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

[Ludovic Courtès]

Mark H Weaver <address@hidden> skribis:

> 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.

You’re right, but my guess was that if the Omnipath library requires
specific kernel headers, then it may be using functionality (and
syscalls) only implemented by newer kernels.  I haven’t checked though.

Ludo’.