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Quorten Blog 1

First blog for all Quorten's blog-like writings

Measuring the value of time outside of work, revisited

quorten

2021-01-16

Categories: personal-finance   home-network   covid19  
Tags: personal-finance   home-network   covid19  

Previously, I’ve raised the unanswered question. How do you measure the value of people’s time outside of working hours? The question of valuation inside working hours is easy: the hourly rate or salary is used to determine how much a specific labor task is valued at. But time outside of work, that’s a trickier value proposition. But, after thinking through first principles carefully, I have an answer.

So, let’s start with the basics. Labor outside the economic system.

  • A person can labor to gather natural resources.

  • A person can own resources, these are now considered “artificial” resources.

  • A person can labor to transform natural resources.

  • A person can labor to return resources to nature.

Here, the exchange is only between one person and the rest of the natural world, without respect to exchanges between persons. Now, exchanges between people can be classified as follows, still without the definition of money.

  • A person can gain a good or service from another person.

  • A person can loose a good or service to another person.

Read on →

Dirt cheap lossless video editing

quorten

2021-01-09

Categories: media-prog  
Tags: media-prog  

What is the simplest way to do lossless video editing on GNU/Linux? And, in particular, a workflow that works well for simple, cheap, low-budget movies? The technique is rather simple.

  1. Look at your video clips in a conventional video player, and create an ordered list of segments you want to include in the final output. Just use the filenames as-is in your list.

  2. Use my previous instructions on doing lossless video concatenation with FFMPEG.

  3. Now, use the LosslessCut video editor.

So, LosslessCut is a new name in town here, but its purpose is rather simple. It is a lossless GUI video editor that only supports trimming and cutting segments. Fortunately, that’s all we need for the final video editing step. If we want to copy segments or slice and transpose segments within a single clip, we can simply list the segments multiple times in the concatenation list and then just trim away all the extra video information. One great thing about LosslessCut is that it can export a CSV cut list, so you can build a precise command-line to rebuild your final output from the source input. Cutting apparently is restricted to keyframes, though, but hopefully that is good enough for most cuts.

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Ensuring systems are remotely accessible with watchdog timers and bootloaders

quorten

2020-12-23

Categories: home-network   raspberry-pi   reiterate  
Tags: home-network   raspberry-pi   reiterate  

I have written many times about watchdog timers, here I want reiterate all the important points that need to be properly implemented in regard to watchdog timers to ensure that systems are remotely accessible. Again, I reiterate, because this is important!

The idea, the primary goal here is to have a software setup that is robust enough to eliminate the need to have physical access to the computer in question in the event that problems occur and need to be fixed. Another goal is to be able to do so entirely through software using the conventional communications stack of a sophisticated booted operating system, without the need for adding special hardware to enable a reliable remote admin console. The practical means to this end entails the following requirements:

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EFI Boot Manager tricks

quorten

2020-12-23

Categories: unix   centos  
Tags: unix   centos  

Want to be able to remotely, non-interactively reboot a computer from an operating system installed on one disk or partition to another? With legacy BIOS boot, GRUB, and chainloading, this is easy: simply set the GRUB as your universal boot decision point, and you can change which menu entry is the default for boot. Yeah, sure, this works if you want to permanently make a change… but what if you only want to temporarily boot into one operating system, and on next boot after, boot to your main operating system? Well, there must be a way using grubenv and scripting, but that is a tricker proposition.

The latter case is especially useful if you think you might boot into an operating system in a potentially bad configuration, then need to use a watchdog timer to force a reboot into your known good operating system.

But, that is only partially to the main point of this blog article. How do you do this with UEFI? At first sight, UEFI looks to throw a monkey wrench in the way of the old standard, it’s much trickier to do bootloader chainloading with EFI boot. It’s actually quite simple once you look into the details. EFI has primitives to support everything you could want here directly. Because you can edit EFI variables from within the booted operating system, you do not need physical access to the machine to mess around in the “BIOS configuration” screens.

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Convert MBR partitions and legacy BIOS boot to GPT partitions and UEFI boot

quorten

2020-12-17

Categories: unix   centos  
Tags: unix   centos  

It is also possible to convert an MBR disk to GPT in-place and install the GRUB EFI bootloader after-the-fact. Be forewarned, however, that this is very tricky.

20201210/Google convert mbr to gpt
20201210/Google linux convert mbr to gpt in-place
20201210/https://serverfault.com/questions/963178/how-do-i-convert-my-linux-disk-from-mbr-to-gpt-with-uefi

20201210/Google grub install gpt partition
20201210/https://superuser.com/questions/903112/grub2-install-this-gpt-partition-lavel-contains-no-bios-boot-partition
20201210/Google grub install efi boot
20201210/https://askubuntu.com/questions/831216/how-can-i-reinstall-grub-to-the-efi-partition

Run all these commands as root.

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Boot CentOS 8 installer ISO with UEFI to install GPT partitions

quorten

2020-12-17

Categories: unix   centos  
Tags: unix   centos  

The CentOS 8 installer will not allow you to create GUID Partition Tables unless it is UEFI booted. By default, it is indicated as UEFI bootable via an MBR with an ESP, which means it must be written to an optical disc for UEFI boot. Although there is also a GPT, it does not properly indicate the ESP partition. And besides, most GPT tools expect the protective copy of the GPT to be at the end of the disk, not some other random location.

Fortunately, conversion to a bootable USB stick is easy.

Read on →

Workaround for minor issues in CentOS network installer

quorten

2020-12-17

Categories: unix   centos  
Tags: unix   centos  

Weirdly, the CentOS 8 network installer does not detect mirrors automatically. No worries, you can just specify it manually in the installer and everything will “just work” after that.

http://mirror.centos.org/centos/8/BaseOS/x86_64/os/

Oh, another thing. When selecting a destination disk to write to, every disk with installer files/partitions are detected on are removed from the available destination disks. So if you have an old installer on the destination disk, you need to wipe or else it won’t show up as an available option.

Philosophical principles of UEFI boot and Linux

quorten

2020-12-17

Categories: unix   centos  
Tags: unix   centos  

UEFI boot… ah, yes, the modern way of booting PCs. A reasonably sophisticated and professional boot standard, originating from Macintosh precursor technology like Extensible Firmware Interface (EFI) and Apple Partition Map (APM) is now brought to the PC world. UEFI boot and GUID Partition Table is glorious… or is it?

It’s not, unfortunately. Hindsight is 20/20. The reason why the sophisticated and modern boot standards worked so well on the Macintosh was because there was only one manufacturer of that kind of computer hardware. But, in the PC world, when you have many different manufacturers, each designing their own boot firmware, every little bit of complexity you add to the boot standard simply adds more margin of error. The “U” for “unified” does, in fact, give a head nod that it might be an oxymoron, and it indeed is!

If you want a sophisticated and complex standard of any kind, there must be only a single implementor in some sort of way, shape, or form, especially in the case of boot standards. Unlike web browsers, bootloaders are a very unattractive area of software development for rapid addition of features and enhancements. Matter of fact, quite the opposite: stasis is viewed as a feature in pre-operating-system computer boot. Traditionally, there was always very little to no information about bootloaders from third party sources, and UEFI is no different in that regard. If you want to learn about the boot sequence, there is pretty much only a very small number of technical reference documents that must be read in full. A search engine will not afford you any shortcuts here.

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Maximum safe temperature for LCD electronics?

quorten

2020-12-04

Categories: raspberry-pi  
Tags: raspberry-pi  

The printed circuit boards of modern electronics can stand up to quite high temperatures. They have to, because they need to survive the heat of the reflow soldering oven. Well… technically they only need be designed to survive that heat two or three times for a few minutes each time. But still, usually they still are mostly functional even when the sensitive components are pushed past those manufacturer-specified limits.

So, you have a modern mobile electronic device that you want to repair with heat? Yes, remove all batteries, both the main power battery and the CMOS clock battery, if present. But what about the LCD screen? We’ve been told many times that when it comes to working with heat and LCD screens, you’ve got to be careful because too much heat can damage the LCD screen. So, how much is too much.

Never fear, I can consult the official manufacturer datasheet I found for one of the LCD screens I use, found from this previous blog article. Combined with other info I’ve found on the Internet, I have a verdict.

20201003/https://datasheet4u.com/datasheet-parts/LTN154X3-L06-datasheet.php?id=672537
20201003/DuckDuckGo lcd hot glue temperature range
20201003/https://www.ifixit.com/Answers/View/463364/What+is+the+suggested+temperature+of+a+heat+gun+to+remove+the+screen
20201003/https://www.ifixit.com/Answers/View/251709/Which+Temperature+on+LCD+Separators+is+free+of+risks

Read on →

Interesting Digi-Key article about messy desks in electronics design engineering

quorten

2020-12-01

Categories: raspberry-pi  
Tags: raspberry-pi  

This Digi-Key blog article has some really interesting takes on the question of a messy desk for a design engineer. The messy desk fits the popular stereotype of the non-technical general public, but most of the time it leads to worse productivity, especcially when dealing with high-frequency circuits. Nevertheless, there are a few notable exceptions. The legendary analog design engineer Jim Williams who worked at Linear Technology was famously known for having a super messy desk? His response when asked about it? He likes to work that way, and besides, he found it discourages coworkers from “temporarily” borrowing tools off of his desk. Another interesting viewpoint on the caveats of having a super clean and organized desk in the corporate world, it can send subliminal messages to management that the engineering team is “almost finished.”

Oh, and the final thing in this article, it mentioned a quote from Albert Einstein. Paraphrasing, if a cluttered desk indicates a cluttered mind, what does an empty desk indicate?

20201201/https://www.digikey.com/en/blog/even-einstein-can-be-wrong