From mboxrd@z Thu Jan 1 00:00:00 1970 Received: with ECARTIS (v1.0.0; list linux-mips); Wed, 05 Oct 2005 14:21:27 +0100 (BST) Received: from zproxy.gmail.com ([64.233.162.199]:52012 "EHLO zproxy.gmail.com") by ftp.linux-mips.org with ESMTP id S3465666AbVJENVK convert rfc822-to-8bit (ORCPT ); Wed, 5 Oct 2005 14:21:10 +0100 Received: by zproxy.gmail.com with SMTP id j2so95318nzf for ; Wed, 05 Oct 2005 06:20:59 -0700 (PDT) DomainKey-Signature: a=rsa-sha1; q=dns; c=nofws; s=beta; d=gmail.com; h=received:message-id:date:from:reply-to:to:subject:cc:in-reply-to:mime-version:content-type:content-transfer-encoding:content-disposition:references; b=WTCNu1jze6HvHhxT1/om2R18JfKQ2CdOQX3kunIVPlgUYFW1+q+v/d/tixasiwIMfXsSTUnMBk7f1BU04PXVjaZdetDX/hxOaYTeDGOx8BxsnalBuaIjDu/x1ghQ8wk5whX2evUqP1ZySf6jM4fnAUSOepW0BLUH+uJ20aqowHs= Received: by 10.36.252.78 with SMTP id z78mr520494nzh; Wed, 05 Oct 2005 06:20:59 -0700 (PDT) Received: by 10.36.49.3 with HTTP; Wed, 5 Oct 2005 06:20:59 -0700 (PDT) Message-ID: Date: Wed, 5 Oct 2005 15:20:59 +0200 From: Franck Reply-To: Franck To: "Kevin D. Kissell" Subject: Re: [PATCH] Add support for 4KS cpu. Cc: "Maciej W. Rozycki" , Ralf Baechle , linux-mips@linux-mips.org In-Reply-To: <4343A0FE.9080808@mips.com> MIME-Version: 1.0 Content-Type: text/plain; charset=ISO-8859-1 Content-Transfer-Encoding: 8BIT Content-Disposition: inline References: <434277D5.1090603@mips.com> <4343A0FE.9080808@mips.com> Return-Path: X-Envelope-To: <"|/home/ecartis/ecartis -s linux-mips"> (uid 0) X-Orcpt: rfc822;linux-mips@linux-mips.org Original-Recipient: rfc822;linux-mips@linux-mips.org X-archive-position: 9149 X-ecartis-version: Ecartis v1.0.0 Sender: linux-mips-bounce@linux-mips.org Errors-to: linux-mips-bounce@linux-mips.org X-original-sender: vagabon.xyz@gmail.com Precedence: bulk X-list: linux-mips 2005/10/5, Kevin D. Kissell : > I'm personally not a big believer in security-through-obscurity, > but there are those, both inside and outside MIPS, who felt that > the security of SmartMIPS cores would be enhanced if we didn't > give away all of the details. As a consequence, we put off > publishing the nitty-gritty details of SmartMIPS for quite a while. > I note that we now have the programmers' manual on-line at www.mips.com, > so I guess I'm implicitly cleared to discuss it in at least that level > of detail. > well, I agree with you on "security-through-obscurity" point. From outside, I feel like MIPS has a lot of things to _hide_ athough that's not a good feeling for security systems. Anyways... > A key element of SmartMIPS that allows for a ~2x speedup for > crypto codes that rely on extended precision math (RSA, ECC) > is the combination of an extension to the Hi/Lo accumulator > (called "ACX") with a special extract-and-reduce instruction > ("MFLHXU"). If one wants to use that in Linux - or at least, > if one wants to allow more than one thread to be able to use > it at a time - one needs to save/restore ACX on the kernel > stackframe, along with Hi and Lo. > Correct. I must at least add this in the patch. I'll do it soon. Thanks for enlight this. -- Franck