[OFFTOPIC] Re: Represent NTP's origin time

[Stefan Monnier <monnier@iro.umontreal.ca>]

>> The support for 64bit time_t on 32bit platforms is quite old by now
>> actually, but it hasn't seen as much uptake as initially envisioned for
>> whatever reasons.  So in effect those platforms have announced their EOL
>> and you should move off them.

IIUC the issue is that the ripple effects of the change are non-trivial:
lots and lots of APIs include a time_t somewhere (where recompilation
leads to an incompatible ABI).  So changing time_t ends up requiring
recompiling (or, from the users's PoV upgrading) lots and lots of
packages, plus a lot of work to figure out which packages need
recompiling and which don't.  So the alternative of making a completely
new port is not much worse (implies more recompilation, admittedly, but
completely avoids the need to figure out which packages need
recompilation).

[ IIUC for i386 the plan for Debian is indeed to hope that the port will
  die before the 32bit limit becomes really unbearable.  Not sure what
  will happen with the ports for smaller systems where the move from
  32bit to 64bit is much younger (e.g. armhf).  ]

>> > The *BSDs and Linux (beyond kernel 5.6ish) do support 64 bit time_t
>> > in their 32 bit variants: perhaps this is an orientation.
>> I have no 32bit system left that can run a modern enough Linux kernel
>> and doesn't also support 64bit, so once I update those will not be 32bit
>> anymore.

FWIW, I use an amd64 kernel with a i386 Debian install on most of my machines.

> (I'd bet that Stefan's hardware is still 32 bit :)

I do still own several machines with a 32bit-only CPU:
- two armhf SBCs (both using the Allwinner A20 CPU) which I use as
  always-on servers.
- my old Thinkpad X30, which I use as "PDF to VGA adapter" when I teach.
- an old Thinkpad X60 which was supposed to replace the X30 but which I end up
  not using because the X30 still works well enough.
- my DSL modem/router (running a `mips` port of OpenWRT; a rare big-endian machine ;-)
- my smartphone
- my tablet

Admittedly, I don't use Debian on the last 3.

I also own 3 more machines which had a 32bit-only CPU (Core Duo)
originally but in which I retrofitted Core 2 Duos.

I tried using an amd64 Debian install on those machines that are limited
to 3GB of RAM and found that the increased memory pressure was
sufficiently noticeable that I decided to stick to i386.

> So basically it reduces to whether the Emacs project wants to
> support 32 bit systems (currently, the answer seems to be "yes")

Quite.

> and what to do about time_t when yes.

I don't think there's any need for Emacs to make any special effort in
this respect.


        Stefan