From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (qmail 12316 invoked by alias); 15 Feb 2011 17:56:47 -0000 Received: (qmail 12221 invoked by uid 22791); 15 Feb 2011 17:56:46 -0000 X-SWARE-Spam-Status: No, hits=-5.6 required=5.0 tests=AWL,BAYES_00,RCVD_IN_DNSWL_HI,SPF_HELO_PASS,T_RP_MATCHES_RCVD X-Spam-Check-By: sourceware.org Received: from mx1.redhat.com (HELO mx1.redhat.com) (209.132.183.28) by sourceware.org (qpsmtpd/0.43rc1) with ESMTP; Tue, 15 Feb 2011 17:56:44 +0000 Received: from int-mx01.intmail.prod.int.phx2.redhat.com (int-mx01.intmail.prod.int.phx2.redhat.com [10.5.11.11]) by mx1.redhat.com (8.14.4/8.14.4) with ESMTP id p1FHuPLJ030148 (version=TLSv1/SSLv3 cipher=DHE-RSA-AES256-SHA bits=256 verify=OK); Tue, 15 Feb 2011 12:56:25 -0500 Received: from freie.oliva.athome.lsd.ic.unicamp.br (ovpn01.gateway.prod.ext.phx2.redhat.com [10.5.9.1]) by int-mx01.intmail.prod.int.phx2.redhat.com (8.13.8/8.13.8) with ESMTP id p1FHuJHf002850 (version=TLSv1/SSLv3 cipher=DHE-RSA-AES256-SHA bits=256 verify=NO); Tue, 15 Feb 2011 12:56:25 -0500 Received: from livre.localdomain (livre-to-gw.oliva.athome.lsd.ic.unicamp.br [172.31.160.19]) by freie.oliva.athome.lsd.ic.unicamp.br (8.14.4/8.14.4) with ESMTP id p1FHuGaI022833; Tue, 15 Feb 2011 15:56:16 -0200 Received: from livre.localdomain (aoliva@localhost.localdomain [127.0.0.1]) by livre.localdomain (8.14.3/8.14.3/Debian-5+lenny1) with ESMTP id p1FHuC2x026366; Tue, 15 Feb 2011 15:56:12 -0200 Received: (from aoliva@localhost) by livre.localdomain (8.14.3/8.14.3/Submit) id p1FHu5pE026360; Tue, 15 Feb 2011 15:56:06 -0200 From: Alexandre Oliva To: David Daney Cc: linux-mips , GCC , binutils , Prasun Kapoor Subject: Re: RFC: A new MIPS64 ABI References: <4D5990A4.2050308@caviumnetworks.com> Date: Tue, 15 Feb 2011 17:56:00 -0000 In-Reply-To: <4D5990A4.2050308@caviumnetworks.com> (David Daney's message of "Mon, 14 Feb 2011 12:29:24 -0800") Message-ID: User-Agent: Gnus/5.13 (Gnus v5.13) Emacs/23.1 (gnu/linux) MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Mailing-List: contact binutils-help@sourceware.org; run by ezmlm Precedence: bulk List-Id: List-Subscribe: List-Archive: List-Post: List-Help: , Sender: binutils-owner@sourceware.org X-SW-Source: 2011-02/txt/msg00175.txt.bz2 On Feb 14, 2011, David Daney wrote: > Current MIPS 32-bit ABIs (both o32 and n32) are restricted to 2GB of > user virtual memory space. This is due the way MIPS32 memory space is > segmented. Only the range from 0..2^31-1 is available. Pointer > values are always sign extended. > The proposed new ABI would only be available on MIPS64 platforms. It > would be identical to the current MIPS n32 ABI *except* that pointers > would be zero-extended rather than sign-extended when resident in > registers. FTR, I don't really know why my Yeeloong is limited to 31-bit addresses, and I kind of hoped an n32 userland would improve that WRT o32, without wasting memory with longer pointers like n64 would. So, sorry if this is a dumb question, but wouldn't it be much easier to keep on using sign-extended addresses, and just make sure the kernel never allocates a virtual memory range that crosses a sign-bit change, or whatever other reason there is for addresses to be limited to the positive 2GB range in n32? -- Alexandre Oliva, freedom fighter http://FSFLA.org/~lxoliva/ You must be the change you wish to see in the world. -- Gandhi Be Free! -- http://FSFLA.org/ FSF Latin America board member Free Software Evangelist Red Hat Brazil Compiler Engineer