From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from pippin.tausq.org (gandalf.tausq.org [64.81.244.94]) by dsl2.external.hp.com (Postfix) with ESMTP id 169E54829 for ; Fri, 10 Jan 2003 00:50:15 -0700 (MST) Date: Thu, 9 Jan 2003 23:54:41 -0800 From: Randolph Chung To: John David Anglin Cc: parisc-linux@parisc-linux.org Message-ID: <20030110075441.GD31470@tausq.org> Reply-To: Randolph Chung References: <20021211224404.GC15219@systemhalted> <200212112305.gBBN5Bdj021432@hiauly1.hia.nrc.ca> Mime-Version: 1.0 Content-Type: text/plain; charset=us-ascii In-Reply-To: <200212112305.gBBN5Bdj021432@hiauly1.hia.nrc.ca> Subject: [parisc-linux] Re: floating point exception error Sender: parisc-linux-admin@lists.parisc-linux.org Errors-To: parisc-linux-admin@lists.parisc-linux.org List-Help: List-Post: List-Subscribe: , List-Id: parisc-linux developers list List-Unsubscribe: , List-Archive: In reference to a message from John David Anglin, dated Dec 11: > > The code _seems_ to trap on a PA8600. Though I won't say anything until > > I enable debugging in the trap handler and rerun the test. > > The code doesn't seem to trap on a A500 which I believe is a PA8500. > I think we need to look at bits 0..1 of the coprocessor configuration > register to determine instruction validity. See table 8-6 on page 8-11. > I can look at what the HP compiler does. Up to now, we have assumed > that all PA8000 machines have the same instruction set. i looked at this some more.. it's not that the fcnv instruction is not implemented by the processor, but we seem to be falling into one of the overflow/underflow cases... if you adjust the value being converted (say remove one of the zeros), the program works without trapping. page 10-9 of the pa20 arch manual gives the conditions under which a floating point conversion op will cause an unimplemented exception. however my reading of the text is that an exception is only generated if the overflow/underflow exceptions are enabled. i've tried explicitly calling feclearexcept(FE_ALL_EXCEPT) before doing the fp op but it still causes the unimplemented exception trap. The kernel debugs seem to indicate the O/U exceptions are not set as well.... puzzled, randolph -- Randolph Chung Debian GNU/Linux Developer, hppa/ia64 ports http://www.tausq.org/