From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (qmail 21074 invoked by alias); 16 Jan 2015 18:55:00 -0000 Mailing-List: contact gcc-bugs-help@gcc.gnu.org; run by ezmlm Precedence: bulk List-Id: List-Archive: List-Post: List-Help: Sender: gcc-bugs-owner@gcc.gnu.org Received: (qmail 21046 invoked by uid 48); 16 Jan 2015 18:54:53 -0000 From: "rearnsha at gcc dot gnu.org" To: gcc-bugs@gcc.gnu.org Subject: [Bug libstdc++/63829] _Lock_policy used in thread.cc can cause incompatibilities with binaries using different -mcpu Date: Fri, 16 Jan 2015 18:55:00 -0000 X-Bugzilla-Reason: CC X-Bugzilla-Type: changed X-Bugzilla-Watch-Reason: None X-Bugzilla-Product: gcc X-Bugzilla-Component: libstdc++ X-Bugzilla-Version: 4.9.2 X-Bugzilla-Keywords: X-Bugzilla-Severity: normal X-Bugzilla-Who: rearnsha at gcc dot gnu.org X-Bugzilla-Status: NEW X-Bugzilla-Priority: P3 X-Bugzilla-Assigned-To: unassigned at gcc dot gnu.org X-Bugzilla-Target-Milestone: --- X-Bugzilla-Flags: X-Bugzilla-Changed-Fields: Message-ID: In-Reply-To: References: Content-Type: text/plain; charset="UTF-8" Content-Transfer-Encoding: 7bit X-Bugzilla-URL: http://gcc.gnu.org/bugzilla/ Auto-Submitted: auto-generated MIME-Version: 1.0 X-SW-Source: 2015-01/txt/msg01580.txt.bz2 https://gcc.gnu.org/bugzilla/show_bug.cgi?id=63829 --- Comment #6 from Richard Earnshaw --- arm linux code should always be using the _S_atomic sequences. When the processor doesn't have the required instructions, kernel helper routines will be used. This ensures that code is forwards compatible to later architectures. It's a really bad idea for the headers used in user code to be changing this decision dynamically.