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Today, the editor will share with you the relevant knowledge points about the Linux release of the Internet of things. The content is detailed and the logic is clear. I believe most people still know too much about this, so share this article for your reference. I hope you can get something after reading this article. Let's take a look at it.

What is a Linux distribution (Linux Distribution)?

Linux is an operating system: this program is the core of controlling the computer. It decides how to divide available resources (CPU, memory, disk, network) among all other programs competing for it. Although the operating system is very important, it is of no use in itself. The purpose is to manage the computing resources of other programs. Without these other programs, the operating system cannot achieve many goals.

This is the source of the distribution. The distribution provides many other programs that, along with Linux, can be assembled into the working set for a variety of purposes. These programs range from basic programming tools, such as compilers and linkers, to communication libraries, to spreadsheets and editors, to almost everything in between. Distributions tend to have supersets that are actually used by each computer or solution. It also provides many options for each category of software components that users or companies can combine into what they think is a working set. It can be roughly compared to a supermarket, where there are many items to choose from on the shelves, and every user can choose items that are meaningful to them from the shopping cart.

Binary-based distribution or source-based distribution?

Distribution can be broadly divided into two categories: binary-based and source-based.

The binary-based distribution provides all the software components that have been precompiled and ready to be installed. These components are compiled with "good enough" build options, which work fine for most users. They do provide resources for a small number of users who need or want to compile their own components. This distribution is reflected in Debian,Fedora Core,OpenSUSE,Ubuntu and many other versions. Although they provide the same type of system, they all use different methods (unfortunately, incompatible) to do so. They are the main distribution methods used in general-purpose computers such as servers, desktops and laptops.

Source-based distributions, on the other hand, focus on providing a framework in which end users can build all components from source code. These distributions also provide tools to easily select a reasonable starting collection of components and adjust the build of each component as needed. These adjustments can be as simple as adding compilation flags to use different versions of the source or modifying the source in some way. Users will assemble a menu they want to build and then start building. In a few minutes or hours, depending on the situation, they will get a system software that can be used on their computers. Examples of such distributions are Gentoo, Android, and Yocto.

In general, these source-based distributions are usually preferred for embedded Linux-based devices, especially IoT devices. Although they are difficult to set up and maintain, source-based distributions have the unique advantage of customizing installed images according to the actual target hardware to maximize resource utilization or minimize resource waste. For embedded devices, this is often a powerful constraint. In addition, source code-based distributions are more suitable for cross-builds (where the computers on which the platform is built are different from the computers running on them), while binary-based distributions are more suitable for self-managed builds. You build and run on the same machine (or the same architecture).

Given the widespread use of Intel architecture machines as build machines and the use of ARM architectures for IoT products today, cross-build support is critical for IoT devices.

Container-centric distribution

The traditional Linux approach only provides a single unified user space for all platforms outside the kernel. The new model is about composing user space into a collection of "containers". The containerization model converts a part of the user space into a federated collection of components, each of which is highly independent.

Containerized linux distributions bring many benefits, from allowing teams to work more independently to making fine-grained platform upgrades possible. The disadvantage is that they take up more space than non-containerized solutions. However, if the development of technology has taught us anything, it is that when the only disadvantage of a new technology is that it takes up space, its available resources tend to expand, making each generation of new problems smaller and smaller.

Here are some early options to compare with existing distributions.

Linux distribution of the Internet of things

Now, we must delve into the controversial areas. Many people have their favorite Linux distribution, and they stick to it even though their requirements have changed dramatically (for example, from server settings to embedded IoT devices).

I'll start with the following list: here are some examples of mature Linux distributions and some up-and-comers. There are many other existence that may be more suitable for some use cases.

1. Yocto

Yocto (https://www.yoctoproject.org/) is a source-based distribution that has been used in many embedded and IoT devices. It attempts to combine the benefits of a binary-based distribution (for example, explicitly separating the package and its dependencies) with the benefits of a source-based distribution. the latter allows you to change the target binaries in a significant way when making minor changes.

Yocto consists of a series of recipes (recipes), each of which describes how to build a module of the system (for example, libraries, daemons, applications, etc.). These recipes are then collected into layers that collect a range of recipes and configure aspects of how they should be used together, from compilation flags to recipe functions to details about how they appear on the target. Each target build will consist of some of these layers, each of which adds or removes packages or modifies its default behavior in the lower layers. This allows multiple parties to adjust their own binary images to affect the final software. Therefore, if the base layer uses a conservative set of compiler flags (which is usually done), chip vendors can add compiler flags that benefit their specific chip models, while motherboard vendors can remove chip functions that their motherboards may not support.

For your Internet of things products, this actually means that your effort to build a solution using a motherboard that already supports Yocto will be to add or modify formulations to provide added value to basic functionality. You also need to have a build and configuration management infrastructure setting that allows you to create images for your goals, although in today's container world, this is not difficult to do.

2. Debian

Debian (https://www.debian.org/) is an ancient open source binary distribution. It is both its own distribution and the benchmark for other well-known derivative versions, the most famous of which is Ubuntu (https://www.ubuntu.com/)).

Debian has a large number of pre-built software packages for ARM (IoT's preferred architecture), but given the advantages of Debian in the Intel ecosystem, these packages tend to support and maintain ARM binaries at a much lower level than their Intel counterparts. Therefore, metrics such as "more than 10000 built packages" do not make that much sense. You need to know the packages that are important to you and their support.

One disadvantage of many distributions used in self-managed settings, such as Debian, is that developers do not understand or remember that the installation of the package may not be completed on the computer where the package is eventually running, so they cannot rely on any functionality available to the target. Considering that this hassle is also a headache for the docker environment, and distributions put a lot of effort into cleaning up these dependencies, this is a smaller problem than ever before.

Setting up the build environment for a small number of packages is trivial, but building the infrastructure of all packages for the system can become important.

For these reasons, IoT's Debian is a good choice, in which case you only need to add or create some software packages to complete your platform.

3. EdgeX Foundry

Strictly speaking, EdgeX Foundry is not exactly a distribution because it has no problem with the BSP components of the distribution. BSP is the part that contains the Linux kernel itself, device drivers, and libraries for enabling hardware platforms. It starts at a higher level and requires a runnable Linux system based on docker support. From there, it provides a variety of containers that provide rich middleware and vertical sets for IoT devices, especially edge devices. (in docker's view, the container is a separate module that usually provides vertical functions, such as databases or network services that are almost independent of host operating systems, libraries, and so on).

The concept behind EdgeX Foundry points the way forward for large IoT devices, especially edge devices, but it remains to be done to define a more constrained version to provide a good set of benchmark services. Some progress has been made in this regard, and some services have been migrated from JVM to golang-based implementations, but in the near future, the coverage of IoT based on low-end and mid-range Linux is still out of reach.

3. Foundries.io Microplatform

Foundries.io uses a Yocto-based approach to create a Linux platform to create a board support layer and then layer a set of containerized microservices on top of it. Compared with the EdgeX Foundry method, their container set is smaller, more moderate, and has a visible smaller footprint.

Although Foundries.io products can be fully accessed and automatically updated and managed through subscriptions, the underlying platform is open source and available.

These are all the contents of the article "what are the Linux distributions of the Internet of things?" Thank you for reading! I believe you will gain a lot after reading this article. The editor will update different knowledge for you every day. If you want to learn more knowledge, please pay attention to the industry information channel.

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