From mboxrd@z Thu Jan 1 00:00:00 1970 Received: by oss.sgi.com id ; Wed, 24 Jan 2001 18:52:10 -0800 Received: from [12.44.186.158] ([12.44.186.158]:47861 "EHLO hermes.mvista.com") by oss.sgi.com with ESMTP id ; Wed, 24 Jan 2001 18:51:52 -0800 Received: from mvista.com (IDENT:ppopov@zeus.mvista.com [10.0.0.112]) by hermes.mvista.com (8.11.0/8.11.0) with ESMTP id f0P2mkI20510; Wed, 24 Jan 2001 18:48:46 -0800 Message-ID: <3A6F94E0.4AB07CEB@mvista.com> Date: Wed, 24 Jan 2001 18:52:16 -0800 From: Pete Popov Organization: Monta Vista Software X-Mailer: Mozilla 4.75 [en] (X11; U; Linux 2.2.17 i586) X-Accept-Language: bg, en MIME-Version: 1.0 To: carlson@sibyte.com CC: "linux-mips@oss.sgi.com" Subject: Re: floating point on Nevada cpu References: <3A6F8F66.6258801@mvista.com> <0101241833281Q.00834@plugh.sibyte.com> Content-Type: text/plain; charset=us-ascii Content-Transfer-Encoding: 7bit Sender: owner-linux-mips@oss.sgi.com Precedence: bulk Return-Path: X-Orcpt: rfc822;linux-mips-outgoing Justin Carlson wrote: > > On Wed, 24 Jan 2001, Pete Popov wrote: > > This simple test fails on a Nevada (5231) cpu: > > > > int main() > > { > > float x1,x2,x3; > > > > x1 = 7.5; > > x2 = 2.0; > > x3 = x1/x2; > > printf("x3 = %f\n", x3); > > } > > > > Ummm...care to tell *how* it fails? Here it is: sh-2.03# ./fl x3 = 0.000000 I'm running a test9 based kernel, but the same kernel compiled for my Indigo2 produces the right result. Also, the uptime commands complains with: Unknown HZ value! (2147483647) Assume 100. At the console, I get "Setting flush to zero for uptime." So, I took a look at arch/mips/kernel/traps.c and the kernel retries the instruction with denormalized instructions flushed to zero. However, the 5200 signals an unimplemented operation even if the FS bit is set. In any case, the first simple test doesn't run into the "flush to zero" problem but the result is still bad. Pete