Re: [X86] Fwd: F29 System Wide Change: i686 Is For x86-64

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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.

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.)

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.

        Kevin Kofler
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