March 2018 - 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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Build critique request and the story behind it.
by Russell 19 Apr '18

19 Apr '18

This year I purchased an APC UPS because of my flakey connection to the grid. Ominous read clicks coming from my boot drive cemented that decision. I am happy to say that not only did I avoid my biannual unexpected shutdowns, the UPS also sensed transient RF spikes. It begins to click, switching to the battery and back to mains, even though there is no visible disruption to service, although the emergency lighting in the hallway was triggered and beeped itself on. I decided to purchase a case and build a new desktop. I waited till now because I was loosely following Sarah Sharp, of Intel and listened to her comments on USB. Version 3.0 is RMA as of Jan this year and her general comment is that hardware development has peaked and so the immediate future is in developing software. Here is the case I chose. I take delivery tomorrow. http://www.coolermaster.com/case/lan-box-haf-series/haf-xb-evo/ Newegg has this combo on offer. Intel Core i5-7500 Kaby Lake 4-Core 3.4 GHz CPU w water cooling unit ASUS STRIX H270F GAMING MB G.SKILL 2 x 8G DDR4 As a creative anachronist or purposefull recycler, I haven't built a complete system from all new parts in a dozen years. I thought I'd get my hand in before arthritis takes over my hardware chops completely. I'd appreciate any warnings and caveats regarding this combo. I'm still window shopping but what I'm looking for is stability and longevity over gaming. This combo has DDR4 and USB 3.1. I'm kind of fixed on the usb but I'm not married to the ram. So suggestions which lower the cost are most appreciated. I have a 650w Corsair p/s which is ok but a big factor for me is the ambient noise and recommendations on a quiet supply would be appreciated. Noise is why I'm trying out water cooling. From the reviews on the case I'll probably have to replace the case fans, but who knows I might get lucky. I follow with interest the posts on UEFI, secure boot, SElinux, USB, udisks, udev, mobile linux and systemd. Now is my time to see if I have learned anything. Thanks to all posters. Regards -- Russell Sent by K-9 Mail

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PC build recommendation
by Alex Volkov 04 Apr '18

04 Apr '18

Hey everyone, I'm assembling a computer and I'm looking for some feedback. The computer I'm building I'll use for development, run some VMs, edit video time-to-time. I also already have a 1Gb hard drive which I plan to use for VMs. One of the big requirements is to be small size, lots of memory (eventually upgrade to 32GB) and have a somewhat beefy CPU (Thus Ryzen 2400G). I've chosen Asrock AB350 mini ITX because it's small and it's got dual HDMI. I'm thinking maybe I can reduce some specs to save a few bucks. Thanks, Alex. PCPartPicker part list: https://ca.pcpartpicker.com/list/Z6Rttg Price breakdown by merchant: https://ca.pcpartpicker.com/list/Z6Rttg/by_merchant/ CPU: AMD - Ryzen 5 2400G 3.6GHz Quad-Core Processor ($209.99 @ Memory Express) Motherboard: ASRock - AB350 Gaming-ITX/ac Mini ITX AM4 Motherboard ($142.75 @ Vuugo) Memory: G.Skill - Ripjaws V Series 16GB (1 x 16GB) DDR4-3200 Memory ($219.99 @ Newegg Canada) Storage: Crucial - MX300 275GB M.2-2280 Solid State Drive ($104.00 @ Mike's Computer Shop) Case: Antec - ISK 300-150 Mini ITX Desktop Case w/150W Power Supply ($96.99 @ PC-Canada) Total: $773.72 Prices include shipping, taxes, and discounts when available Generated by PCPartPicker 2018-02-26 19:26 EST-0500

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Stealthy Stealing Bitcoins - jumpering the fence
by Russell 30 Mar '18

30 Mar '18

Heres another prime and probe issue. SGX was supposed to be fencing itself against associated timing attacks. According to this article and its backgrounded links, a hypervisor can leak information to itself by compromising branch prediction units and using "near field" affected border timing exploits. https://www.theregister.co.uk/2018/03/28/intel_shrugs_off_new_sidechannel_a… -- Russell

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USB-C/3.1 Video and Linux
by Giles Orr 30 Mar '18

30 Mar '18

A couple days ago I got a Best Buy flyer, and they have this item: https://www.bestbuy.ca/en-ca/product/asus-zenscreen-15-6- fhd-60hz-5ms-gtg-ips-lcd-monitor-mb16ac-dark-grey/10737845.aspx? It's a portable IPS LCD screen from Asus. I have a similar item from about three years ago that has two connectors, one for USB power-only and the other for VGA/HDMI. There were other models at the time that used only one connector, USB for both data and power - but that required a driver (and would have been painfully slow if it was USB2). But now here's this new model: it's one connector only, USB-C. And presumably USB3.1. And USB3.1 can carry video. But at this point I get lost among the standards and their implementations and which one supports what. I have an Asus Zenbook (it's Linux-only at this point) that has a USB-C connector, but I suspect it's USB3.0. So the first question is: how do I check that? Second, does Linux support video-over-USB3.1? Do I need a special cable? Is this "Thunderbolt?" How can I check if my machine would support this? I admit that I'm probably not going to run out and buy this tomorrow as the old one is mostly sufficient for my needs, but I'm very curious about the state of Linux support for USB3.1 and Thunderbolt's many features. And I'd like to know if my USB-C port supports USB3.1. Thanks. -- Giles https://www.gilesorr.com/ gilesorr(a)gmail.com

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New Deaktop PC -- To Run debian Linux - PCPartPicker Recipe;
by Steve Petrie, P.Eng. 29 Mar '18

29 Mar '18

Greetings To GTALUG, At long last I have created a final build recipe for my new desktop PC to run debian Linux. Replacing an ancient Dell PC running WIndows XP: a.. https://ca.pcpartpicker.com/user/Steve_Petrie/saved/#view=krFNNG The configuration is an Asus LGA1151 socket motherboard with Intel i5-6500 CPU and 16 GB DDR4 memory.. A dialup modem remains to be added: US Robotics USR5637 V.92 USB Faxmodem Comments welcome. * * * * * * My plan is to be ordering the parts by Friday 30 March or or Monday 2 April at the latest. The HP PS/2 keyboard and HP PS/2 mouse are already ordered (from PC-Canada) but that order is still on hold, pending addition of items to the order.. Steve

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Re: [GTALUG] New Deaktop PC -- To Run debian Linux - PCPartPickerRecipe;
by Steve Petrie, P.Eng. 29 Mar '18

29 Mar '18

Many thanks to so many responders impossible to mention all individually !! Have duly noted around a half-dozen configuration items of the build recipe, for review and no doubt at least some already for revision. All postings greatly appreciated ... Steve

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cheap colour printing with a privacy issue
by D. Hugh Redelmeier 27 Mar '18

27 Mar '18

<http://forums.redflagdeals.com/amazon-ca-hp-envy-4520-wireless-all-one-prin…> This is a scanner + printer device. Apparently with Linux support via HPLIP. It costs as little as $33.52 + tax through Amazon Warehouse deals (customer returned units, I think). If you manage to add something to your order to reach $35, you qualify for free shipping. This device is qualified for free ink for life at the rate of 15 pages per month. These are not just nominal pages (i.e. with 5% coverage), they are any pages (eg. prints of photos). The major downside is that the printer must be allowed to contact HP at all times through its wireless and your internet connection. What is it sending to HP? HP tries to address these concerns but they didn't satisfy me. Could Bad Guys hack this channel? Reluctantly, I think that I'll pass on this bargain.

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I'm now officially working for Index Exchange, and we're officially hiring
by David Collier-Brown 26 Mar '18

26 Mar '18

There's a dev position posted at https://boards.greenhouse.io/indexexchange/jobs/626598?gh_src=pcqt311 and a full list of positions attached to it Currently we're up near the Allen expressway, but we're moving downtown some time later this year, and have jobs in Waterloo and Montreal as well. --dave -- David Collier-Brown, | Always do right. This will gratify System Programmer and Author | some people and astonish the rest davecb(a)spamcop.net | -- Mark Twain

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Booting Fedora from M.2 Optane Nvme
by Russell 19 Mar '18

19 Mar '18

With all the CPU cache fencing going on I thought it might be fun to fiddle with NVM express on Fedora 27. My primary SSD on this z370-A, was/is in build limbo while I updated bios and waited for outcomes. I installed a 32gib module from Newegg ($90 delivered) and I booted from F27-workstation live on usb. I let the anaconda installer do the automatic partitioning. 5gib of the 32gib reported was left unallocated for over-provisioning. First boot appeared to be twice as fast as on the SATA SSD. Three or four seconds to get to the gui login as opposed to 7 or 8 on the original drive. Had to install hdparm from the repo. # hdparm -tT --direct /dev/sda1 /dev/sda1: Timing O_DIRECT cached reads: 930 MB in 2.00 seconds = 464.92 MB/sec Timing O_DIRECT disk reads: 1370 MB in 3.00 seconds = 456.30 MB/sec # hdparm -tT --direct /dev/nvme0n1 /dev/nvme0n1: Timing O_DIRECT cached reads: 2302 MB in 2.00 seconds = 1151.84 MB/sec Timing O_DIRECT disk reads: 3474 MB in 3.00 seconds = 1157.65 MB/sec More info on Nvme with a nice diagram of the Linux storage stack here. https://en.m.wikipedia.org/wiki/NVM_Express I switched back to the original SSD. An os-probe mapped the device to /dev/dm-1 and I was able to remake grub.conf and add this install to the bootloader on that drive. A couple of switches back and forth between drives and it looks like the 10% performance hit I had experienced after the microcode updates, is now somewhat reduced, +-5%. Guilding the lilly a bit, as I didn't have any day to day problems with performance. Although it's hard to name Intel's product actions around this issue a field of Lilly's. -- Russell

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