From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (qmail 17808 invoked by alias); 18 Jul 2015 18:18:52 -0000 Mailing-List: contact cygwin-apps-help@cygwin.com; run by ezmlm Precedence: bulk Sender: cygwin-apps-owner@cygwin.com List-Id: List-Subscribe: List-Archive: List-Post: List-Help: , Mail-Followup-To: cygwin-apps@cygwin.com Received: (qmail 16618 invoked by uid 89); 18 Jul 2015 18:18:51 -0000 Authentication-Results: sourceware.org; auth=none X-Virus-Found: No X-Spam-SWARE-Status: No, score=-2.0 required=5.0 tests=AWL,BAYES_00,KAM_LAZY_DOMAIN_SECURITY,RP_MATCHES_RCVD,SPF_HELO_PASS autolearn=ham version=3.3.2 X-HELO: mx1.redhat.com Received: from mx1.redhat.com (HELO mx1.redhat.com) (209.132.183.28) by sourceware.org (qpsmtpd/0.93/v0.84-503-g423c35a) with (AES256-GCM-SHA384 encrypted) ESMTPS; Sat, 18 Jul 2015 18:18:50 +0000 Received: from int-mx14.intmail.prod.int.phx2.redhat.com (int-mx14.intmail.prod.int.phx2.redhat.com [10.5.11.27]) by mx1.redhat.com (Postfix) with ESMTPS id E27A1CA648 for ; Sat, 18 Jul 2015 18:18:48 +0000 (UTC) Received: from [10.3.113.107] (ovpn-113-107.phx2.redhat.com [10.3.113.107]) by int-mx14.intmail.prod.int.phx2.redhat.com (8.14.4/8.14.4) with ESMTP id t6IIImaI008729 for ; Sat, 18 Jul 2015 14:18:48 -0400 Subject: Re: [ANNOUNCEMENT] Updated for 32-bit, new for 64-bit: libsigsegv-2.10-2 To: cygwin-apps@cygwin.com References: From: Eric Blake Openpgp: url=http://people.redhat.com/eblake/eblake.gpg X-Enigmail-Draft-Status: N1110 Message-ID: <55AA9882.1030407@redhat.com> Date: Sat, 18 Jul 2015 18:18:00 -0000 User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:38.0) Gecko/20100101 Thunderbird/38.0.1 MIME-Version: 1.0 In-Reply-To: Content-Type: multipart/signed; micalg=pgp-sha256; protocol="application/pgp-signature"; boundary="5nB3FQBpR4GGpSCcO4JDNVreNi4W03PWJ" X-IsSubscribed: yes X-SW-Source: 2015-07/txt/msg00097.txt.bz2 This is an OpenPGP/MIME signed message (RFC 4880 and 3156) --5nB3FQBpR4GGpSCcO4JDNVreNi4W03PWJ Content-Type: text/plain; charset=utf-8 Content-Transfer-Encoding: quoted-printable Content-length: 2022 On 07/17/2015 05:22 PM, Eric Blake (cygwin) wrote: > A new release of libsigsegv, 2.10-2, will soon be available for download > from your favorite mirror. On 32-bit cygwin, this leaves 2.10-1 as > previous; on 64-bit cygwin, it is a new port of the package, made > possible for the first time by new sigaltstack() code in cygwin 2.1.0. Oddly enough, this new library actually causes a regression in 32-bit m4 - with libsigsegv-2.10-1, I get stack overflow handling, but with -2, attempting to register the handler fails and m4 ends up dumping core on stack overflow. But it's not quite libsigsegv's fault. m4 was originally creating an alternate stack of 16k in size, based on a pure guess that it would be large enough (since the headers didn't declare any constant otherwise); but cygwin's sigaltstack() requires an alternate stack of 64k or larger. I see a couple of options: 1. see if we can relax cygwin.dll to live with a 16k alternate stack 2. recompile every application that linked against libsigsegv to make use of cygwin's new constants (at least those applications like m4 that were using shared gnulib code to guess at the right stack size will now guess correctly, hand a larger stack to libsigsegv, and libsigsegv can then just use sigaltstack() as desired) 3. recompile libsigsegv for 32-bit to put in a hack: if the stack size passed by the caller is < 64k but >=3D 16k, then fall back to the older back-door Windows native stack overflow handling. Option 1 is risky and might not be possible; option 2 will happen eventually, but option 3 seems like the smoothest way to avoid breaking things while waiting to reach the point of option 2. Of course, if we can get all maintainers to rebuild, then option 3 is wasted effort. How many applications would need to be rebuilt? I see: diffutils [me] m4 [me] clisp [Ken Brown] and nothing else mentioning libsigsegv in 32-bit setup.hints. --=20 Eric Blake eblake redhat com +1-919-301-3266 Libvirt virtualization library http://libvirt.org --5nB3FQBpR4GGpSCcO4JDNVreNi4W03PWJ Content-Type: application/pgp-signature; name="signature.asc" Content-Description: OpenPGP digital signature Content-Disposition: attachment; filename="signature.asc" Content-length: 604 -----BEGIN PGP SIGNATURE----- Version: GnuPG v2 Comment: Public key at http://people.redhat.com/eblake/eblake.gpg Comment: Using GnuPG with Thunderbird - http://www.enigmail.net/ iQEcBAEBCAAGBQJVqpiCAAoJEKeha0olJ0NqGCAIAJ4Yqs8N2Ivryn8wUVM1YfZu eTVoT79c1gpTkUy5Pbx67mhxQgHrj0MdTn2ZMKcYnfKoV1nk9FVPK6Rhx3SPGdXs lCuUJI4VNRzoho1owR4ZNQOOhGpEnvHv7ELZIBpO8Y0kHz5hDL95CyrfbKSUJdrd Vg3zhb9JwNm/0+uMlqkVVcKPkZRHwH66B9NHEu+Ipwd4ZrZljG0R3nkl4w3QUBw3 5eOlYoXqGRcR1RMbb+5oDLm9H7jczReGeOUtFnWQwawI3jRyqpcOpl7cWlKNWt7v tM/x5RHLvKbEHvv3nD7Ja+f/Z6rkSRNi9rZXKqtIGnJ6hbO9igIzAckQSqA3s68= =3QE3 -----END PGP SIGNATURE----- --5nB3FQBpR4GGpSCcO4JDNVreNi4W03PWJ--