From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1752000AbXLKVVh (ORCPT ); Tue, 11 Dec 2007 16:21:37 -0500 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S1753440AbXLKVV1 (ORCPT ); Tue, 11 Dec 2007 16:21:27 -0500 Received: from moutng.kundenserver.de ([212.227.126.174]:53122 "EHLO moutng.kundenserver.de" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1754132AbXLKVVZ convert rfc822-to-8bit (ORCPT ); Tue, 11 Dec 2007 16:21:25 -0500 From: Arnd Bergmann To: linuxppc-dev@ozlabs.org Subject: Re: [RFC][POWERPC] Provide a way to protect 4k subpages when using 64k pages Date: Tue, 11 Dec 2007 22:21:15 +0100 User-Agent: KMail/1.9.6 (enterprise 0.20070907.709405) Cc: Christoph Hellwig , Paul Mackerras , linux-kernel@vger.kernel.org References: <18264.58263.818005.757831@cargo.ozlabs.ibm.com> <20071211155305.GA28055@lst.de> In-Reply-To: <20071211155305.GA28055@lst.de> X-Face: I@=L^?./?$U,EK.)V[4*>`zSqm0>65YtkOe>TFD'!aw?7OVv#~5xd\s,[~w]-J!)|%=]>=?utf-8?q?+=0A=09=7EohchhkRGW=3F=7C6=5FqTmkd=5Ft=3FLZC=23Q-=60=2E=60Y=2Ea=5E?= =?utf-8?q?3zb?=) =?utf-8?q?+U-JVN=5DWT=25cw=23=5BYo0=267C=26bL12wWGlZi=0A=09=7EJ=3B=5Cwg?= =?utf-8?q?=3B3zRnz?=,J"CT_)=\H'1/{?SR7GDu?WIopm.HaBG=QYj"NZD_[zrM\Gip^U MIME-Version: 1.0 Content-Type: text/plain; charset="iso-8859-1" Content-Transfer-Encoding: 8BIT Content-Disposition: inline Message-Id: <200712112221.17697.arnd@arndb.de> X-Provags-ID: V01U2FsdGVkX1/QLBTEXWwyiVm8MqZfDInVWR2UCE0Kdj0WfSz G/wZncvWqqXVuvegqf7rqILjxJQGVOvZ9AeVexsT1tXQszWP13 QNKR6ASBaIKuHOWTlV7RA== Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Tuesday 11 December 2007, Christoph Hellwig wrote: > Using 4k pages should basically be a pre-process flag > (which it already is as an implementation detail in your patch), and > thus the proper way to mark it should be a personality flag.  This > also means it could be implied by certain personalities, e.g. powerpc > 32bit for full compatiblity.   All these process would use plain mmap/ > mprotect to deal with the subpage protections. If you want to make it a per-process flag, wouldn't a prctl bit be more appropriate than a personality flag? That way you could at least set it independent from other personality settings. > At least ia64 and mips have multiple pages sizes already and I suspect > more architectures will grow support for it. Another related option might be the alternative page table layouts that Martin Schwidefsky has implemented for concurrent 2/3/4-level page tables on s390. Arnd <><