May 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] MyRocks 101
by hi＠gtalug.org 10 Jun '19

10 Jun '19

<https://gtalug.org/meeting/2019-06/> # MyRocks 101 You may have heard about MyRocks, the new implementation of log structured merge indexing via RocksDB for MySQL But what is it? How does it work? What’s it good for? What is this thing called compaction? In this session we’re going to explore the high level mechanics as well as common system variables, column family options, and associated metrics so that you’ll have the familiarity you need for this emerging storage engine. ## 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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war story: fixing an LCD TV
by D. Hugh Redelmeier 07 Jun '19

07 Jun '19

My 39" UltraHD TV, the one that I used as my main computer monitor for almost four years, stopped working. The symptom was that it just would not turn on. The status light below the screen stayed red, meaning something like "standby". Normally it turns blue when I'm using it. Googling and watching YouTube videos convinced me that there was a chance that I could repair it. LCDs seem to have certain standard PC boards. - T-Con (timing control) - power supply - processor - LED light & video driver Replacement boards are reasonably inexpensive, apparently from chop shops (i.e. they buy broken TVs and sell the working parts). This shows someone fixing my model of TV. <https://www.youtube.com/watch?v=XD7rIEgYULI> >From my research, it seemed as if the most likely problem would involve the power supply module. I could get one for US$~20 + ~$20 for shipping. I opened up the monitor and examined the entrails. There was a burnt spot on the power supply board. I posted my problem to the BadCaps.com forum and got encouragement that a little bit of solder would fix the board. I tried this, and it worked. At least for now. I'm using the monitor to compose this mail. <https://www.badcaps.net/forum/showthread.php?p=898646> I spent several hours researching and perhaps an hour disassembling, soldering, and reassembling. It might not have been worth that time given the value of the monitor ($350 original price, but used for 4 years and obsolete). I find it satisfying to fix a hardware problem, even though I'm a software guy. Summary: not all hardware problems are hard.

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[OT] mySQL help
by Stephen 04 Jun '19

04 Jun '19

I am not on any lists for mysql. So I thought that I would ask her, Suggestions for a help list for mysql are most welcome. I have a LAMP for web site development and rarely need to touch the database admin stuff. It has been years. I am creating a new site with database but I can't get the user to have privileges. Can anyone spot what is wrong? So I connect to the server with: stephen@Avalon:~$ mysql -u root -p Enter password: Welcome to the MySQL monitor. Commands end with ; or \g. Your MySQL connection id is 11 Server version: 5.7.26-0ubuntu0.18.04.1 (Ubuntu) Copyright (c) 2000, 2019, Oracle and/or its affiliates. All rights reserved. Oracle is a registered trademark of Oracle Corporation and/or its affiliates. Other names may be trademarks of their respective owners. Type 'help;' or '\h' for help. Type '\c' to clear the current input statement. mysql> =========================================== I create grants mysql> grant all on rois3324_stephen.* to "rois3324_stephen"@"localhost" with grant option; Query OK, 0 rows affected (0.00 sec) =========================================== I try to see grants mysql> "rois3324_stephen"@"localhost" -> It looks like no grants were created. And I get a confirming error from PHP. Can anyone see what is wrong? Thank you! -- Stephen

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SSH Host tab completion
by Daniel Wayne Armstrong 03 Jun '19

03 Jun '19

Hello all ... I am currently running Debian Buster and Bash shell. I have a few Host aliases defined in my ~/.ssh/config. Example: Host test-server. So when, in console, I type ... $ ssh tes ... and hit Tab, then auto-completion fills out ... $ ssh test-server When I try to do the same thing in a terminal (urxvt), tab completion does *not* work. The complete host alias has to be entered. *But* tab completion for ssh host aliases *does* work if entered within tmux running in the terminal. Any idea how I can get tab completion working for ssh host aliases in the terminal? -- Daniel Wayne Armstrong https://www.circuidipity.com <http://www.circuidipity.com> Accomplish the great task by a series of small acts. -- Lao Tzu

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vim on Git
by 90ur1 90ur1 31 May '19

31 May '19

Couldn't stop from sharing a screenshot of this , while installing Git on Windows : "...for historical reasons ..modern GUI.. " Gouri [image: Capture.PNG]

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Intel Bay Trail bug fixed in 5.3!
by D. Hugh Redelmeier 28 May '19

28 May '19

Bay Trail is a family of processors/SoCs introduced in 2013. They were ubiquitous. And they suffered hangs under Linux. <https://ark.intel.com/content/www/us/en/ark/products/codename/55844/bay-tra…> The work-around has been to turn off some power-saving capabilities, crippling the usefulness of these "low-power" chips. (I suspect most users never found the magic incantation to do this and so have just given up on running Linux on these systems.) I'm subscribed to the bugzilla entries. I just got a notification of the thousandth comment added to one. A kernel patch has been submitted by Intel and accepted for 5.3 (months away). The whole useful life of this SoC has been impaired. This patch is work-around code for a chip bug. The patch itself is restricted to "Valleyview" which is a name for something that covers all Bay Trail chips, and only Bay Trail chips. <https://bugzilla.kernel.org/show_bug.cgi?id=109051> --- Comment #1000 from w2q(a)arcor.de --- I may cite Hans de Goede from this site: https://www.phoronix.com/forums/forum/software/mobile-linux/1096936-intel-b… " Actually the Intel open-source devs have been working on fixing this and a patch-series which should improve things wrt this has been queued for merging into 5.3 (it just missed the 5.2 merge window), see: https://cgit.freedesktop.org/drm-intel/commit/?id=a75d035fedbdecf83f86767aa… " Yeah, comment 1000!

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Ryzen 3 Specs for Chipset and other details
by nick 27 May '19

27 May '19

Greetings, I'm sure some of you already know but ryzen 3 was announced today. I don't know all the details but the most interesting things are: * Native PCI Express 4 and USB 3.1 on the chipset not sure about GEN 2 * 64 Core Data Center Processors with hyper threading I'm assuming so 128 threads * Not been tested externally but IPC per core similar to Intel This is a link to the discussion on motherboards: https://hothardware.com/news/amd-x570-ryzen-3000-zen-2-motherboard-roundup Seems to be a interesting product stack, Nick

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the meaning of Core i[3579] (was: NUC NUC NUC)
by D. Hugh Redelmeier 27 May '19

27 May '19

TL;DR: Intel uses brands. We care about technology. Sometimes brands map cleanly onto technology, but sometimes they don't. You cannot trust that mapping. | From: Lennart Sorensen via talk <talk(a)gtalug.org> | Yeah the i7 is becoming very inconsistent in gen 9. A few high end | ones have kept SMT, while the lower end ones don't have it, but the core | count has gone up instead. I believe all i9 chips have SMT. Here's my inference on the matter (not based on careful research): - these names are brands, not technology - we (techies) want them to represent technologies. For example, we kind of know what "Core i5" means - when times are good, and changes are smooth, intel tries to align its brands with technologies - when Intel is desperate, they muddy the waters of their brands Example trajectory: - Pentium meant one thing. - Then it got extended with the II and III branding AND technologies. Still related, and the branding evolved in a coherent way - Then the Pentium 4 came along and it was something completely different - Pentium M was also technically different, but that was signified by a sufficiently different name (in my perception) - "Pentium" lay dormant for a bit, and then got attached to some Atom-architecture and low-end (crippled) Core chips. Talk about confusing! It became a pricing / value designator and not a technology. Intel is in trouble. It's latest fab processes (10 nanometer) are not coming on stream as quickly as they had planned and promised. Historically they have been significantly ahead of other fabs. Now they are behind and squirming visibly. This has thrown their whole roadmap off. The i9 seems to be a way of showing forward motion without needing the new fab processes. A way to appear to "refresh" their line without stressing their manufacturing capabilities. As far as I recall, they do have one 10nm product that they claim is shipping but it's not very good and so probably nobody is buying it. It is probably so expensive to produce (low yields) that they don't want anyone to buy it. It's a mobile chip without a GPU (probably due to yield issues) that isn't notably better than the normal 14nm versions that are shipping. Since 10nm isn't productive, they are shipping as much 14nm product as they can make. But it's not enough for the market. They didn't build up 14nm capacity because they thought they would be using 10nm fabs. Intel also has AMD as a competitor and threat for CPUs, something they could ignore for a long time. The upcoming "Rome" AMD server chip looks to be particularly scary. AMD is selectively using TSMC's 7nm technology (apparently comparable to Intel's 10nm -- don't get fooled by the number). In the eighth generation of Core, they moved some extra cores and HT down to lower-numbered models, probably to ward off the mild AMD threats. Perhaps to stimulate consumer excitement. In my mind, this happens to make the i5 a "sweet spot". And make the 8th gen fairly attractive (up until now, I've been content sitting at the 4th gen). But maybe the next one will better deal with the speculation problems. Don't count Intel out. Their server chips were inferior to AMD's Opterons for a long period but the server market didn't significantly switch to AMD. Then Intel technology caught up and surpassed AMD. ================ The term "microarchitecure" is used to describe how a chip is organized. The Core "microarchitecture" started with the Core 2 Duo branding. The "Core" branding before that had a different microarchitecture (32-bit). So confusing. Intel's current Core-brand processors (and XEON-brand too) are still based on an evolved Core microarchitecture. AMD's Zen microarchitecture is newish, and it is what has put them back into the game. When I talk about "Atom", I'm refering to microarchitecture. The branding of those products is way too hard to follow.

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Ontario Bill 72: "Right to Repair"
by D. Hugh Redelmeier 26 May '19

26 May '19

This is a private member's bill so it is unlikely to pass. <https://www.cbc.ca/news/technology/what-on-earth-newsletter-right-to-repair…> <https://www.ola.org/en/legislative-business/bills/parliament-42/session-1/b…>

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