From mboxrd@z Thu Jan 1 00:00:00 1970 Path: main.gmane.org!not-for-mail From: Richard Stallman Newsgroups: gmane.emacs.devel Subject: Re: `exec shield' test in configure too strict? Date: Thu, 07 Oct 2004 12:44:30 -0400 Sender: emacs-devel-bounces+ged-emacs-devel=m.gmane.org@gnu.org Message-ID: References: <20041004212031.GB2219@fencepost> <01c4ab96$Blat.v2.2.2$19340460@zahav.net.il> Reply-To: rms@gnu.org NNTP-Posting-Host: deer.gmane.org X-Trace: sea.gmane.org 1097167511 16096 80.91.229.6 (7 Oct 2004 16:45:11 GMT) X-Complaints-To: usenet@sea.gmane.org NNTP-Posting-Date: Thu, 7 Oct 2004 16:45:11 +0000 (UTC) Cc: miles@gnu.org, jan.h.d@swipnet.se, emacs-devel@gnu.org Original-X-From: emacs-devel-bounces+ged-emacs-devel=m.gmane.org@gnu.org Thu Oct 07 18:44:59 2004 Return-path: Original-Received: from lists.gnu.org ([199.232.76.165]) by deer.gmane.org with esmtp (Exim 3.35 #1 (Debian)) id 1CFbNy-0003fG-00 for ; Thu, 07 Oct 2004 18:44:59 +0200 Original-Received: from localhost ([127.0.0.1] helo=lists.gnu.org) by lists.gnu.org with esmtp (Exim 4.33) id 1CFbUi-0001ea-Ry for ged-emacs-devel@m.gmane.org; Thu, 07 Oct 2004 12:51:56 -0400 Original-Received: from mailman by lists.gnu.org with tmda-scanned (Exim 4.33) id 1CFbUT-0001bl-Hv for emacs-devel@gnu.org; Thu, 07 Oct 2004 12:51:41 -0400 Original-Received: from exim by lists.gnu.org with spam-scanned (Exim 4.33) id 1CFbUS-0001bL-4r for emacs-devel@gnu.org; Thu, 07 Oct 2004 12:51:40 -0400 Original-Received: from [199.232.76.173] (helo=monty-python.gnu.org) by lists.gnu.org with esmtp (Exim 4.33) id 1CFbUR-0001bG-RA for emacs-devel@gnu.org; Thu, 07 Oct 2004 12:51:39 -0400 Original-Received: from [199.232.76.164] (helo=fencepost.gnu.org) by monty-python.gnu.org with esmtp (Exim 4.34) id 1CFbNY-0002Dt-Nd for emacs-devel@gnu.org; Thu, 07 Oct 2004 12:44:32 -0400 Original-Received: from rms by fencepost.gnu.org with local (Exim 4.34) id 1CFbNW-0004jx-SN; Thu, 07 Oct 2004 12:44:31 -0400 Original-To: Eli Zaretskii In-reply-to: <01c4ab96$Blat.v2.2.2$19340460@zahav.net.il> (eliz@gnu.org) X-BeenThere: emacs-devel@gnu.org X-Mailman-Version: 2.1.5 Precedence: list List-Id: "Emacs development discussions." List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Errors-To: emacs-devel-bounces+ged-emacs-devel=m.gmane.org@gnu.org Xref: main.gmane.org gmane.emacs.devel:28038 X-Report-Spam: http://spam.gmane.org/gmane.emacs.devel:28038 Doesn't this harm cross-building Emacs? I always thought that running a test program at configure time should be avoided, and that tests that only compile or link programs should be peferred. Yes, that is true. But maybe there is no way to test this based on the compilation environment. When cross compiling the test obviously can not be run, so configure assumes that the heap start address is not random. Come to think of it, the old test (checking /proc/sys/kernel/exec-shield) was worse, as it did not handle cross compiling. That will be right most of the time today, but that may not be true in the future. Can we modify unexec to handle this case correctly? What exactly is it that we now do in the case where we see that exec shield is enabled? How does that avoid the problem?