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

[Mark H Weaver]

Hi,

address@hidden (Ludovic Courtès) writes:

> Dave Love <address@hidden> skribis:
>
>> Efraim Flashner <address@hidden> writes:
>>
>>> On Tue, Oct 31, 2017 at 02:00:35PM +0100, Vincent Legoll wrote:
>>>> Hello,
>>>> 
>>>> On Tue, Oct 31, 2017 at 1:35 PM, Dave Love <address@hidden> wrote:
>>>> > Why is linux-libre-headers a long way behind linux-libre (currently at
>>>> > version 4.4.47, compared with 4.13.10 for linux-libre)?
>>>> 
>>>> I suspect this is due to massive rebuilding that would occur when
>>>> updating linux-libre-headers
>
> That and also because glibc targets (can target) older kernels, which is
> something we rely on.
>
>>> This is typically updated in the core-updates branch, but it hasn't been
>>> updated yet. Based on the LTS versions, we should upgrade it to the 4.9
>>> branch.
>>
>> Thanks for the explanations.  I checked that 4.9 would support the
>> Omnipath library, at least.
>
> The Omnipath library relies on Linux (not libc) headers, and a specific
> version thereof?
>
> I suppose we could also introduce a more recent version of
> ‘linux-libre-headers’ specifically for this purpose, with the
> understanding that the resulting binaries rely on a specific kernel
> version.

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?

      Mark