Re: Can we drop upstream Linux x32 support?

Thomas Schoebel-Theuer
2018-12-15T07:42:14Z

On 12/14/18 22:41, Thomas Schöbel-Theuer wrote:
> On 12/14/18 22:24, Andy Lutomirski wrote:
>>
>> I'm talking about x32, which is a different beast.
>>
>
> So from my viewpoint the mentioned roadmap / timing requirements will
> remain the same, whatever you are dropping.
>
> Enterprise-critical use cases will probably need to be migrated to
> KVM/qemu together with their old kernel versions, anyway (because the
> original hardware will be no longer available in a few decades).
>

Here is a systematic approach to the problem.

AFAICS legacy 32bit userspace code (which exists in some notable masses)
can be executed at least in the following ways:

1) natively on 32bit-capable hardware, under 32bit kernels. Besides
legacy hardware, this also encompasses most current Intel / AMD 64bit
hardware in 32bit compatibility mode.

2) under 64bit kernels, using the 32bit compat layer from practically
any kernel version.

3) under KVM/qemu.

When you just drop 1), users have a fair chance by migrating to any of
the other two possibilities.

As explained, a time frame of ~5 years should work for the vast majority.

If you clearly explain the migration paths to your users (and to the
press), I think it will be acceptable.

[side note: I know of a single legacy instance which is now ~20 years
old, but makes a revenue of several millions per month. These guys have
large quantities of legacy hardware in stock. And they have enough money
to hire a downstream maintainer in case of emergency.]

Fatal problems would only arise if you would drop all three
possibilities in the very long term.

In ~100 years, possibility 3) should be sufficient for handling use
cases like preservation of historic documents. The latter is roughly
equivalent to running binary-only MSDOS, Windows NT, and similar, even
in 100 years, and even non-natively under future hardware architectures.