March 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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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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Help with choosing a WiFi router
by David Mason 02 Apr '19

02 Apr '19

We’ve had a DLINK DIR-628 for quite a while. When it works it has been great, but it drops out several times a day. Sometimes it come back fairly seamlessly, but sometimes you have to turn off the wifi on connected devices and turn it back on again. Power-cycling it always resolves the problem, but it’s annoying. So I guess I’m in the market for a new WiFi router. A little bit of additional range would be great, and if there’s more speed available, so much the better, but as I said, when it’s working, it’s been great. It’s not uncommon for 3 video streams being viewed while I’m ssh’ed into remote systems, or downloading files, or cloning repositories, and it all works fine. Price isn’t a major concern… I’d happily pay for reliability and performance. To the degree it matters, we’re mostly connected from Apple devices (except for the gateway and RAID servers - both of which are Debian - which are wired together). Thanks for any advice! ../Dave

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VM Virtualbox Linux
by R360 Design INC 01 Apr '19

01 Apr '19

Hello everyone, I have a VM virtualbox set up running CentOS Linux. The host OS is Windows 10. I then attempted to set up two-way network communication between the CentOS Guest and my Windows host. Has anyone attempted this and succeeded? I thought it would be straightforward but setting up the NAT adapter, and installing "VM Guest Addition" got me lost. Ultimately, I 'd like to have a Apache server running on my Centos Linux VM, and then access it using a client browser on my host machine. Regards, Jonathan

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Thanks for Who Mentioned the Markham Research Lab at IBM
by nick 31 Mar '19

31 Mar '19

Greetings All, I don't recall who mentioned the research lab in Markham but after going indirectly through HR they are trying to find work for me on their compiler or toolchain team up there at entry level. Thanks, NIck

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reverse engineering
by D. Hugh Redelmeier 30 Mar '19

30 Mar '19

Sometimes I get annoyed at binaries for which I don't have any code. Stepping back a bit, I get annoyed at undocumented hardware for which the only drivers are closed-source, or even worse, Windows-only or Android-only. One way to pry these open is through reverse engineering tools What prompts this message is that the NSA has just released Ghindra as open source. <https://www.nsa.gov/resources/everyone/ghidra/> (This would be perfect code for the NSA to plant a trojan horse in.) Previously (and maybe still) the tool that seemed to be most popular was IDA, a commercial product that runs on Windows. There are some other choices: <https://reverseengineering.stackexchange.com/questions/1817/is-there-any-di…> ==== War story (feel free to ignore): ==== I put some effort into this in the early 1980s. I wrote my own disassembler that made some inferences from control flow. I disassembled two non-trivial bits of code: - the undocumented monitor that resided in my Altair's "Bytesaver" (EPROM reader and writer). The software was originally written for the Processsor Tech Sol 20 machine. - the proprietary but buggy firmware in my Volker-Craig VC2100 terminal (meant to compete with the VT100) These were a lot of work and they were only 1k and 16k bytes respectively. My reversing was complete: I ended up with useful source for both. With information gained from the PT monitor, I was able to write my own, much more ambitious monitor. I found bugs and identified fixes for the VC2100 and reported them to the author of the code at Volker-Craig. But the product was cancelled before the fixes were released. I gave up on one reverse engineering task. I bought a copy of MuMath, a symbolic algebra package, that was for the Osborne I. I tried to run it on my Kaypro II. It seemed that there was some tricky copy-protection code involving bank-switching. I never cracked that puzzle. ==== End of war story ==== I would love to see better reverse engineering for a few things. - my Lenovo Yoga notebook gets a machine whenever it goes to sleep and back. Sleep/awake still works, but the machine checks probably slow things down and they make me unhappy. - nvidia video cards are not well-enough supported by nouveau. nvidia has not disclosed enough about the hardware to fix this. - Many GPUs used with ARM are not supported with open-source Linux drivers. There are a number of reverse engineering projects but progress isn't fast enough for me. My guess is that these projects are too hard since the size of object code to be analyzed is several orders of magnitude more than what I've tried.

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[GTALUG-Announce] GTALUG Meeting April 9th at 7:30pm
by hi＠gtalug.org 29 Mar '19

29 Mar '19

<https://gtalug.org/meeting/2019-04/> # Linux Unhatched Learning Circles at Toronto Public Library with Larysa Essex Toronto Public Library has adopted the learning circle model to deliver tech-based programs. This talk will illustrate how the model was used to deliver an online Linux course in a non-traditional classroom setting. ## 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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March 2019 meeting video
by Alex Volkov 28 Mar '19

28 Mar '19

Hey Everyone, March 2019 meeting video -- FPGAs for Fun, Acceleration, and Profit! with Chris Tyler Is here: Main talk -- https://youtu.be/VAdO16ER-GE Q&A -- https://youtu.be/aUsF1C-6w8Y Alex.

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[GTALUG-Announce] In The Community
by hi＠gtalug.org 26 Mar '19

26 Mar '19

# In The Community # March ## Toronto AWS User Group AWS Storage Options and their anti-patterns * Wednesday, 27th, 6:00 PM * Myplanet, 252 Adelaide St. E * https://www.meetup.com/Toronto-AWS-Users-United/events/258967292/ ## Toronto Perl Mongers * Thursday, 28th, 7:00 PM * FlightNetwork, 145 King St West Suite 1400 * https://www.meetup.com/Toronto-Perl-Mongers/events/rhsxwpyzfblc/ # April ## Polyhack Toronto * Wednesday, 3rd, 6:30 PM * H Bar, 859 Queen Street W * https://www.meetup.com/polyhackTO/events/259646709/ ## Unix Unanimous * Wednesday, 10th, 6:45 PM * Ryerson, 245 Church St. [George Vari Engineering Building], ENG201 * http://www.unixunanimous.org/ ## Serverless Toronto * Thursday, 18th, 6:00 PM * Myplanet, 252 Adelaide St E * https://www.meetup.com/Serverless-Toronto/events/259565019/ ## Achievers Tech Talks Keeping up with React: What's new in version 16 * Thursday, 25th, 6:00 PM * 190 Liberty St. * https://www.meetup.com/achieverstech/events/260063740/ *** If you have an event to add to this monthly list, please contact: scott [at] gtalug [dot] org. --- GTALUG Announce mailing list announce(a)gtalug.org https://gtalug.org/mailman/listinfo/announce

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Local source for weird RAM
by Mike Kallies 21 Mar '19

21 Mar '19

Hello GTALUG, I have an HP ML110 G6 which I'm using for some minor virtualization, but it has 12G of RAM in it. I've been looking how to bring it up to 32G, but the options have been risky and expensive. So much so, that replacing it with a different machine seems more worthwhile. Does anyone know a local source for these 8G "Dual Ranked, ECC, Unbuffered/NON-REGISTERED" modules? https://trainingrevolution.wordpress.com/2014/01/05/hp-proliant-ml110-g6-se… Or should I give up and buy a new machine? -- Mike Kallies mike(a)kallies.ca

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