On Sun, May 13, 2018 at 9:48 PM, Henri Sivonen <hsivo...@hsivonen.fi> wrote: > On Sun, May 13, 2018 at 9:34 PM, Matthias Klose <d...@ubuntu.com> wrote: >> On 13.05.2018 05:00, Henri Sivonen wrote: >>> On Thu, May 10, 2018 at 11:25 PM, Thomas Ward <tew...@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.)
As a datapoint, Fedora is pursuing compiling 32-bit x86 packages with SSE2 unconditionally enabled (including SSE floating-point math): https://fedoraproject.org/wiki/Changes/Update_i686_architectural_baseline_to_include_SSE2 -- Henri Sivonen hsivo...@hsivonen.fi https://hsivonen.fi/ -- Ubuntu-devel-discuss mailing list Ubuntu-devel-discuss@lists.ubuntu.com Modify settings or unsubscribe at: https://lists.ubuntu.com/mailman/listinfo/ubuntu-devel-discuss