KOReader is available for multiple platforms. Here are instructions to build installable packages for all these platforms.
These instructions are intended for a Linux OS. MacOS and Windows users are suggested to develop in a Linux VM.
## Prerequisites
This instructions asume that you [have a development environment ready to run](Building.md) KOReader. If not then please install common prerequisites first.
### A toolchain for your target.
Each target has its own architecture and you'll need to setup a proper cross-compile toolchain. Your GCC should be at least version 4.9.
#### for Android
A compatible version of the Android NDK and SDK will be downloaded automatically by `./kodev release android` if no NDK or SDK is provided in environment variables. For that purpose you can use:
If you want to use your own installed tools please make sure that you have the **NDKr15c** and the SDK for Android 9 (**API level 28**) already installed.
#### for embedded linux devices
Cross compile toolchains are available for Ubuntu users through these commands:
**NOTE:** While, for some targets (specifically, Cervantes, Kindle & Kobo), we make *some* effort to support Linaro/Ubuntu TCs,
they do *not* exactly target the proper devices. While your build *may* go fine, this will *probably* lead to runtime failure.
As time goes by, and/or the more bleeding-edge your distro is, the greater the risk for mismatch gets.
Which means, that, unless you are *very* sure you know what you're doing, you'll want to use the exact same TCs we do, ones that target their respective platforms properly.
We have a distribution-agnostic solution to make that mostly painless: [koxtoolchain](https://github.com/koreader/koxtoolchain)!
This will allow you to build the *exact* same TCs used to build the nightlies, thanks to the magic of [crosstool-ng](https://github.com/crosstool-ng/crosstool-ng). These are also included precompiled in the Docker images for the respective targets.
