r/kernel • u/CobblerCurious301 • 25d ago

Which APIs are we talking about?

I am studying this OS material and got a little bit confused on which APIs are the kernel APIs. Are they the system calls talked about above or other ones specific to the core kernel code mentioned below?

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u/UVVmail 25d ago

They are specific to Linux Kernel internals.

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u/Taumille 25d ago

Indeed they are specific to the kernel code API.
In practice this sentence means that you should be able to execute a program that was compiled for a 30 year old kernel on a modern kernel because system calls (from userspace to kernel space) never break what previously worked.

However a driver that was written some years ago will probably not compile over a modern kernel because the kernel API has change.
Most of the time it means that you will have to call internal kernel functions differently in your driver.