From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (qmail 20435 invoked by alias); 12 Jun 2012 19:11:37 -0000 Received: (qmail 20424 invoked by uid 22791); 12 Jun 2012 19:11:36 -0000 X-SWARE-Spam-Status: No, hits=-3.6 required=5.0 tests=AWL,BAYES_00,KHOP_RCVD_UNTRUST,RCVD_IN_HOSTKARMA_W,RCVD_IN_HOSTKARMA_WL X-Spam-Check-By: sourceware.org Received: from relay1.mentorg.com (HELO relay1.mentorg.com) (192.94.38.131) by sourceware.org (qpsmtpd/0.43rc1) with ESMTP; Tue, 12 Jun 2012 19:11:22 +0000 Received: from nat-ies.mentorg.com ([192.94.31.2] helo=EU1-MAIL.mgc.mentorg.com) by relay1.mentorg.com with esmtp id 1SeWUr-00072d-8R from joseph_myers@mentor.com ; Tue, 12 Jun 2012 12:11:21 -0700 Received: from digraph.polyomino.org.uk ([172.16.63.104]) by EU1-MAIL.mgc.mentorg.com with Microsoft SMTPSVC(6.0.3790.1830); Tue, 12 Jun 2012 20:11:19 +0100 Received: from jsm28 (helo=localhost) by digraph.polyomino.org.uk with local-esmtp (Exim 4.74) (envelope-from ) id 1SeWUo-000185-GN; Tue, 12 Jun 2012 19:11:18 +0000 Date: Tue, 12 Jun 2012 19:11:00 -0000 From: "Joseph S. Myers" To: libc-ports@sourceware.org, linux-arm-kernel@lists.infradead.org Subject: Detecting support for trapping floating-point exceptions on ARM Message-ID: MIME-Version: 1.0 Content-Type: TEXT/PLAIN; charset=US-ASCII Mailing-List: contact libc-ports-help@sourceware.org; run by ezmlm Precedence: bulk List-Id: List-Subscribe: List-Post: List-Help: , Sender: libc-ports-owner@sourceware.org X-SW-Source: 2012-06/txt/msg00021.txt.bz2 ARM VFPv3 and VFPv4 do not support trapping floating-point exceptions; VFPv2, VFPv3U and VFPv4U do. The lack of support causes the glibc math/test-fenv test to fail on VFPv3 and VFPv4 systems. The natural fix for that would be for fesetenv (FE_NOMASK_ENV) to fail on hardware not supporting trapping exceptions. There is, however, no HWCAP bit to indicate whether trapping floating-point exceptions is supported. Could one be added to the kernel, or is there a good way fesetenv could detect this from userspace without a new HWCAP bit? -- Joseph S. Myers joseph@codesourcery.com