From mboxrd@z Thu Jan 1 00:00:00 1970 Path: news.gmane.org!not-for-mail From: Colin Baxter Newsgroups: gmane.emacs.devel Subject: Re: USE_LSB_TAG not supported on this platform Date: Wed, 10 Feb 2016 19:29:58 +0000 Message-ID: <87io1wz7m1.fsf@yandex.com> References: <86powcjei0.wl-herbert@mailbox.org> <56B3F962.8010203@cs.ucla.edu> <86mvrejegc.wl-herbert@mailbox.org> <86si15ygd9.wl-herbert@mailbox.org> <85twlksgds.fsf@iznogoud.viz> <8660y0nqze.wl-herbert@mailbox.org> <56B8F03C.3010709@cs.ucla.edu> <83lh6vot83.fsf@gnu.org> <56B9A5B1.5080101@cs.ucla.edu> <83bn7pddlu.fsf@gnu.org> <56BA23CB.4070001@cs.ucla.edu> <83r3glbw3c.fsf@gnu.org> NNTP-Posting-Host: plane.gmane.org Mime-Version: 1.0 Content-Type: text/plain X-Trace: ger.gmane.org 1455132625 24892 80.91.229.3 (10 Feb 2016 19:30:25 GMT) X-Complaints-To: usenet@ger.gmane.org NNTP-Posting-Date: Wed, 10 Feb 2016 19:30:25 +0000 (UTC) To: emacs-devel@gnu.org Original-X-From: emacs-devel-bounces+ged-emacs-devel=m.gmane.org@gnu.org Wed Feb 10 20:30:17 2016 Return-path: Envelope-to: ged-emacs-devel@m.gmane.org Original-Received: from lists.gnu.org ([208.118.235.17]) by plane.gmane.org with esmtp (Exim 4.69) (envelope-from ) id 1aTaSv-0001Ga-Dk for ged-emacs-devel@m.gmane.org; Wed, 10 Feb 2016 20:30:17 +0100 Original-Received: from localhost ([::1]:42368 helo=lists.gnu.org) by lists.gnu.org with esmtp (Exim 4.71) (envelope-from ) id 1aTaSu-0005NQ-Rx for ged-emacs-devel@m.gmane.org; Wed, 10 Feb 2016 14:30:16 -0500 Original-Received: from eggs.gnu.org ([2001:4830:134:3::10]:51997) by lists.gnu.org with esmtp (Exim 4.71) (envelope-from ) id 1aTaSr-0005NB-9l for emacs-devel@gnu.org; Wed, 10 Feb 2016 14:30:14 -0500 Original-Received: from Debian-exim by eggs.gnu.org with spam-scanned (Exim 4.71) (envelope-from ) id 1aTaSn-0000tW-Ub for emacs-devel@gnu.org; Wed, 10 Feb 2016 14:30:13 -0500 Original-Received: from plane.gmane.org ([80.91.229.3]:40871) by eggs.gnu.org with esmtp (Exim 4.71) (envelope-from ) id 1aTaSn-0000tQ-Nu for emacs-devel@gnu.org; Wed, 10 Feb 2016 14:30:09 -0500 Original-Received: from list by plane.gmane.org with local (Exim 4.69) (envelope-from ) id 1aTaSm-00019n-Dg for emacs-devel@gnu.org; Wed, 10 Feb 2016 20:30:08 +0100 Original-Received: from host86-133-197-254.range86-133.btcentralplus.com ([86.133.197.254]) by main.gmane.org with esmtp (Gmexim 0.1 (Debian)) id 1AlnuQ-0007hv-00 for ; Wed, 10 Feb 2016 20:30:08 +0100 Original-Received: from m43cap by host86-133-197-254.range86-133.btcentralplus.com with local (Gmexim 0.1 (Debian)) id 1AlnuQ-0007hv-00 for ; Wed, 10 Feb 2016 20:30:08 +0100 X-Injected-Via-Gmane: http://gmane.org/ Original-Lines: 43 Original-X-Complaints-To: usenet@ger.gmane.org X-Gmane-NNTP-Posting-Host: host86-133-197-254.range86-133.btcentralplus.com User-Agent: Gnus/5.13 (Gnus v5.13) Emacs/25.1.50 (gnu/linux) Cancel-Lock: sha1:gFyQw9sk3+cVcAo2BSOIZ/OMMEs= X-detected-operating-system: by eggs.gnu.org: Genre and OS details not recognized. X-Received-From: 80.91.229.3 X-BeenThere: emacs-devel@gnu.org X-Mailman-Version: 2.1.14 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 Original-Sender: emacs-devel-bounces+ged-emacs-devel=m.gmane.org@gnu.org Xref: news.gmane.org gmane.emacs.devel:199720 Archived-At: >> Cc: herbert@mailbox.org, emacs-devel@gnu.org, m43cap@yandex.com >> From: Paul Eggert >> Date: Tue, 9 Feb 2016 09:37:15 -0800 >> >> On 02/09/2016 08:59 AM, Eli Zaretskii wrote: >> > Thanks. Out of curiosity: which hosts can behave like that? >> >> 16-bit PDP-11s running 7th Edition Unix. malloc returned only a multiple >> of 2 there. :-) > > There's only one 16-bit platform supported by Emacs: MS-DOS. And > there the problem doesn't exist, because the library switches the CPU > to 32-bit mode. > >> > Also, why are we sure that the loops will end at some point on those >> > hosts? Shouldn't we perhaps set a limit to the loop iterations, to be >> > sure we don't infloop there? >> >> We're not absolutely sure. Certainly the C standard doesn't guarantee >> it; malloc can return a pointer that is always odd, on weird platforms >> where alignof always returns 1. I view this as almost purely theoretical >> though, due to the practical performance benefit of alignment to at >> least sizeof(double). It's conceivable (though very unlikely) that Emacs >> will infloop on some truly oddball platform that does not care about >> performance; but if that happens it'll be OK, as the infloop would >> almost surely happen during a build and the builder would then send us a >> bug report and we can deal with it then. I think adding a counter would >> complicate the code (and possibly introduce bugs, in code that's never >> really exercised) for not enough benefit. > > Maybe these considerations are worth having as comments near the loop, > so that whoever bumps into the problem will know faster and better > what to do. > > Thanks. You might like to know that the latest git-pull builds satisfactorily for me, giving Emacs 25.1.50.1 (i686-pc-linux-gnu, GTK+ Version 3.4.2) of 2016-02-10 Best wishes, Colin.