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kotlinlang

Is there a way to compile without OS support (not via zephyr)

Not out of the box, but generally Zephyr port is a good start for such activity

Let me give some background, basically I want to write an operating system for say the RPiv3, so with some assembly and then a small chunk of C I should be able to climb into kotlin/native

So are you suggesting I look at how the zephyr port is implemented and then write my own?

yes, pretty much, also Kotlin/Native can compile to the static library, so this mode may be helpful for you

Native seems pretty reliant on a runtime. Im assuming there is a "simple" interface to implement to provide the runtime calls that native needs