Re: why is linux-libre-headers behind linux-libre?

[Pjotr Prins]

On Mon, Nov 06, 2017 at 03:44:41AM -0500, Mark H Weaver wrote:
> Are you sure about this?  My impression was that binaries compiled with
> newer linux-libre-headers can be run on older kernels.  If you were
> correct, then the binaries we've been building throughout 2017 could be
> reliably run only on linux-libre-4.4 or newer.
> 
> In fact, we've been successfully running these Guix binaries on
> hydra.gnu.org with its old 2.6.x kernel, and on build slaves running
> kernels older than 4.4.  Furthermore, I strongly suspect that many of
> our users (e.g. Trisquel users) have been running Guix on older kernels
> as well, and yet I don't recall seeing any bug reports related to this.
> 
> My recommendation would be to update linux-libre-headers to the latest
> LTS kernel (currently 4.9.x) in every core-updates cycle.
> 
> What do you think?

The Linux kernel API is remarkably stable. It is indeed the reason we
*can* run GNU Guix on older kernels in the first place - the kernel is
our single dependency. The headers do change, but mostly due to kernel
internals which are not used from glibc etc.

I remember for Nix there was a breaking kernel API change at
some point.  But it is extremely rare. Must have been 10 years ago.

Pj.
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