From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from mail-ob0-f170.google.com (mail-ob0-f170.google.com [209.85.214.170]) by kanga.kvack.org (Postfix) with ESMTP id 468766B0005 for ; Sun, 14 Feb 2016 23:40:33 -0500 (EST) Received: by mail-ob0-f170.google.com with SMTP id jq7so12217548obb.0 for ; Sun, 14 Feb 2016 20:40:33 -0800 (PST) Received: from e32.co.us.ibm.com (e32.co.us.ibm.com. [32.97.110.150]) by mx.google.com with ESMTPS id j138si14841599oih.51.2016.02.14.20.40.32 for (version=TLS1_2 cipher=AES128-SHA bits=128/128); Sun, 14 Feb 2016 20:40:32 -0800 (PST) Received: from localhost by e32.co.us.ibm.com with IBM ESMTP SMTP Gateway: Authorized Use Only! Violators will be prosecuted for from ; Sun, 14 Feb 2016 21:40:32 -0700 Received: from b03cxnp08026.gho.boulder.ibm.com (b03cxnp08026.gho.boulder.ibm.com [9.17.130.18]) by d03dlp01.boulder.ibm.com (Postfix) with ESMTP id 75E211FF001F for ; Sun, 14 Feb 2016 21:28:39 -0700 (MST) Received: from d03av03.boulder.ibm.com (d03av03.boulder.ibm.com [9.17.195.169]) by b03cxnp08026.gho.boulder.ibm.com (8.14.9/8.14.9/NCO v10.0) with ESMTP id u1F4eT4932637146 for ; Sun, 14 Feb 2016 21:40:29 -0700 Received: from d03av03.boulder.ibm.com (localhost [127.0.0.1]) by d03av03.boulder.ibm.com (8.14.4/8.14.4/NCO v10.0 AVout) with ESMTP id u1F4eTmM006674 for ; Sun, 14 Feb 2016 21:40:29 -0700 From: "Aneesh Kumar K.V" Subject: Re: [PATCH V2 07/29] mm: Make vm_get_page_prot arch specific. In-Reply-To: <20160215032124.GB3797@oak.ozlabs.ibm.com> References: <1454923241-6681-1-git-send-email-aneesh.kumar@linux.vnet.ibm.com> <1454923241-6681-8-git-send-email-aneesh.kumar@linux.vnet.ibm.com> <20160215032124.GB3797@oak.ozlabs.ibm.com> Date: Mon, 15 Feb 2016 10:10:24 +0530 Message-ID: <87io1qfux3.fsf@linux.vnet.ibm.com> MIME-Version: 1.0 Content-Type: text/plain Sender: owner-linux-mm@kvack.org List-ID: To: Paul Mackerras Cc: benh@kernel.crashing.org, mpe@ellerman.id.au, linuxppc-dev@lists.ozlabs.org, linux-mm@kvack.org Paul Mackerras writes: > On Mon, Feb 08, 2016 at 02:50:19PM +0530, Aneesh Kumar K.V wrote: >> With next generation power processor, we are having a new mmu model >> [1] that require us to maintain a different linux page table format. >> >> Inorder to support both current and future ppc64 systems with a single >> kernel we need to make sure kernel can select between different page >> table format at runtime. With the new MMU (radix MMU) added, we will >> have to dynamically switch between different protection map. Hence >> override vm_get_page_prot instead of using arch_vm_get_page_prot. We >> also drop arch_vm_get_page_prot since only powerpc used it. > > What's different about ISA v3.0 that means that the protection_map[] > entries need to be different? > > If it's just different bit assignments for things like _PAGE_READ > etc., couldn't we fix this up at early boot time by writing new values > into protection_map[]? Is there a reason why that wouldn't work, or > why you don't want to do that? > Yes, that is other way to do this. But I thought it is easier to have different protection_map array for radix and hash. That made the code more readable. -aneesh -- To unsubscribe, send a message with 'unsubscribe linux-mm' in the body to majordomo@kvack.org. For more info on Linux MM, see: http://www.linux-mm.org/ . Don't email: email@kvack.org