Openhabian on ARM64

Hello everyone! The question is for openhabian maintainers.
I’ve recently bought a Pi 4 as a replacement for malfunctioning Orange 2e. Installed Openhabian and got a question. Why is openhabian still 32 bit? Pi4 is arm64.
BTW, serial port is disabled by default in openhabian image, i suggest you to change that. Quite confusing. Openhab is supposed to run autonomously, so it is very logical to have a serial console for troubleshooting

If I remember correct, there are performance issues if running 64bit Java versions on ARM64, therefore Java 32bit is recommended.

The underlying Raspian OS is 32 bit likely to support all the Pi models. If I recall correctly they are not all 64 bit.
You may find the answer on a Raspberry Pi forum.

Serial Port is for Serial communication. There is quite some hardware for Raspberry using the serial port.

In question 64bit, there is no benefit for openHAB (for now).

Lots of (Rpi) consumers have no clue what you are talking about :wink:

Is there any way to measure and compare performances?

This is my hardware running OpenHab 2.5 without any single issue with months of uptime. You can see system logs. Nothing. Its rock stable and runs few rules, manage Z-wave network … does the job.

It’s pure 64bit system and it uses this Java version:
openjdk version “1.8.0_222”
OpenJDK Runtime Environment (Zulu8.40.0.178-CA-linux_aarch64) (build 1.8.0_222-b178)
OpenJDK 64-Bit Server VM (Zulu8.40.0.178-CA-linux_aarch64) (build 25.222-b178, mixed mode, Evaluation)

Operations are rock smooth and CPU (with a small heat sink) runs with 30°C in closed together with other equipment.

UART0 usually represent a debug console. Probably also on RPi. On proper OS you can login via that console and fix things …

But UART1,2,3,… are used for general purpose comm. Agree.

But as the Raspberry has only one UART :wink:

According to these, the Pi4 has 5 accessible UARTs.

Oh, good to know. But as the openhabian image is not exclusive for Pi4…

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Its a bit more complicated, but I assume most of people doesn’t care. The underlying OS for Raspberry Pi VideoCore based platform is proprietary. It runs RTOS (recently purchased by Microsoft) which is AFAIK 32bit and have full control over ARM cores. Than one boots Linux kernel (which don’t know what is virtual, what is real hardware, what NSA backdoor … :slight_smile: ) and Debian like user land.

Upstream aarch64 Linux runs slower (then Raspbian based OS) and most of the interesting features simply don’t work with mainline kernel, some never will … + comments

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Either way, the underlying issues are upstream from openHAB.

Because there is absolutely no advantage in going with 64 bit, but some severe drawbacks.
Just as one example, using 64 bit registers/variables will consume twice as much memory.
And memory already is a premium on most RPi.

It makes sense not to provide a console on the serial port because that is often used for RF controllers (ZWave, ZigBee, 433 MHz and the like).
What you might consider to be confusing is preventing many people from messing up their OS config.
And no it is NOT logical to run the Pi off a serial console because it has HDMI for the purpose of attaching one. Or are you one of those folks to still have a VT100 hang around?


Yes, indeed. Memory consumption is little lower on 32bit OS. I completely forgot about that, but for running OpenHab instance 1Gb of memory should be enough in both cases.

When attaching RF controller such as popular RaZberry2 to your RPi, you have to alter hw config if you want to use it. Raspberry BT is using that UART by default.

According to official documentation UART0 lies out of the way of this and probably most of such hats … but I believe we can find some that does but since you already need to alter HW config for most popular ones, this becomes irrelevant.

It depends from the perspective. For people that work close with hardware or networks, VT100 is an essential tool. If you are a hardcore Linux persona and work with single board computers or micro controllers, you will certainly have UARTs in bulk and expect serial console to work OOB.

To me its logical that upper level software should in 2020 focus on Docker for deploying their work and not mess with an OS.

The DEC VT100 Series were only sold from 1978 to 1973. They are no longer manufactured and the company no longer exists.

I guess he’s about the protocol :slight_smile: not the hardware.

In fact, the serial console is a very common way to get access to a GNU/Linux computer, but it’s also true that the average GNU/Linux User today is not aware of this feature.
The most common way to get access to a headless system today is ssh.
Yes, this requires a working network connection (wether it is over ethernet or wireless), but also true: you shouldn’t connect the serial port with power on, and usually there will be no connection on the serial port. :wink:

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They probably are too young to understand the humour or even what a vt100 terminal was. I saw an educational opportunity.

What modern computers have an RS-232 serial port? The Pi only has USB ports. Dell was the last laptop I remembered with a serial port and they stopped making them several years ago.
We need to use RS-232 adapters to connect serially to some of our networking equipment.

So do I :slight_smile: but I have built my router on an APU 4B4, which has no video port at all and I used the serial port on my xen server to debug the router :upside_down_face:

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A few servers have serial ports but most are not USB only.
Most young’uns think USB is just for charging your entertainment device :rofl:


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Sorry, I forgot I have an advantage.
I work in IT at a University with many of our future leaders. :thinking: :scream:

I didn’t mention any standardised rack mount servers or PCs. There attaching a monitor to get to a console is a standard way. Many servers are also running a desktop. And one strange thing is that many servers have VGA console only, HDMI came here in last decade or so. Not a big deal but still.

  • a device that does something related to networking (router / switch) is almost certainly having a serial console. At least professional grade hardware that powers our/your main internet backbone
  • all SBC have UART on a dedicated header or via GPIO. I haven’t meet any without and usually is enabled by default.
  • most of TV boxes or NAS devices have UART at least marked on the PCB
  • and a bunch of (custom) industrial hw

Hardcore hw hackers should be able to attach a console also to mobile phone … :slight_smile:

If your UNI is social science oriented I believe there is certainly no need for this.

Our company IT department, which mainly do the HW purchases and installations, certainly have to know what this is. We have many serial consoles and console servers such as

In my time at university, we had a bunch of latest (at that time) terminal technology to connect to mainframe (VAX). IIRC it was this model: