Thanks for the response and sorry for taking so long to reply.
On Mon, Jun 18, 2018 at 10:05 PM, Kevin Kofler <kevin.kofler@xxxxxxxxx> wrote:
Jeff Backus wrote:
> Hmm.. Yes, we've had discussions within the SIG re: window managers that
> support i586/i686, and KDE was on the list of WMs that no longer support
> our target system. Do these patches/hacks only apply to KDE or do they
> apply to Qt in general?
The absolute worst is QtWebEngine. Chromium dropped support for non-SSE2 x86
years ago, so I had to cumulatively revert a whole bunch of commits that
removed runtime SSE2 detection where it was present and added some more
unconditional SSE2 optimizations. And now V8 (the _javascript_ engine that
Chromium relies on) dropped the x87 backend (i.e., the one using x87 rather
than SSE2 for floating-point operations, hence working on non-SSE2 x86
machines) for their JIT entirely (and there is no interpreter-only
fallback), so I am even stuck trying to port the x87 backend to each new Qt
branch (which uses a newer Chromium and thus a newer V8). This is a huge
effort, and nobody outside of Fedora cares about non-SSE2 anymore. Even
distros that claim to support non-SSE2 hardware just ship QtWebEngine as
SSE2 only. I haven't seen any other distro even picking up my patch, let
alone working on it. The Fedora Chromium, V8 and Node.js packagers also do
not care.
Wow. Yes, that is a heavy lift. Thank you for your efforts! :) It helps to see how expensive non-SSE2 support is. Thanks.
I think Google sucks for desupporting hardware that way, but I also do not
think maintaining the V8 x87 backend on our own is going to scale in the
long run. My time is limited and I do not currently see anybody else among
the Fedora Qt maintainers who is at the same time both able and willing to
maintain it. (This needs somebody with plenty of free time and with some
experience working on compilers.)
Agreed. Is the only reason to maintain the x87 backend for non-SSE2 support?
So the QtWebEngine no-sse2 patch is definitely going to be dropped from
F29+, given the FESCo decision on this issue. For F27 and F28, I will look
into it and see what I can do.
Thank you.
Cheers,
Jeff
_______________________________________________ devel mailing list -- devel@xxxxxxxxxxxxxxxxxxxxxxx To unsubscribe send an email to devel-leave@xxxxxxxxxxxxxxxxxxxxxxx Fedora Code of Conduct: https://getfedora.org/code-of-conduct.html List Guidelines: https://fedoraproject.org/wiki/Mailing_list_guidelines List Archives: https://lists.fedoraproject.org/archives/list/devel@xxxxxxxxxxxxxxxxxxxxxxx/message/XGXDROC66RS5DGUGQV5NONBJR2TRMRQQ/
