From mboxrd@z Thu Jan 1 00:00:00 1970 Path: news.gmane.org!.POSTED!not-for-mail From: Barry Warsaw Newsgroups: gmane.emacs.devel Subject: Emacs 25.1 build failures on Ubuntu arm64 Date: Tue, 28 Mar 2017 20:30:40 -0400 Organization: Damn Crazy Followers of the Horn Message-ID: <20170328203040.0a1e0b98@subdivisions.wooz.org> NNTP-Posting-Host: blaine.gmane.org Mime-Version: 1.0 Content-Type: multipart/signed; micalg=pgp-sha256; boundary="Sig_/JnSQiwgrdkQbq9nEpV9b42g"; protocol="application/pgp-signature" X-Trace: blaine.gmane.org 1490747515 4215 195.159.176.226 (29 Mar 2017 00:31:55 GMT) X-Complaints-To: usenet@blaine.gmane.org NNTP-Posting-Date: Wed, 29 Mar 2017 00:31:55 +0000 (UTC) To: emacs-devel@gnu.org Original-X-From: emacs-devel-bounces+ged-emacs-devel=m.gmane.org@gnu.org Wed Mar 29 02:31:51 2017 Return-path: Envelope-to: ged-emacs-devel@m.gmane.org Original-Received: from lists.gnu.org ([208.118.235.17]) by blaine.gmane.org with esmtp (Exim 4.84_2) (envelope-from ) id 1ct1We-0000N5-Vk for ged-emacs-devel@m.gmane.org; Wed, 29 Mar 2017 02:31:49 +0200 Original-Received: from localhost ([::1]:55796 helo=lists.gnu.org) by lists.gnu.org with esmtp (Exim 4.71) (envelope-from ) id 1ct1Wk-0004Ri-PX for ged-emacs-devel@m.gmane.org; Tue, 28 Mar 2017 20:31:54 -0400 Original-Received: from eggs.gnu.org ([2001:4830:134:3::10]:58651) by lists.gnu.org with esmtp (Exim 4.71) (envelope-from ) id 1ct1Vx-0004QJ-Ra for emacs-devel@gnu.org; Tue, 28 Mar 2017 20:31:07 -0400 Original-Received: from Debian-exim by eggs.gnu.org with spam-scanned (Exim 4.71) (envelope-from ) id 1ct1Vt-0004bq-Tg for emacs-devel@gnu.org; Tue, 28 Mar 2017 20:31:05 -0400 Original-Received: from [195.159.176.226] (port=49659 helo=blaine.gmane.org) by eggs.gnu.org with esmtps (TLS1.0:RSA_AES_128_CBC_SHA1:16) (Exim 4.71) (envelope-from ) id 1ct1Vt-0004aa-Fs for emacs-devel@gnu.org; Tue, 28 Mar 2017 20:31:01 -0400 Original-Received: from list by blaine.gmane.org with local (Exim 4.84_2) (envelope-from ) id 1ct1Vg-0003WH-ED for emacs-devel@gnu.org; Wed, 29 Mar 2017 02:30:48 +0200 X-Injected-Via-Gmane: http://gmane.org/ Original-Lines: 81 Original-X-Complaints-To: usenet@blaine.gmane.org X-Newsreader: Claws Mail 3.14.1 (GTK+ 2.24.31; x86_64-pc-linux-gnu) X-detected-operating-system: by eggs.gnu.org: GNU/Linux 2.2.x-3.x [generic] [fuzzy] X-Received-From: 195.159.176.226 X-BeenThere: emacs-devel@gnu.org X-Mailman-Version: 2.1.21 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" Xref: news.gmane.org gmane.emacs.devel:213471 Archived-At: --Sig_/JnSQiwgrdkQbq9nEpV9b42g Content-Type: text/plain; charset=US-ASCII Content-Transfer-Encoding: quoted-printable I'm not sure how much of this email will be actionable, but I wanted to at least let y'all know about a problem we've seen building Emacs 25.1 on Ubun= tu 17.04 arm64. Quick background: In Ubuntu we have a few minor changes above the package in Debian, which we mostly inherit. One of those changes is that we build with -j1 on arm64 only. There are a couple of other changes that shouldn't have= an impact on the problem I'll describe, but the changelogs can be easily inspected. In any case, for several weeks now we've seen Emacs segfault on arm64 build= ers consistently in what I think are the CEDET tests. The full traceback, when we've been able to capture it, is here: https://launchpadlibrarian.net/302409391/gdb-bt-full.txt The full build log is here: https://launchpadlibrarian.net/310046964/buildlog_ubuntu-zesty-arm64.emacs2= 5_25.1+1-3ubuntu3~ppa0_BUILDING.txt.gz (scroll to the bottom to see the crash) and the bug that tracks this is here: https://bugs.launchpad.net/ubuntu/+source/emacs25/+bug/1656474 We're using gcc based on 6.2.1/6.3.0 (depending on the build). All the other architectures have been building fine, but arm64 crashes consistently on our build machines. Attempts to reproduce the crash on development machines, even on arm64 chroots and bare metal have not been successful, so debugging the problem isn't easy. Based on some research in= to other crashes, various other attempts to work around the problem, and some discussions among Ubuntu developers on IRC, we wondered whether turning off optimization would help. Indeed, adding -O0 to CFLAGS only on arm64 solved the problem in a test build. I've now uploaded a new build to the archive with -O0 on arm64 and I expect this to build and get published once it's approved (Ubuntu is currently in final beta freeze). I'll watch this thread via Gmane and try to answer any additional questions you might have. As I said, I'm not sure what the Emacs developers can do about it, but I wanted you to know about the problem and how we think we've solved it. Cheers, -Barry --Sig_/JnSQiwgrdkQbq9nEpV9b42g Content-Type: application/pgp-signature Content-Description: OpenPGP digital signature -----BEGIN PGP SIGNATURE----- iQIcBAEBCAAGBQJY2wAwAAoJEBJutWOnSwa/lJgQAMNNa66H0odFh4BOY2cPuB5h Z49GdF6VSWJccADOJW05it/Qoxj/wpJnphuJHeUl2oxmJViLBwP5U1AawR2kcI7G oiqAM0imAQ4AQIz4DXF5R+eyK1jH1UWeAJlZaGGO3BlbsOcTTO2UzbvjE83sSLLn Ook5E+TeevgSLatR9uw0FAv0hFYhGQN5poioPBk5fPp2JIYB10dC6r2t3UQz3Upq McI6s1d6M1DTF1vhCoYxZ/PUJ6cwXbPm/9lJJLLqxc4sT1v3y4oF1+uILYMmUrI6 8bja2MzfZNCbHxeBjfcqq68r7dWtBYuXB+SunxOQ3HTOpridDt3TNR5j1UNEbGRm 2BdObVgZ7kusSVbjCyL7SA2EXqi2et+wJ1jZAm3wkS5amuiljm2m1kq+T6Ne9BTN jDzjOQPfkjMvZdSc4G3GQnf4MC2PReScsyqImbN2USprQCgHRuelgpin450W/Tvf sWy+GMThqen6lY6E4asNza9GPRVDstow15kWWHTUg5cguxlYFUW8ceX/tv3J85wt Lnv5UhUFArDvZhRImIm8AYJFi+MPQXC4VBR4libnq1/8c/lQVfe7uW3rsmltSeBY JuySy00S21Gtr66NYsvH4Gi3yL/RdpCUxaXbeyQuT7RQsIymUi3DWxyljXAyLPRJ zi94rBCNMvw+dwWmf4G4 =s6GX -----END PGP SIGNATURE----- --Sig_/JnSQiwgrdkQbq9nEpV9b42g--