January 2019 - Talk - lists.gtalug.org

war story: power failure makes CentOS system unbootable
by D. Hugh Redelmeier 30 Sep '22

30 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.

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[GTALUG-Announce] GTALUG Meeting Feburary 12th at 7:30pm
by hi＠gtalug.org 11 Mar '19

11 Mar '19

<https://gtalug.org/meeting/2019-02/> # FPGAs for Fun, Acceleration, and Profit! w/ Chris Tyler Field Programmable Gate Arrays (FPGAs) have moved from being expensive, exotic prototyping tools to affordable mainstream devices for hardware customization and acceleration. This talk takes a general look at FPGAs, how to use them, the current technology landscape, the increasing use of FPGAs as cloud, leaf, and server accelerators, and related technology initiatives around standardization and cache coherence. ## Location George Vari Engineering and Computing Centre 245 Church Street, Room 203 Ryerson University <https://goo.gl/maps/16oJ2> <https://www.openstreetmap.org/way/23447525> ## Schedule * 6:00 pm - Please discuss on the general mailing list (i.e. <talk(a)gtalug.org>) where you want to go for dinner. * 7:30 pm - Meeting and presentation. * 9:00 pm - After each meeting, a group of GTALUGers move to The Imperial Pub (54 Dundas St East) for refreshments and more socialising. # Code of Conduct We want a productive happy community that can welcome new ideas, improve every process every year, and foster collaboration between individuals with differing needs, interests and skills. We gain strength from diversity, and actively seek participation from those who enhance it. This code of conduct exists to ensure that diverse groups collaborate to mutual advantage and enjoyment. We will challenge prejudice that could jeopardise the participation of any person in the community. The Code of Conduct governs how we behave in public or in private whenever the Linux community will be judged by our actions. We expect it to be honoured by everyone who represents the community officially or informally, claims affiliation or participates directly. It applies to activities online or offline. We invite anybody to participate. Our community is open. Please read more about the GTALUG Code of Conduct here: <https://gtalug.org/about/code-of-conduct/>. If you have any questions, comments, or concerns about the GTALUG Code of Conduct please contact the GTALUG Board @ <board(a)gtalug.org>. --- GTALUG Announce mailing list announce(a)gtalug.org https://gtalug.org/mailman/listinfo/announce

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Pine Book Pro
by Alex Volkov 04 Mar '19

04 Mar '19

Hey Everyone, It looks like Pine64 are releasing Pinebook Pro, a laptop that I'm actually willing to pay money for and then use. https://forum.pine64.org/showthread.php?tid=7093&pid=43850#pid43850 Specs: * 14" 1080p IPS LCD panel * 64/128GB of eMMC storage* * Black magnesium alloy body * SD card slot * Digital video output via USB-C up to 4K60hz * Audio aux out / UART * USB 3.0 and USB 2.0 ports * 802.11ac WiFi * Bluetooth 4.2 * 4GB of LPDDR4 RAM * Charging via barrel port or USB-C * Rockchip RK3399 ; big.LITTLE Hexacore A72/A53 SOC * 2mpx front-facing camera * Microphone * Speakers * Slim and slick design with minimal branding * PCIe x4 that can take a m.2 NVMe SSD using an optional adapter * Target Price: $199 Looking on the picture the things I like: * Regular keyboard with thick keys and minimal amount of weirdness (the location of 'Delete' button is questionable, but I'll live with that. * 1080p IPS scree should be pretty nice * NVM.e slot At least I can definitely replace my acer chrome book 11, which works when I need a very light computer in a pinch to dump video from my camera or browse the web, but not much else. I'm hoping that the product would be successful enough that there's going to be a release of a version with 8GB of RAM -- that would put it on par with ultrabooks. Thought I don't think Pinebook Pro ever going to meet its $200 US target price. Thoughts? Alex.

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Sendmail Changes
by Chris Tyler 30 Jan '19

30 Jan '19

I have a very old sendmail configuration on a VM on a dying server. I need to move it to a stable hw platform, so I took the sendmail setup and migrated it to a new system with a current Sendmail installation. The previous Sendmail configuration worked fine and was trusted by remote senders. It did not have SPF, DKIM, or DMARC set up. The new Sendmail server worked fine (worked as expected), but was not trusted by some remote MTAs sending TO it - including those used by Google/gmail. This seems odd because the only real difference between the two configurations is the Sendmail version -- something seems to have changed in the software. I reverted to the original system after these experiments last summer, but haven't circled back to it until now, when the failure of the underlying hw is forcing my hand. I haven't been following the evolution of Sendmail. I need to set up a better long-term solution (possibly with another MTA, and definitely with SPF+DKIM+DMARC), but in the short term I urgently need to migrate this configuration over to a box that isn't failing. Is anyone aware of Sendmail changes (either in behavior or defaults) that would explain how remote servers regard the MX? Thanks-- -Chris Tyler

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google news alternatives?
by Karen Lewellen 25 Jan '19

25 Jan '19

Hi folks, Late new year wishes all around. I ask the question because I believe? someone posted a list of service alternatives a while back. Up until late December I was using theoldgnews.com Apparently google discovered the service though. Anyone know of a comparative alternative? Cheers, Kare

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How to run script at bootup in Debian
by William Park 23 Jan '19

23 Jan '19

Hi all, I need to run a custom script at the later stage of bootup in Debian 9.5 (board is BeagleBone Black). I seem to remember "rc.local" long ago, but it's gone in the latest Ubuntu and Debian. Online search says (1) simply create "/etc/rc.local", and systemd will automatically pick it up. (2) use crontab, "@reboot ..." Which is "proper" way in Debian world?--William

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nmcli is rather pleasant with tab completion
by Scott Sullivan 21 Jan '19

21 Jan '19

This morning I was in a scenario where just done an install (Fedora 29 Server), and the device had no wired network, only wifi. I was feeling lazy and didn't want to pull out my USB ethernet dongle and a cable. So out of curiosity, I was wondered how far I could get with the new nmcli (Network Manager CLI) tools, and tab completion. The answer, all the way to working wifi networking. So I thought I'd share the FYI. I see this coming in really handy for Raspberry Pi 3/3+ and Zero-W owners. Example output: [root@dna ~]# nmcli device wifi list IN-USE SSID MODE CHAN RATE SIGNAL BARS SECURITY ItsAWifi Infra 6 195 Mbit/s 100 ▂▄▆█ WPA2 * The_Terrace Infra 149 405 Mbit/s 97 ▂▄▆█ WPA2 ItsAWifi Infra 36 405 Mbit/s 94 ▂▄▆█ WPA2 -- Infra 153 540 Mbit/s 69 ▂▄▆_ WPA2 N.InetSamura_5G Infra 153 540 Mbit/s 69 ▂▄▆_ WPA2 AC.InetSamurai_5.825GHz Infra 165 195 Mbit/s 65 ▂▄▆_ WPA2 [root@dna ~]# nmcli device wifi <tab><tab> connect help hotspot list rescan [root@dna ~]# nmcli device wifi connect 00:19:BE:1E:C6:18 3C:17:10:22:AE:1E 80:2A:A8:18:2E:52 AC:84:C9:FD:27:95 BC:4D:FB:E2:8D:E8 The_Terrace 24:F5:A2:77:89:D3 6C:19:8F:C5:12:D8 A6:84:C9:FD:27:95 B4:75:0E:3F:CC:9E BELL270 ItsAWifi [root@dna ~]# nmcli device wifi connect ItsAWifi <tab><tab> bssid hidden ifname name password private wep-key-type [root@dna ~]# nmcli device wifi connect ItsAWifi password ***** And that worked! Best part, it also created all the needed files in /etc/sysconfig/network-scripts/ for this network, set to start onboot even! Very handy. -- Scott Sullivan

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Looking for Someone to Answer some Questions
by nick 18 Jan '19

18 Jan '19

Greetings All, It was nice to meet you guys this week as I use to go to GTALUG when I was in high school but been busy for the last several years. I was wondering as I'm still in school if anyone knows of people who actually work in compiler design or embedded systems in the Toronto/GTA area. The reason I'm asking is maybe it's just me but it's very hard to find people in Toronto. I'm aware of the mailing lists for a lot of the projects so it's more of a local thing. Thanks, Nick

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Re: [GTALUG] Looking for Someone to Answer some Questions - the python fork
by Stewart Russell 16 Jan '19

16 Jan '19

On Tue, Jan 15, 2019, 08:13 Alvin Starr via talk <talk(a)gtalug.org wrote: > > > It may be old but if the description of the memory footprint is correct > then it looks to be the smallest implementation which has some value in > memory constrained applications. > IIRC PyMite (another name for this project) was a subset of the Python 2 language and had to be fed special bytecode. It wasn't an interpreter of any form of Python we'd recognize. It hasn't been actively developed for a decade. While MicroPython/CircuitPython is much bigger (smallest system that's useful would be a 256 K flash/32 K RAM Cortex-M0) it's a fair subset of Python 3 with REPL and library support. The best value is definitely on ESP8266 boards, where you get a fully wifi-capable embedded appliance for under $5. MicroPython runs on many targets, including generic Unix and even bare-metal on a Raspberry Pi Zero. Stewart

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Re: [GTALUG] Looking for Someone to Answer some Questions
by nick 14 Jan '19

14 Jan '19

On 2019-01-13 7:55 p.m., Alvin Starr wrote: > On 1/13/19 1:22 PM, nick via talk wrote: >> >> On 2019-01-13 11:25 a.m., D. Hugh Redelmeier via talk wrote: >>> | From: nick via talk <talk(a)gtalug.org> >>> >>> | I was wondering as I'm still in school >>> >>> What school? >> I'm at Seneca but I also asked UoT students and for whatever >> reason most students are going into web so that's the assumption >> or mobile. Which is fun considering that's been pushed into the >> Co-op program. I'm not complaining it's also pretty easy to tell >> from the electives as well i.e. there is only one Linux System >> Programming course. Even if I look at Waterloo there are courses >> in this but off the top of my head, only a handful at least at >> the undergraduate level. > > If your interested in compiler design go and grab a copy of Aho and Ullman's book Principles of complier Design (ISBN 0-201-00022-9) > > Another one is the Turing Programming Language.(ISBN 0-13-933136-0) > > You could also try tracking down ACM POPL articles. > > A bazillion years ago I worked on compiler and language implementation for a Markham computer company. > > Finding people building production compilers will be hard. > > You forget to CC this list. Anyhow here our my other comments. It's not hard online but finding them in person is difficult. Thanks for the book recommendation through, seems it may be good to read the theory too. The GCC folks already gave me a list of Todos to get started. Frankly I've been busy with other work mostly with the X.org Foundation. >>> | if anyone knows >>> | of people who actually work in compiler design >>> >>> Compiler design: not a big field. Most compilers that take a team are >>> already designed. >>> >>> There is a group at the IBM Toronto lab that works on their compilers. >>> I've known a few of them, but my main connections have retired. >>> >>> An interesting snapshot of this area is the annual CASCON held in >>> October (free! with lunches!). >>> >> That's useful thanks for the heads up. I will probably try and go, >> have family in Markham. As for compilers I was talking gcc/clang >> work not older tech i.e. optimizations or other things related. > > GCC is something like 20+ years old and although is it still a very good language stack. > > LLVM and Clang are newer but I have kind of fallen out of tracking the various compilers . > > >> >>> | or embedded >>> | systems in the Toronto/GTA area. >>> >>> Lots of folks do that. I don't know how to find them (I haven't >>> looked). They are often more embedded in the application area than >>> the computer field. (It often shows in the quality of their code.) >>> >>> I could imagine that networking through your school would help. >> See the above reasons. I tried too, but seems I'm on my own, > > I was under the impression the Seneca had a strong Open Source community. > > https://wiki.cdot.senecacollege.ca/wiki/Main_Page. > I did try going through CDOT but it's more web development and very little low level. The lowest level I'm aware of is porting packages to the ARM64 architecture but that's it. > If your interested in embedded systems then some hardware courses would go a long way to getting you somewhere because with embedded systems your almost always working directly with hardware. > I'm aware of the issues from a theoretical perspective just not actually running in on a embedded board.I have some Intel Board lying around and should figure out how to port a Linux distribution to it with a application stack using Yocto but again I'm frankly swamped with GCC and other things. Thanks and thanks for a notice about the IBM compiler lab from Hugh, Nick > >> >> Nick >>> --- >>> Talk Mailing List >>> talk(a)gtalug.org >>> https://gtalug.org/mailman/listinfo/talk >>> >> --- >> Talk Mailing List >> talk(a)gtalug.org >> https://gtalug.org/mailman/listinfo/talk >

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