From owner-freebsd-current@FreeBSD.ORG Thu Apr 2 08:48:40 2009 Return-Path: Delivered-To: current@freebsd.org Received: from mx1.freebsd.org (mx1.freebsd.org [IPv6:2001:4f8:fff6::34]) by hub.freebsd.org (Postfix) with ESMTP id 67E3F1065674 for ; Thu, 2 Apr 2009 08:48:40 +0000 (UTC) (envelope-from kostikbel@gmail.com) Received: from mail.terabit.net.ua (mail.terabit.net.ua [195.137.202.147]) by mx1.freebsd.org (Postfix) with ESMTP id 0B9C58FC19 for ; Thu, 2 Apr 2009 08:48:39 +0000 (UTC) (envelope-from kostikbel@gmail.com) Received: from skuns.zoral.com.ua ([91.193.166.194] helo=mail.zoral.com.ua) by mail.terabit.net.ua with esmtps (TLSv1:AES256-SHA:256) (Exim 4.63 (FreeBSD)) (envelope-from ) id 1LpIbF-000Pnj-Il; Thu, 02 Apr 2009 11:48:37 +0300 Received: from deviant.kiev.zoral.com.ua (root@deviant.kiev.zoral.com.ua [10.1.1.148]) by mail.zoral.com.ua (8.14.2/8.14.2) with ESMTP id n328mYVf011170 (version=TLSv1/SSLv3 cipher=DHE-RSA-AES256-SHA bits=256 verify=NO); Thu, 2 Apr 2009 11:48:34 +0300 (EEST) (envelope-from kostikbel@gmail.com) Received: from deviant.kiev.zoral.com.ua (kostik@localhost [127.0.0.1]) by deviant.kiev.zoral.com.ua (8.14.3/8.14.3) with ESMTP id n328mYSF090830; Thu, 2 Apr 2009 11:48:34 +0300 (EEST) (envelope-from kostikbel@gmail.com) Received: (from kostik@localhost) by deviant.kiev.zoral.com.ua (8.14.3/8.14.3/Submit) id n328mX8V090829; Thu, 2 Apr 2009 11:48:33 +0300 (EEST) (envelope-from kostikbel@gmail.com) X-Authentication-Warning: deviant.kiev.zoral.com.ua: kostik set sender to kostikbel@gmail.com using -f Date: Thu, 2 Apr 2009 11:48:33 +0300 From: Kostik Belousov To: Luigi Rizzo Message-ID: <20090402084833.GZ31897@deviant.kiev.zoral.com.ua> References: <20090402070605.GA96848@onelab2.iet.unipi.it> Mime-Version: 1.0 Content-Type: multipart/signed; micalg=pgp-sha1; protocol="application/pgp-signature"; boundary="GNE9ETaGyP7vJxQo" Content-Disposition: inline In-Reply-To: <20090402070605.GA96848@onelab2.iet.unipi.it> User-Agent: Mutt/1.4.2.3i X-Virus-Scanned: ClamAV version 0.94.2, clamav-milter version 0.94.2 on skuns.kiev.zoral.com.ua X-Virus-Status: Clean X-Spam-Status: No, score=-4.4 required=5.0 tests=ALL_TRUSTED,AWL,BAYES_00 autolearn=ham version=3.2.5 X-Spam-Checker-Version: SpamAssassin 3.2.5 (2008-06-10) on skuns.kiev.zoral.com.ua X-Virus-Scanned: mail.terabit.net.ua 1LpIbF-000Pnj-Il be94835d1d34e6e67bf4fc89afa2d219 X-Terabit: YES Cc: current@freebsd.org Subject: Re: cmpxchg / atomic_cmpset_int emulation for userland (i386) ? X-BeenThere: freebsd-current@freebsd.org X-Mailman-Version: 2.1.5 Precedence: list List-Id: Discussions about the use of FreeBSD-current List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , X-List-Received-Date: Thu, 02 Apr 2009 08:48:41 -0000 --GNE9ETaGyP7vJxQo Content-Type: text/plain; charset=us-ascii Content-Disposition: inline Content-Transfer-Encoding: quoted-printable On Thu, Apr 02, 2009 at 09:06:05AM +0200, Luigi Rizzo wrote: > Hi, > I have some list manipulation algorithm that I would like to use > that relies rather centrally on atomic_cmpset_int(). >=20 > This is an atomic instruction on 486+, but not available on 386 > and maybe other platforms. i386/atomic.h has a replacement > but it uses "pushfl; cli; ... popfl;" so it cannot run in userland. >=20 > I was wondering if there is a good emulation for that instruction > on the i386 that is suitable for userland (other architectures > we support have a CPU instruction that does it, or in the case of ARM, > a usable emulation for userland). FreeBSD cannot boot on anything < 486, i.e. cmpxchgl and xaddl may be considered always supported by the CPU. --GNE9ETaGyP7vJxQo Content-Type: application/pgp-signature Content-Disposition: inline -----BEGIN PGP SIGNATURE----- Version: GnuPG v1.4.9 (FreeBSD) iEYEARECAAYFAknUe+AACgkQC3+MBN1Mb4gWZwCgzqRxTpUB03rwi1Az4/wvB09p A/8AoO10q/FZ/xdf+gWajB8FqkAVMdHC =bhYi -----END PGP SIGNATURE----- --GNE9ETaGyP7vJxQo--