Are there any internal kernel ABI/API guarantees in -stable releases?

Are there any internal kernel ABI/API guarantees in -stable releases?

[Chris Friesen]

Hi everyone,

Looking at 
https://www.kernel.org/doc/html/latest/process/stable-kernel-rules.html 
there are a number of criteria for patches to -stable releases.

However, there is no mention of preserving the stability of internal 
kernel ABIs and/or APIs.

Do successive patch releases of -stable kernels provide any guarantees 
that they will not change ABIs and/or APIs, remove functionality, change 
behaviour, etc.?   For example, would a -stable commit be allowed to 
make a change that would break an out-of-tree (but open-source) device 
driver if that's the only way to fix a bug?

I know that during the development of new major/minor versions 
developers are free to break ABIs and APIs at will as long as they fix 
up all the in-tree code.  Does that still hold true for -stable commits 
or do things get more restrictive?

Thanks,
Chris

Re: Are there any internal kernel ABI/API guarantees in -stable releases?

[Greg KH]

On Thu, May 29, 2025 at 01:48:26PM -0600, Chris Friesen wrote:
> Hi everyone,
> 
> Looking at
> https://www.kernel.org/doc/html/latest/process/stable-kernel-rules.html
> there are a number of criteria for patches to -stable releases.
> 
> However, there is no mention of preserving the stability of internal kernel
> ABIs and/or APIs.

That is because there is no such guarantee.

Hope this helps,

greg k-h