From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1765435AbXGYXXO (ORCPT ); Wed, 25 Jul 2007 19:23:14 -0400 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S1760035AbXGYXW7 (ORCPT ); Wed, 25 Jul 2007 19:22:59 -0400 Received: from gate.crashing.org ([63.228.1.57]:57862 "EHLO gate.crashing.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1757034AbXGYXW6 (ORCPT ); Wed, 25 Jul 2007 19:22:58 -0400 Subject: Re: pte_offset_map for ppc assumes HIGHPTE From: Benjamin Herrenschmidt To: Andreas Schwab Cc: Satya , linuxppc-dev@ozlabs.org, linux-kernel@vger.kernel.org, linux-mm@kvack.org In-Reply-To: References: Content-Type: text/plain Date: Thu, 26 Jul 2007 09:22:45 +1000 Message-Id: <1185405765.5439.371.camel@localhost.localdomain> Mime-Version: 1.0 X-Mailer: Evolution 2.10.1 Content-Transfer-Encoding: 7bit Sender: linux-kernel-owner@vger.kernel.org X-Mailing-List: linux-kernel@vger.kernel.org On Thu, 2007-07-26 at 01:18 +0200, Andreas Schwab wrote: > Satya writes: > > > hello, > > The implementation of pte_offset_map() for ppc assumes that PTEs are > > kept in highmem (CONFIG_HIGHPTE). There is only one implmentation of > > pte_offset_map() as follows (include/asm-ppc/pgtable.h): > > > > #define pte_offset_map(dir, addr) \ > > ((pte_t *) kmap_atomic(pmd_page(*(dir)), KM_PTE0) + pte_index(addr)) > > > > Shouldn't this be made conditional according to CONFIG_HIGHPTE is > > defined or not > > kmap_atomic is always defined with or without CONFIG_HIGHPTE. > > > (as implemented in include/asm-i386/pgtable.h) ? > > I don't think that needs it either. Depends... if you have CONFIG_HIGHMEM and not CONFIG_HIGHPTE, you are wasting time going through kmap_atomic unnecessarily no ? it will probably not do anything because the PTE page is in lowmem but still... Ben.