U boot list devices3/20/2023 ![]() ![]() ![]() The root-filesystem is loaded in to device memory and mounted as a tmpfs. When running a “Single Copy” update strategy you rely on a “Recovery OS”, which is normally a minimal Linux kernel and a minimal root-filesystem, just enough features to allow the device to boot and perform updates. You normally have an “hard-coded” area where you put your boot-loader and this is something that is decided by the SoC. The partitioning of your device could look like this when running a “Single Copy” strategy: You would probably deploy software updates using this method if you have a device with very limited storage space which does not allow you to run a “Dual Copy” strategy (more on this below). This is usually only a problem when you perform OTA updates using a mobile connection (GPRS, 3G, LTE etc.). The image size can typical be reduced using compression but it will still be of a significant size. There is one draw back with image based updates and that is actuall size of the update image, and this of course because we always do full OS upgrades. Which basically confirms what I just wrote, that ordinary package managers are not reliable enough to accomplish the above which is a critical requirement on embedded devices. Make your servers identical, and easily roll back if there’s an upgrade problem And if you are not able to mirror your release to all you devices you are in a testing/configuration hell.Įven Fedora, Redhat and CentOS have realized this, as they now provide an Atomic Host distribution which is hybrid of image based updates with rpm ( rpm-ostree).Ītomically update your system from the latest upstream OStree. Using package managers it is hard to “mirror” your release across thousands of devices, which is easily accomplished with image based updates. One power-loss in an update sequence and you have introduced “weirdness” in to your device from which you will never recover from. And this is one of the core requirements for a robust software update solution. Package managers do not perform atomic updates. ![]() And it can only go downhill from here :). Desktop package managers are not designed with embedded device uses-cases in mind. It works on desktop why can I not use this for my embedded device? Well you can, but I would not choose to go down this path voluntarily. It is quite common that this question arises. That is package managers (dpkg, rpm etc.). By reading this it will be easier to follow my coming articles because each project has chosen one or more strategies to focus on and I wanted to write down the pros and cons unrelated to any project. Updating Embedded Linux Devices: Backgroundīefore I start talking about different projects I wanted to write a bit about common update strategies on embedded Linux systems unrelated to any specific project.This post if part of the “Updating embedded Linux devices” series, previous posts are: ![]()
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