From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S932426AbaHGPnB (ORCPT ); Thu, 7 Aug 2014 11:43:01 -0400 Received: from mail-oi0-f51.google.com ([209.85.218.51]:46388 "EHLO mail-oi0-f51.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S932084AbaHGPm7 (ORCPT ); Thu, 7 Aug 2014 11:42:59 -0400 MIME-Version: 1.0 In-Reply-To: References: <1407353564-21478-1-git-send-email-keescook@chromium.org> <1407353564-21478-2-git-send-email-keescook@chromium.org> Date: Thu, 7 Aug 2014 19:42:59 +0400 Message-ID: Subject: Re: [PATCH 1/7] arm: use generic fixmap.h From: Max Filippov To: Nicolas Pitre Cc: Rob Herring , Kees Cook , LKML , Mark Salter , Liu hua , Rabin Vincent , Nikolay Borisov , Leif Lindholm , Tomasz Figa , Doug Anderson , Will Deacon , Laura Abbott , Catalin Marinas , Russell King - ARM Linux , "linux-arm-kernel@lists.infradead.org" Content-Type: text/plain; charset=UTF-8 Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Thu, Aug 7, 2014 at 7:32 PM, Nicolas Pitre wrote: > On Thu, 7 Aug 2014, Rob Herring wrote: > >> On Thu, Aug 7, 2014 at 10:15 AM, Max Filippov wrote: >> > Hi, >> > >> > On Wed, Aug 6, 2014 at 11:32 PM, Kees Cook wrote: >> >> ARM is different from other architectures in that fixmap pages are indexed >> >> with a positive offset from FIXADDR_START. Other architectures index with >> >> a negative offset from FIXADDR_TOP. In order to use the generic fixmap.h >> > >> > Does anybody know if there's any reason why generic fixmap.h uses negative >> > offsets? It complicates things with no obvious benefit if you e.g. try to align >> > virtual address in the fixmap region with physical page color (that's why I've >> > switched xtensa to positive fixmap addressing in v3.17). >> >> No, but each arch doing it differently is even more annoying. > > Why not switching everybody to positive offsets then? I can cook a patch if people agree that that'd be good. -- Thanks. -- Max From mboxrd@z Thu Jan 1 00:00:00 1970 From: jcmvbkbc@gmail.com (Max Filippov) Date: Thu, 7 Aug 2014 19:42:59 +0400 Subject: [PATCH 1/7] arm: use generic fixmap.h In-Reply-To: References: <1407353564-21478-1-git-send-email-keescook@chromium.org> <1407353564-21478-2-git-send-email-keescook@chromium.org> Message-ID: To: linux-arm-kernel@lists.infradead.org List-Id: linux-arm-kernel.lists.infradead.org On Thu, Aug 7, 2014 at 7:32 PM, Nicolas Pitre wrote: > On Thu, 7 Aug 2014, Rob Herring wrote: > >> On Thu, Aug 7, 2014 at 10:15 AM, Max Filippov wrote: >> > Hi, >> > >> > On Wed, Aug 6, 2014 at 11:32 PM, Kees Cook wrote: >> >> ARM is different from other architectures in that fixmap pages are indexed >> >> with a positive offset from FIXADDR_START. Other architectures index with >> >> a negative offset from FIXADDR_TOP. In order to use the generic fixmap.h >> > >> > Does anybody know if there's any reason why generic fixmap.h uses negative >> > offsets? It complicates things with no obvious benefit if you e.g. try to align >> > virtual address in the fixmap region with physical page color (that's why I've >> > switched xtensa to positive fixmap addressing in v3.17). >> >> No, but each arch doing it differently is even more annoying. > > Why not switching everybody to positive offsets then? I can cook a patch if people agree that that'd be good. -- Thanks. -- Max