Re: expected baseline changes for forky => proposal no more FPU and 80bits float/double on i386

On Sat, Aug 15, 2026 at 02:22:24PM +0200, Stephen Kitt wrote:
> Hi,

Hi Stephen,

> On Sat, 15 Aug 2026 13:20:20 +0300, Adrian Bunk <[email protected]> wrote:
> > On Fri, Aug 14, 2026 at 09:23:58PM +0900, Simon Richter wrote:
> > > The floating point results change, though, so the behaviour is different
> > > from what the software was tested with, especially the rounding behaviour
> > > is a lot more aggressive.
> > >...  
> > 
> > you can compile software relying on the old behaviour with -mfpmath=387.
> 
> The typical use-case here though is that you have an existing i386 binary,
> which you can’t recompile, running with distribution-provided i386 libraries
> (or a mixture of i386 libraries provided alongside the binary and
> distribution-provided libraries), and it’s the behaviour of the libraries
> that may have changed.

this whole line of arguing comes across as asking to continue to do a 
lot of work with a mostly theoretical argument.

glibc already uses SSE when available, and there aren't that many other 
relevant libraries without any ABI break in decades.

If there are a handful relevant libraries, continuing to use x87 for 
these would be easily possible.

Does anyone have an example of actual breakage?

> Regards,
> 
> Stephen

cu
Adrian