Messages in this thread | | | Subject | Re: [PATCH] MIPS: Provide Kconfig option for default IEEE754 conformance mode | From | Zhou Yanjie <> | Date | Thu, 6 Aug 2020 04:49:52 +0800 |
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在 2020/8/3 下午5:01, Jiaxun Yang 写道: > > > 在 2020/8/3 上午5:46, Maciej W. Rozycki 写道: >> On Fri, 31 Jul 2020, Serge Semin wrote: >> >>>> Requested by downstream distros, a Kconfig option for default >>>> IEEE754 conformance mode allows them to set their mode to >>>> relaxed by default. >>> That's what should have been here in the first place. Thanks! >> Well, originally plans were there to have NaN interlinking implemented >> and no such mess or desire for hacks like one here would result. Cf.: >> >> <https://gcc.gnu.org/ml/gcc/2015-11/msg00068.html>, >> <https://gcc.gnu.org/ml/gcc/2016-05/msg00137.html>, >> >> and then: >> >> <https://lkml.org/lkml/2015/11/16/386>, >> <https://sourceware.org/ml/libc-alpha/2015-11/msg00485.html>, >> <https://sourceware.org/ml/binutils/2015-11/msg00170.html>, >> <https://gcc.gnu.org/ml/gcc-patches/2015-11/msg03241.html>. >> >> You could well pick this work up and complete it if you like. Final >> conclusions for further work were made here: >> >> <https://gcc.gnu.org/ml/gcc/2016-11/msg00027.html>, >> <https://gcc.gnu.org/ml/gcc/2017-08/msg00260.html>, >> <https://gcc.gnu.org/ml/gcc/2017-10/msg00142.html>. >> >> In the relaxed mode math programs may produce wrong results unless you >> rebuild all your software for the correct NaN mode for the hardware used > > Unfortunately most of the hardware guys didn't understood the > difficulty here. > They decided to implement their hardware (P5600 & LS3A4000) as NaN2008 > only. >
All SoCs based on Ingenic XBurst2 CPU core are also NaN2008 only.
> I was thinking about let Kernel drop SIGFPE exception was caused by > mismatched NaN, > as most applications don't rely on signaling NaN, but it is still a > dirty hack. Not a good > idea in general. > > Thanks. > > - Jiaxun > >> (in which case you don't need the relaxed setting in the first place). > >> >> Maciej
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