TL’DNR

In this article I will look into the details of a special case with fully emulated systems, where an older Linux distro performs better than a new one. I will use RHEL7 and RHEL10 here, but the difference can also be seen with other distros. This is limited to the not very common case of the system running as a fully emulated environment, for example with QEMU. Most environments run virtualized guests instead.

What’s Morse Code?

Morse Code, also known as Continuous Wave (CW), is one of the oldest ways of electronic communication. You might also know the term from movies, when in emergency situations someone encodes Morse Code in hitting a pipe with a hammer, and someone else picks this up in listening to the sound transmitted by the pipe.

~40 characters get encoded into sequences of

• short dots, also called “dits”
• and longer dashes, also called “dahs”

For sending out morse code, one has to translate sequences of words/numbers into the matching sequences of dits and dahs. The length of the dahs is defined as “three times the length of a dit”. Also the spaces between the characters and between the words are defined, allowing the other side to pick up the transmission.

How it started

A friend owns rice paddies in Tochigi-ken, the district north of Tokyo where I live. Around the beginning of May, the rice planting is done. Since some years I attend the rice planting: initially going by train, and now for the third year by bike.

I can not go by bike right at the day of planting, it’s just to far. So I go to Utsunomiya, stay over night, and then at the day of planting go another 30km. My friend can just pin down the day of the event one week in advance, as weather should be good and a neighbor with special equipment needs to have time. As soon as I heard about May 3rd (a Saturday) would be this years rice planting, I started to lookup hotels.

With the right wing parties in Germany getting stronger, my Mastodon timeline gets posts from people considering to move to other countries, temporarily or forever. Japan is known for being peaceful, rich of culture, and is often called out as potential destination - so as a German living in Japan since 8 years, I will try to look at the relevant aspects. Maybe this sparks also others living in foreign countries to report?

Virtualization? Emulation?

What are these, after all?

• Virtualization in our context here means that when a guest operating system does computations, these get directly offloaded to the hypervisors cpus. One of the benefits is performance, one of the downsides is that the guests cpus need to exactly match the hypervisors cpus, or a subset.
• Emulation means that the computations are done in software. With this, host/guest architectures can be different. As a downside, this is slower than virtualization.

Using emulation, we can for example start a x86 based system, and then emulate completely different architectures like ARM or sparc64. How much performance does that cost us, how much power does this consume?

I’ve been living in Germany and Japan, let’s look at some aspects of the health systems.

Rundown of a typical doctor visit

I’m entering the doctors office at 10:30 on a weekday. The naming is already interesting: in Japan, the normal places where doctors investigate and treat patients are called clinic (クリニック), which sounds like the German “Klinik” - but in Germany these are big complexes to treat patients, so in English “hospitals”.

What’s this about?

Since a while I was wondering how to setup a chain of LEDs, where each LEDs colour and brightness could be assigned by me. In Germany I got 2 LED chains which turned out to just allow pre-programmed colours and blink patterns. I’m looking for full flexibility, so I could also for example deploy them behind the monitor and have them shine in the dominant colours of the current movie scene.

Note: I’ve taken out the IPv6 pieces here and moved them to a dedicated blog article.

Since the beginning of 2024, I run my own router. I’m using NTT flets GBit fiber as physical provider, and Biglobe as ISP ontop - other ISP’s do the IPv6 things differently. I started with 2 OpenWRT routers, after both of them went defective, I run the Star64 RISC-V board as router, with this functionality:

Choosing a monitor is hard! When you buy shoes, you try them out.. but you just know for real after wearing them for some weeks. We might see monitors at stores, or try to get advice from others - but everybody has different use styles, so it’s hard to decide for a model.

What I use the monitor for:

• working with multiple terminals, but not more than 3 or 4 on one screen. I heavily switch between virtual screens.
• I use webbrowsers, when these are in Japanese, I often have to increase the font size
• more rarely: watching a movie or a drama, or playing

The previous monitor

In 2016, when I came to Japan, I got a 27" monitor at Bic Camera, one of the huge electronic stores in Tokyo. This was an I-O DATA LCD-MF276XDB, introduced 2014, with ADS panel. Maximum resolution 1920x1080, refresh rate 60Hz, builtin speakers. I use the monitor heavily, but was looking for something new. At work, I got a Lenovo one, liked the 2560x1440 resolution, and more vivid colours.