X-Recipient: archive-cygwin AT delorie DOT com DomainKey-Signature: a=rsa-sha1; c=nofws; d=sourceware.org; h=list-id :list-unsubscribe:list-subscribe:list-archive:list-post :list-help:sender:subject:to:references:from:message-id:date :mime-version:in-reply-to:content-type :content-transfer-encoding; q=dns; s=default; b=sxCNsGvPPFCaCVFW fi/Q9WeYyk/NdROCtp3lB1VQmga+Crzb+OiKMiQe+7EzbhJI063X6VHNG8GW+aTC T+2931yUx/1WjfPRiTpcIiN9zEtbadvL6e2NCYZf1/rpE5f8iHnu65YkZXdgtGjn OCA2f1TOksaLH7K+qhMTboC9GoE= DKIM-Signature: v=1; a=rsa-sha1; c=relaxed; d=sourceware.org; h=list-id :list-unsubscribe:list-subscribe:list-archive:list-post :list-help:sender:subject:to:references:from:message-id:date :mime-version:in-reply-to:content-type :content-transfer-encoding; s=default; bh=D0DLnJHNqlxJfUBwOQPDbt CpvWY=; b=iQlKfBoJ3o8DumgUgcudfqmEqEt85wUUJHZDgVM3LkX6OJE0xH/DBN 3FG7TOuSGPZNJjcbKEaOPJC0rjUgycqNwP+/2bfe1Ujx3CZmrgc5M2lvcyk2Z9UC GyegkNfO5bL+kl6uE9CaQRxWR/C2VYKoRmvkG+vApqjQ9Y0F/HpeY= Mailing-List: contact cygwin-help AT cygwin DOT com; run by ezmlm List-Id: List-Subscribe: List-Archive: List-Post: List-Help: , Sender: cygwin-owner AT cygwin DOT com Mail-Followup-To: cygwin AT cygwin DOT com Delivered-To: mailing list cygwin AT cygwin DOT com Authentication-Results: sourceware.org; auth=none X-Virus-Found: No X-Spam-SWARE-Status: No, score=-2.3 required=5.0 tests=AWL,BAYES_00,FREEMAIL_FROM,RCVD_IN_DNSWL_LOW,SPF_PASS autolearn=ham version=3.3.2 spammy=jon, Turney, turney, Jon X-HELO: mail-qg0-f50.google.com X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20130820; h=x-gm-message-state:subject:to:references:from:message-id:date :user-agent:mime-version:in-reply-to:content-transfer-encoding; bh=7/7WndDotZQe4p4fm7o3BJlL2KR4zqTonnlTNLzongs=; b=OLsU5jI55SkDIkjiTj5CMlIN47+sKnKTV9rKbM2Ejbz0uDG/uDHGrGVqIGLxvJCCXN MUT26fsAUWAPOrQfycOcah27wXjQXf6aA5FBlz0xBYi5mKOZ4JWRxMT+TNzhjhYx23iz 7eyryeIWyjz+9dR6Qj2T7cmLV71gxO0JDB5OSSYkPKaJRxoNSvdpUHLDPJRWFZTeD11f ZGsKqX/Fpp2y8VvKLlzlMAgWoODOycvBooFf7d19dRz/93SQY1JzPQ8qjkf058lV9ZAQ HktgjRcMPQ1rYo7cNODaZ1We+vDk41cAX5l7fcgNnwcudMrJOiq1XVsdQhIvjMaItWuy bl9Q== X-Gm-Message-State: AD7BkJJyuU7fB9rVe4O6bHQq/12qRVctvOnpPqMOq9tADy9vS5MwWlSPAS6jVBRUEVQqjg== X-Received: by 10.140.156.138 with SMTP id c132mr49040892qhc.96.1458646223685; Tue, 22 Mar 2016 04:30:23 -0700 (PDT) Subject: Re: X widget question To: cygwin AT cygwin DOT com References: <56EE7412 DOT 8080708 AT gmail DOT com> <56F11C12 DOT 80900 AT dronecode DOT org DOT uk> From: Marco Atzeri Message-ID: <56F12CC4.4000502@gmail.com> Date: Tue, 22 Mar 2016 12:30:12 +0100 User-Agent: Mozilla/5.0 (Windows NT 6.1; WOW64; rv:38.0) Gecko/20100101 Thunderbird/38.7.0 MIME-Version: 1.0 In-Reply-To: <56F11C12.80900@dronecode.org.uk> Content-Type: text/plain; charset=utf-8; format=flowed Content-Transfer-Encoding: 7bit X-IsSubscribed: yes On 22/03/2016 11:18, Jon Turney wrote: > On 20/03/2016 09:57, Marco Atzeri wrote: >> I have finally identified where ncview was >> segfaulting on X86_64 >> >> The solution was to reverse the order of destruction >> for a chain of widgets > > Nice to see that you have resolved this. > > It's not clear from what you write if you are sure there is an > undocumented ordering constraint (which just happens to not crash on > 32-bit), or if reversing the ordering just happens to make things not > crash on 64-bit I suspect the second: Reversing the order just don't trigger the crash as no reformatting of the constraint chain is needed. As ncview view works on other 64 bit platform, it seems a cygwin specific issue. Debugging the issue I always noted mismatch of 16 bytes in related pointers. But as I know little of libXt internals I could misunderstand it. >> The segfault was inside Xlib when managing the constraints. >> >> As the segfault did not happened on i686, is it possible >> that is a race inside Xlib ? >> I have not found in the X Documentation nothing about >> requested order of widget destruction in this case. > > Possible, yes. It seems more likely that there is a documentation > error, or a bug in handling widgets which share a constraint being > destroyed out of order. > > I'm afraid finding someone who cares greatly about libXt will be hard, > but do you think it would now be possible to craft a test case which > demonstrates the problem? I was considering it, as ncview is likely not the only program with this potential problem. Time to learn a bit of X programming... Regards Marco -- Problem reports: http://cygwin.com/problems.html FAQ: http://cygwin.com/faq/ Documentation: http://cygwin.com/docs.html Unsubscribe info: http://cygwin.com/ml/#unsubscribe-simple