Re: Can we drop upstream Linux x32 support?

Thomas Schöbel-Theuer
2018-12-14T21:22:45Z

On 12/11/18 02:23, Andy Lutomirski wrote:
> I'm seriously considering sending a patch to remove x32 support from
> upstream Linux.

I am downstream maintainer of several self-patched kernels at 1&1 Ionos.
The kernels are rolled out to several tenthousands of production servers
running in several datacenters and in multiple continents.

Currently, we have a few thousands of servers relying on 32bit ABIs in
some thousands of VMs and/or containers of various types (LXC, OpenVZ, etc).

Here is my private opinion, not speaking for 1&1: at some point the
future, 32bit userspace support needs to be dropped anyway, somewhen in
future. This is inevitable in the very long term.

Thus the discussion should be about _timing_ / _roadmaps_, but not about
the fact as such.

My suggestion:

1) please release / declare a new LTS kernel, with upstream support for
at least 5 years (as usual). Currently, only 4.4 and 4.9 are marked as
LTS. Either mark another existing stable kernel as LTS, or a future one.

2) please _announce_ _now_ that after the _next_ LTS kernel (whichever
you want to declare as such), you will _afterwards_ drop the legacy
32bit support for 64 kernels (I am deliberately using "management speak"
here).

=> result: the industry should have to fair chance to deal with such a
roadmap. Yes, it will hurt some people, but they will have enough time
for their migration projects.

Example: I know that out of several millions of customers of webhosting,
a very low number of them have some very old legacy 32bit software
installed in their webspace. This cannot be supported forever. But the
number of such cases is very small, and there just needs to be enough
time for finding a solution for those few customers.

3) the next development kernel _after_ that LTS release can then
immediately drop the 32bit support. Enterprise users should have enough
time for planning, and for lots of internal projects modernizing their
infrastructure. Usually, they will need to do this anyway in the long term.

A roadmap should be _reliable_ for planning, and there should be no
"unexpected surprises". That's the most important requirements.

Notice: 5 years is what I know will very likely work for 1&1 Ionos. I
cannot speak for other large-scale enterprise users, but I think most of
them should be able to deal with suchalike intervals in a clear roadmap.

Addendum / side note: I know of cases where _critical_ / sometimes even
proprietary 32bit enterprise software needs to run for several
_decades_. Please don't drop KVM/qemu support for 32bit guests using
_old_ (unchanged) 32bit kernels, which are just happen to run on 64bit
hypervisors. But AFAICS that was not the intention of this initiative.
Just keep the latter in mind as another (independent) requirement.

Cheers,

Thomas