From owner-freebsd-amd64@FreeBSD.ORG Tue Feb 17 19:01:10 2009 Return-Path: Delivered-To: freebsd-amd64@freebsd.org Received: from mx1.freebsd.org (mx1.freebsd.org [IPv6:2001:4f8:fff6::34]) by hub.freebsd.org (Postfix) with ESMTP id 588241065673 for ; Tue, 17 Feb 2009 19:01:10 +0000 (UTC) (envelope-from peterjeremy@optushome.com.au) Received: from mail16.syd.optusnet.com.au (mail16.syd.optusnet.com.au [211.29.132.197]) by mx1.freebsd.org (Postfix) with ESMTP id C389B8FC37 for ; Tue, 17 Feb 2009 19:01:09 +0000 (UTC) (envelope-from peterjeremy@optushome.com.au) Received: from server.vk2pj.dyndns.org (c122-106-216-167.belrs3.nsw.optusnet.com.au [122.106.216.167]) by mail16.syd.optusnet.com.au (8.13.1/8.13.1) with ESMTP id n1HJ17qb022115 (version=TLSv1/SSLv3 cipher=DHE-RSA-AES256-SHA bits=256 verify=NO) for ; Wed, 18 Feb 2009 06:01:07 +1100 X-Bogosity: Ham, spamicity=0.000000 Received: from server.vk2pj.dyndns.org (localhost.vk2pj.dyndns.org [127.0.0.1]) by server.vk2pj.dyndns.org (8.14.3/8.14.3) with ESMTP id n1HJ16E7001788 for ; Wed, 18 Feb 2009 06:01:06 +1100 (EST) (envelope-from peter@server.vk2pj.dyndns.org) Received: (from peter@localhost) by server.vk2pj.dyndns.org (8.14.3/8.14.3/Submit) id n1HJ16Q6001787 for freebsd-amd64@freebsd.org; Wed, 18 Feb 2009 06:01:06 +1100 (EST) (envelope-from peter) Date: Wed, 18 Feb 2009 06:01:06 +1100 From: Peter Jeremy To: freebsd-amd64@freebsd.org Message-ID: <20090217190106.GB1351@server.vk2pj.dyndns.org> MIME-Version: 1.0 Content-Type: multipart/signed; micalg=pgp-sha1; protocol="application/pgp-signature"; boundary="82I3+IH0IqGh5yIs" Content-Disposition: inline X-PGP-Key: http://members.optusnet.com.au/peterjeremy/pubkey.asc User-Agent: Mutt/1.5.19 (2009-01-05) Subject: 32-bit truncation of 64-bit values X-BeenThere: freebsd-amd64@freebsd.org X-Mailman-Version: 2.1.5 Precedence: list List-Id: Porting FreeBSD to the AMD64 platform List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , X-List-Received-Date: Tue, 17 Feb 2009 19:01:11 -0000 --82I3+IH0IqGh5yIs Content-Type: text/plain; charset=us-ascii Content-Disposition: inline Content-Transfer-Encoding: quoted-printable Having just tracked down an issue caused by a pointer-to-int truncation, it occurs to me that it might be "instructive" to change the amd64 memory map so that the botton 4GB of address-space was unmapped by default (ie code, data, bss, stack and mmap all default to above 4GB). I notice that the process space layout has already changed since 7.x was branched (at least the same executable runs on 7.x and SEGVs on -current due to a truncated pointer) and making this change might reveal more broken code. Given how close we are to 8.0, this might need to wait until after 8 is branched. --=20 Peter Jeremy --82I3+IH0IqGh5yIs Content-Type: application/pgp-signature Content-Disposition: inline -----BEGIN PGP SIGNATURE----- Version: GnuPG v2.0.10 (FreeBSD) iEYEARECAAYFAkmbCXIACgkQ/opHv/APuIe0jQCeMbNbzkt0l6QwMl9srEkWm1Um vhcAoJgA9OEiRGWHgdHGEV4dzRKqAQSq =qwXM -----END PGP SIGNATURE----- --82I3+IH0IqGh5yIs--