. The reason (as best I can tell) is interesting and I think that I have a fix. My system is UEFI. It boots from a UEFI system partition, known as /boot/efi to Linux. If this gets corrupted, it won't boot. It is a VFAT partition. On my gateway (a Zotac Zbox RI321, a cute little box with two ethernet ports), the UEFI firmware apparently won't boot if the dirty bit is set in the system partition. CentOS normally runs with /boot/efi mounted. So when the system isn't shut down cleanly, the dirty bit will be on. Consequence: the system is not going to boot after a power failure. Odd observation 1: if I put a live Fedora 25 USB stick in the system and try to boot in this otherwise-unbootable state, CentOS boots from the main disk. So this really looks like a firmware bug/quirk. Odd observation 2: fsck doesn't seem to automatically fix the system partition. Once CentOS 7 booted, I dismounted /boot/efi and did an fsck on it. $ sudo fsck /dev/sda1 fsck from util-linux 2.23.2 fsck.fat 3.0.20 (12 Jun 2013) 0x25: Dirty bit is set. Fs was not properly unmounted and some data may be corrupt. 1) Remove dirty bit 2) No action ? 1 Leaving filesystem unchanged. /dev/sda1: 16 files, 2420/51145 clusters Googling got me to <https://www.centos.org/forums/viewtopic.php?t=50917> In particular, this advice seemed quite good: ==== recommendation ==== Two other changes I recommend for UEFI systems, to each OS's /etc/fstab. - For the /boot/efi mountpoint, add the mount options x-systemd.automount,noauto - Change fs_passno (last column) to a 1 or 2; the canonical fstab instructions suggest 2, but systemd treats 1 and 2 as the same. The first change means the EFI System partition will not be automatically read-write mounted at boot time; it's a bad idea this is the default because it puts the ESP at risk especially if ther are crashes, FAT has no journal and will therefore always be marked dirty in such a case; no other UEFI OS mounts the ESP by default. Second, if anything tries to access /boot/efi (read or write), systemd will automatically mount it, and because of the fs_passno 1 or 2, it will fsck it first and that fixes and clears the dirty bit in case it's set. Right now without these changes, it's just a matter of having the right number and bad timing of crashes to render the EFI System partition corrupt.

3 9

[GTALUG-Announce] February Meeting Reminder
by Alan Heighway 03 Feb '22

03 Feb '22

*When: *Feb 8, 2022 7:30PM *Speaker:* D. Hugh Redelmeier *Topic:* Gitlab fundamentals followed by Q&A and Discussion *Date/time:* 2022-01-11 T19:30:00 *Location:* Virtual - Big Blue Button (link above) --- GTALUG Announce mailing list announce(a)gtalug.org https://gtalug.org/mailman/listinfo/announce

2 1

decent cheap ChromeOS tablet -- can run debian in a container
by D. Hugh Redelmeier 24 Jan '22

24 Jan '22

https://forums.redflagdeals.com/lenovo-canada-chromebook-10e-tablet-129-les… This is $129 tablet seems to be aimed at kids in schools. It's not particularly powerful, but it has a nice screen (1920x1200, 400nit), battery, and a solid build. This version of ChromeOS invites you to create a container with debian in it. The debian is from the debian repos: not customized. I've done so. I can run xterm, but it is awkward without a keyboard and mouse. I've loaded gnome desktop but I'm not sure how to start it. I wanted to use gnome's on-screen keyboard. Seems like a fun toy for this price. The weakest point is that it has only 32G of eMMC (disk) and no slot for an SD card. It has only one USB port and that is used for power. I was able to use a USB-C hub with "power delivery" to add more peripherals. The sale might end at any time. Perhaps the end of the day or the end of the weekend.

5 9

RaspberryPi won't automount USB memory stick
by Kevin Cozens 19 Jan '22

19 Jan '22

Greetings, all. I have an embedded system that uses a Raspberry Pi 3. I have it set up and running with the latest Raspbian and all is well, almost. For some reason the Raspbian system is not set up to automount memory sticks when they are inserted in to a USB port on the machine. On another embedded system I needed to install the usbmount package to get the system to automount a memory stick when it is inserted. I have installed usbmount on the RPi but it still won't automount a USB memory stick. The output from dmesg reports that it is seeing the insertion of the USB memory device. The device is also reported under lsusb. Why is Raspbian not set up to automount a memory stick like is done on a normal Linux based desktop? My desktop does it and I don't have an usbmount package installed. How do I configure Raspbian to automount a memory stick? -- Cheers! Kevin. http://www.ve3syb.ca/ | "Nerds make the shiny things that https://www.patreon.com/KevinCozens | distract the mouth-breathers, and | that's why we're powerful" Owner of Elecraft K2 #2172 | #include <disclaimer/favourite> | --Chris Hardwick

5 7

Humble subscription service is ditching Linux after this month
by D. Hugh Redelmeier 17 Jan '22

17 Jan '22

I've never used it, so I don't know what I'm talking about. If you need to fetch anything from their server, do it now. <https://arstechnica.com/gaming/2022/01/humble-subscription-service-is-dumpi…>

2 1

X10 - Gear you don't want? Or replacement suggestions?
by Giles Orr 16 Jan '22

16 Jan '22

X10 ( https://en.wikipedia.org/wiki/X10_(industry_standard) ) isn't directly related to Linux, but this seems like the right group to ask about it ... I've been happily using X10 transmitters and receivers to automate switching lights on and off around my place for about two decades. These days that requires a USB-to-serial converter cable, but otherwise works just fine. X10 has significant limitations (unencrypted, local interference, very slow, one-way) but works well for the simple things I want it for. Which leads me to my two related but rather different questions. First Question: Does anyone have any X10 gear they'd like to get rid of? I'll happily take it off your hands. If you'd prefer to sell it rather than giving it away, we can talk. I'm particularly looking for a "Transceiver Module." I can still buy these from x10.com - but they're an American company without a Canadian customs broker. They'll happily ship me stuff ... but whether or not it arrives, how much I have to pay in duties, and whether or not I have to travel to Niagara Falls to pick it up ... all my problem. Second Question: What's a more modern replacement for X10? Keeping in mind that I have several limiting caveats. The first of which is, no "calling home." All interactions should happen within the confines of my computers and my residence. I would also fairly strongly prefer not to rely on a local wireless network: I have wireless, but it's deliberately off most of the time and I prefer it that way (for misguided security reasons, not misguided health reasons ... I like wires). I also don't want to have to do my own soldering (I'm capable of it, barely, but would prefer plug-and-go). Thanks. -- Giles https://www.gilesorr.com/ gilesorr(a)gmail.com

4 3

ot: perhaps, headphones?
by Karen Lewellen 14 Jan '22

14 Jan '22

Hi folks, or more specifically, a local store site where I can shop by details? Granted, some of this is tied to poor website design and accessibility. but I need to filter out what I do not need to reach what I do need, Regular wired headphones with a set of technical specifications. not bluetooth, not noise canceling, no microphone etc. Honestly, to avoid this issue I have been finding the same pair of JVC ones which, because they are well built, last a couple of years or more, smiles. To clear out the obvious best buy's site is no longer a possibility filter wise, and I cannot even get past the "are you human" thing at Walmart.ca, which has no way to answer it inclusively. Hoping to visit a place to pick up, rather than have to get them delivered..my office remains closed. Any ideas, even if only to narrow down specifics I can then ask about elsewhere? Thanks, Kare

10 29

cortex-m instruction set
by Trevor Woerner 12 Jan '22

12 Jan '22

Hey, i couldn't answer Hugh's question at this evening's meeting off the top of my head, but wikipedia to the rescue: https://en.wikipedia.org/wiki/ARM_Cortex-M#Instruction_sets "All Cortex-M cores implement a common subset of instructions that consists of most Thumb-1, some Thumb-2, including a 32-bit result multiply." I was much more involved with cortex-m SoCs in the earlier days but wasn't 100% sure of the instruction sets of the latest members of the family but, according to wikipedia, all cortex-m's use some variant of the thumb instruction set. Best regards, Trevor

2 1

OT RISC-V
by Ivan Avery Frey 11 Jan '22

11 Jan '22

Thought I would mention in the context of RISC-V, that the European Processor Initiative has created a Compiler Explorer website: https://repo.hca.bsc.es/epic There are two windows. The left window has the C or C++ source code and the right window has the RISC-V assembly output. Ivan.

3 4

[GTALUG-Announce] January Meeting Reminder
by Alan Heighway 11 Jan '22

11 Jan '22

*Speaker:* Chris Sullivan *Topic:* Radio Direction Finding with the Raspberry Pi *Date/time:* 2022-01-11 T19:30:00 *Location:* Virtual - Big Blue Button (link below) *Topic description:* Home-brew pseudo Doppler radio direction finding systems are typically based on discrete components. Much of the hardware complexity can be replaced with a software design, using minimal external components to the Raspberry Pi. This can dramatically lower the cost of implementation, provide additional signal processing capabilities, and provide remote control capabilities that permit the coordination of multiple units for instant triangulation. *We're going to use Big Blue Button for this meeting: * https://blue.lpi.org/b/eva-zjc-gjy-kgl *A*lan *H*eighway <http://heighway.ca/> heighway.ca VA3WAH / VA3YKZ [image: Please consider the environment before printing] --- GTALUG Announce mailing list announce(a)gtalug.org https://gtalug.org/mailman/listinfo/announce

7 8