From owner-freebsd-hackers@FreeBSD.ORG Sat Sep 28 11:25:55 2013 Return-Path: Delivered-To: freebsd-hackers@freebsd.org Received: from mx1.freebsd.org (mx1.freebsd.org [8.8.178.115]) (using TLSv1 with cipher ADH-AES256-SHA (256/256 bits)) (No client certificate requested) by hub.freebsd.org (Postfix) with ESMTP id 39B4F850 for ; Sat, 28 Sep 2013 11:25:55 +0000 (UTC) (envelope-from dim@FreeBSD.org) Received: from tensor.andric.com (tensor.andric.com [IPv6:2001:7b8:3a7:1:2d0:b7ff:fea0:8c26]) (using TLSv1 with cipher ADH-CAMELLIA256-SHA (256/256 bits)) (No client certificate requested) by mx1.freebsd.org (Postfix) with ESMTPS id EF2C32625 for ; Sat, 28 Sep 2013 11:25:54 +0000 (UTC) Received: from [IPv6:2001:7b8:3a7::c1de:2ac5:7b4a:4aa5] (unknown [IPv6:2001:7b8:3a7:0:c1de:2ac5:7b4a:4aa5]) (using TLSv1 with cipher AES128-SHA (128/128 bits)) (No client certificate requested) by tensor.andric.com (Postfix) with ESMTPSA id 7BB375C44; Sat, 28 Sep 2013 13:25:49 +0200 (CEST) Content-Type: multipart/signed; boundary="Apple-Mail=_3EF7EB08-9956-427A-A572-2DD3BAD153E3"; protocol="application/pgp-signature"; micalg=pgp-sha1 Mime-Version: 1.0 (Mac OS X Mail 6.6 \(1510\)) Subject: Re: Mixing amd64 kernel with i386 world From: Dimitry Andric In-Reply-To: <20130928103758.GC27231@server.rulingia.com> Date: Sat, 28 Sep 2013 13:25:39 +0200 Message-Id: <30CAFBF9-4119-4E3D-A5B0-4520E35F1601@FreeBSD.org> References: <20130928103758.GC27231@server.rulingia.com> To: Peter Jeremy X-Mailer: Apple Mail (2.1510) Cc: freebsd-hackers@freebsd.org X-BeenThere: freebsd-hackers@freebsd.org X-Mailman-Version: 2.1.14 Precedence: list List-Id: Technical Discussions relating to FreeBSD List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , X-List-Received-Date: Sat, 28 Sep 2013 11:25:55 -0000 --Apple-Mail=_3EF7EB08-9956-427A-A572-2DD3BAD153E3 Content-Transfer-Encoding: 7bit Content-Type: text/plain; charset=us-ascii On Sep 28, 2013, at 12:37, Peter Jeremy wrote: > I have a system with 4GB RAM and hence need to use an amd64 kernel to use > all the RAM (I can only access 3GB RAM with an i386 kernel). OTOH, amd64 > processes are significantly (50-100%) larger than equivalent i386 processes > and none none of the applications I'll be running on the system need to be > 64-bit. > > This implies that the optimal approach is an amd64 kernel with i386 > userland (I'm ignoring PAE as a useable approach). I've successfully > run i386 jails on amd64 systems so I know this mostly works. I also > know that there are some gotchas: > - kdump needs to match the kernel > - anything accessing /dev/mem or /dev/kmem (which implies anything that > uses libkvm) probably needs to match the kernel. > > Has anyone investigated this approach? I have only run i386 jails on amd64, just like you. Though for the use case you are describing, the really optimal approach would be to have real x32 support. Unfortunately, that is quite a lot of work... :) -Dimitry --Apple-Mail=_3EF7EB08-9956-427A-A572-2DD3BAD153E3 Content-Transfer-Encoding: 7bit Content-Disposition: attachment; filename=signature.asc Content-Type: application/pgp-signature; name=signature.asc Content-Description: Message signed with OpenPGP using GPGMail -----BEGIN PGP SIGNATURE----- Version: GnuPG/MacGPG2 v2.0.20 (Darwin) iEYEARECAAYFAlJGvLgACgkQsF6jCi4glqPkOQCfc5USkKfbfI38xL9oNLMpy+cN ko0AoLh/IZpYCL2Y85NmLfKihFORz2bM =gXK/ -----END PGP SIGNATURE----- --Apple-Mail=_3EF7EB08-9956-427A-A572-2DD3BAD153E3--