From mboxrd@z Thu Jan 1 00:00:00 1970 Received: by oss.sgi.com id ; Thu, 23 Nov 2000 08:25:56 -0800 Received: from aux-209-217-49-36.oklahoma.net ([209.217.49.36]:13064 "EHLO proteus.paralogos.com") by oss.sgi.com with ESMTP id ; Thu, 23 Nov 2000 08:25:30 -0800 Received: from Ulysses ([195.154.177.178]) by proteus.paralogos.com (8.9.3/8.9.3) with SMTP id RAA06892; Thu, 23 Nov 2000 17:14:46 +0100 Message-ID: <009d01c0556a$74eda6c0$0deca8c0@Ulysses> From: "Kevin D. Kissell" To: "Dan Aizenstros" , References: <3A1D3DA1.E982879B@vcubed.com> Subject: Re: Strange messages. Date: Thu, 23 Nov 2000 17:28:06 +0100 MIME-Version: 1.0 Content-Type: text/plain; charset="iso-8859-1" Content-Transfer-Encoding: 7bit X-Priority: 3 X-MSMail-Priority: Normal X-Mailer: Microsoft Outlook Express 5.50.4133.2400 X-MimeOLE: Produced By Microsoft MimeOLE V5.50.4133.2400 Sender: owner-linux-mips@oss.sgi.com Precedence: bulk Return-Path: X-Orcpt: rfc822;linux-mips-outgoing This really deserves to be in the FAQ. I guess I ought to put a version of this up an a web site somewhere and just point people to the URL: Either Ralf or I end up answering it about once a month. This message occurs when the kernel gets an "unimplemented operation" trap from the FPU, which means that an FP instruction has been issued that the hardware cannot handle on its own. Usually this is a conversion of an extreme value or an operation on a denormalized value. What the OS is supposed to do in this case is to deal with the situation, by killing the process, fixing up the values, or emulating the instruction in software. Setting flush-denormal-to-zero mode of the FPU and replaying the instruction to see if that helps is a slightly shady (in my opinion) hack that Ralf put in as part of a tiny, minimal emulator that handled these exceptions in some versions of MIPS Linux. MIPS later integrated a full IEEE FPU emulator from Algorithmics into the 2.2.12 kernel, but it hasn't yet gone into the 2.3/2.4 repository. So long as all you got was that message, and awk didn't subsequently dump core, you're probably OK. Just don't do any serious numerical programming on the system until the full IEEE support goes in! Kevin K. ----- Original Message ----- From: "Dan Aizenstros" To: Sent: Thursday, November 23, 2000 4:54 PM Subject: Strange messages. > Hello All, > > Recently I upgraded my Linux/MIPS kernel from 2.2.12 to > 2.4.0-test9 and I started getting messages like the following: > > Setting flush to zero for awk. > > I did not get this message when using a 2.2.12 kernel but I am > getting them with a 2.4.0-test9 kernel. > > The 2.4.0-test9 kernel is based on the code from the snapshot > at oss.sgi.com in the following file, > /pub/linux/mips/mips-linux/simple/crossdev/src/linux-001027.tar.gz > with the patches from the same directory applied. > > I get the message many times and for different programs during > system startup. > > Has anyone seen this before? > > Dan Aizenstros > Software Engineer > V3 Semiconductor Corp. > From mboxrd@z Thu Jan 1 00:00:00 1970 Message-ID: <009d01c0556a$74eda6c0$0deca8c0@Ulysses> From: "Kevin D. Kissell" References: <3A1D3DA1.E982879B@vcubed.com> Subject: Re: Strange messages. Date: Thu, 23 Nov 2000 17:28:06 +0100 MIME-Version: 1.0 Content-Type: text/plain; charset="iso-8859-1" Content-Transfer-Encoding: 7bit Sender: owner-linux-mips@oss.sgi.com Return-Path: To: Dan Aizenstros , linux-mips@oss.sgi.com Message-ID: <20001123162806.NVlZaLFjYcbMtmxWTkhHlxLoHQHFYwzThtk3KcQ-DcA@z> This really deserves to be in the FAQ. I guess I ought to put a version of this up an a web site somewhere and just point people to the URL: Either Ralf or I end up answering it about once a month. This message occurs when the kernel gets an "unimplemented operation" trap from the FPU, which means that an FP instruction has been issued that the hardware cannot handle on its own. Usually this is a conversion of an extreme value or an operation on a denormalized value. What the OS is supposed to do in this case is to deal with the situation, by killing the process, fixing up the values, or emulating the instruction in software. Setting flush-denormal-to-zero mode of the FPU and replaying the instruction to see if that helps is a slightly shady (in my opinion) hack that Ralf put in as part of a tiny, minimal emulator that handled these exceptions in some versions of MIPS Linux. MIPS later integrated a full IEEE FPU emulator from Algorithmics into the 2.2.12 kernel, but it hasn't yet gone into the 2.3/2.4 repository. So long as all you got was that message, and awk didn't subsequently dump core, you're probably OK. Just don't do any serious numerical programming on the system until the full IEEE support goes in! Kevin K. ----- Original Message ----- From: "Dan Aizenstros" To: Sent: Thursday, November 23, 2000 4:54 PM Subject: Strange messages. > Hello All, > > Recently I upgraded my Linux/MIPS kernel from 2.2.12 to > 2.4.0-test9 and I started getting messages like the following: > > Setting flush to zero for awk. > > I did not get this message when using a 2.2.12 kernel but I am > getting them with a 2.4.0-test9 kernel. > > The 2.4.0-test9 kernel is based on the code from the snapshot > at oss.sgi.com in the following file, > /pub/linux/mips/mips-linux/simple/crossdev/src/linux-001027.tar.gz > with the patches from the same directory applied. > > I get the message many times and for different programs during > system startup. > > Has anyone seen this before? > > Dan Aizenstros > Software Engineer > V3 Semiconductor Corp. >