Proposal: Let's drop i386

[Lyn Perrine]

The other question is does anyone test ubuntu on non SSE2 hardware anymore?

On Sun, May 13, 2018 at 11:48 AM, Henri Sivonen <hsivonen at hsivonen.fi>
wrote:

> On Sun, May 13, 2018 at 9:34 PM, Matthias Klose <doko at ubuntu.com> wrote:
> > On 13.05.2018 05:00, Henri Sivonen wrote:
> >> On Thu, May 10, 2018 at 11:25 PM, Thomas Ward <teward at thomas-ward.net>
> wrote:
> >>> However, killing i386 support globally could introduce issues,
> including
> >>> but not limited to certain upstream softwares having to go away
> >>> entirely, due to the interdependency or issues with how certain apps
> >>> work (read; Wine, 32-bit support, 64-bit support being flaky, and
> >>> Windows apps being general pains in that they work on 32bit but not
> >>> always on 64-bit).
> >>
> >> If 32-bit x86 support becomes mainly a thing that's run on x86_64
> >> hardware as a compatibility measure for things like Wine, it would
> >> make sense to bring the instruction set baseline to the x86_64 level.
> >> Specifically, it would make sense to compile the 32-bit x86 packages
> >> with SSE2 unconditionally enabled.
> >>
> >> This would mean dropping support for Pentium Pro and earlier or Athlon
> >> XP and earlier, but it's pretty sad to leave all that performance on
> >> the table in order to support the few computers still in use that have
> >> Pentium Pro or earlier or Athlon XP or earlier.
> >>
> >> As upstream software assumes SSE2 as the baseline, it will be less and
> >> less a run-time check and compiling software without SSE2 will mean
> >> shipping it in a damaged form performance-wise.
> >
> > I disagree, until you provide data how many packages fail to build, at
> least in
> > the testsuites, when run without the extra x87 precision bits.
>
> I don't have this data, but considering that SSE2 is a mandatory part
> of x86_64, it seems implausible that packages would be
> SSE2-intolerant. Considering that x86_64 defaults to SSE2
> floating-point math (or does Ubuntu override this?) and considering
> that ARM doesn't have x87 available, it seems implausible that
> packages would rely on x87. (On the contrary, since e.g. Firefox and
> Chromium upstreams don't do non-SSE2 x86 builds anymore, it seems more
> plausible that there exist packages whose upstream doesn't test x87
> floating-point math anymore.)
>
> --
> Henri Sivonen
> hsivonen at hsivonen.fi
> https://hsivonen.fi/
>
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