Re: Question: Is there a plan when to require a higher Linux kernel version than 3.2?

[Joseph Myers <joseph@codesourcery.com>]

On Thu, 22 Sep 2022, Michael Hudson-Doyle via Libc-alpha wrote:

> On Thu, 22 Sept 2022 at 04:50, Joseph Myers <joseph@codesourcery.com> wrote:
> 
> > * The oldest kernel version supported on
> > https://www.kernel.org/category/releases.html (currently 4.9) being new
> > enough for the change to allow significant cleanups in glibc.
> >
> 
> I don't know how seriously you are suggesting moving the baseline to 4.9 or
> on what timeframe, but we (Canonical) still have Ubuntu 14.04 (kernel 3.13)
> in extended support until 2024 and 16.04 (kernel 4.4) until 2026 and we
> would like these users to be able to use newer distributions in containers

I think that container hosts running much newer distributions in 
containers must be expected to update the host kernel, or backport some 
new syscalls, rather than expecting new distributions to have libc working 
on a ten-year-old kernel.  (New distributions probably do want to have 
libc that works on the kernel used by any prior version of that 
distribution from which in-place upgrades are supported, but that 
shouldn't require support for ten-year-old kernels.)

To benefit significantly (in terms of source code cleanup) from updating 
the minimum kernel in glibc, I think the new minimum would need to be at 
least 4.4; older versions wouldn't allow removing lots of socketcall code, 
so I don't think an update would be worthwhile until we're ready to move 
to 4.4 or later as the new minimum.

(Technically there's also the option of having an older minimum version on 
x86_64, which we did for a while before, since x86_64 doesn't use 
socketcall anyway so much of the benefit could be gained by updating the 
minimum on other architectures.)

-- 
Joseph S. Myers
joseph@codesourcery.com