Date: Mon, 2 Dec 1996 11:13:52 +0100 (MEZ) From: "Hr.Ladavac" <lada@ws2301.gud.siemens.co.at> To: phk@critter.tfs.com (Poul-Henning Kamp) Cc: peter@spinner.dialix.com, freebsd-smp@freebsd.org Subject: Re: Pentium CPU steppings Message-ID: <199612021013.AA243241632@ws2301.gud.siemens.co.at> In-Reply-To: <3057.849292563@critter.tfs.com> from "Poul-Henning Kamp" at Nov 29, 96 07:36:03 pm
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E-mail message from Poul-Henning Kamp contained: > > In message <199611291828.CAA19491@spinner.DIALix.COM>, Peter Wemm writes: > >Poul-Henning Kamp wrote: > >> >Hmm, I wonder if it's safe to test for this at the end of npx.c in the > >> >kernel? > >> > >> Linux can do it, so why couldn't we ? > > > >Yeah, but have you ever seen it report "yes"? Last I checked, (2.0.twenty > >something), the code looked very much like it hardwired the "fdiv bug > >present?" result to "no" and I could not find any code in the kernel that > > yes, they circumvent it, I belive in their compiler :-) But do they circumvent it in all instances? According to c't magazine, Intel admitted that some other operations that internally use FDIV are also buggy. From the top of my head: ATAN ATAN2 and about 5 or 6 others. N.B. the interpolation trick does not help at all if you use these (and practically all of ray-tracing software does ): /Marino > > -- > Poul-Henning Kamp | phk@FreeBSD.ORG FreeBSD Core-team. > http://www.freebsd.org/~phk | phk@login.dknet.dk Private mailbox. > whois: [PHK] | phk@ref.tfs.com TRW Financial Systems, Inc. > Future will arrive by its own means, progress not so. >
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