Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1757123Ab1FUSWv (ORCPT ); Tue, 21 Jun 2011 14:22:51 -0400 Received: from terminus.zytor.com ([198.137.202.10]:57076 "EHLO mail.zytor.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1752125Ab1FUSWv (ORCPT ); Tue, 21 Jun 2011 14:22:51 -0400 References: <1307470409-7654-1-git-send-email-stefano.stabellini@eu.citrix.com> <4DFFCBAD.9040507@linux.intel.com> User-Agent: K-9 Mail for Android In-Reply-To: MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8bit Subject: Re: [PATCH 1/3] x86: calculate precisely the memory needed by init_memory_mapping From: "H. Peter Anvin" Date: Tue, 21 Jun 2011 11:02:43 -0700 To: Stefano Stabellini , "H. Peter Anvin" CC: Stefano Stabellini , "konrad.wilk@oracle.com" , "mingo@elte.hu" , "linux-kernel@vger.kernel.org" , "xen-devel@lists.xensource.com" , "yinghai@kernel.org" Message-ID: <18878791-c24a-4ca7-aa19-904805bc1314@email.android.com> Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 1434 Lines: 41 Stefano Stabellini wrote: >On Mon, 20 Jun 2011, H. Peter Anvin wrote: >> On 06/07/2011 11:13 AM, stefano.stabellini@eu.citrix.com wrote: >> > >> > - remove the extra page added on x86_32 for the fixmap because is >not >> > needed: the PMD entry is already allocated and contiguous for the >whole >> > range (a PMD page covers 4G of virtual addresses) and the pte entry >is >> > already allocated by early_ioremap_init. >> > >> >> Hi Stefano, >> >> I think this is wrong. A PMD page covers *1G* of virtual addresses, >and >> in the 2+2 and 1+3 memory configurations, we may or may not need a >> separate PMD for the fixmap. >> >> Am I missing something? > >You are right, a PMD page covers 1G of virtual addresses so that part >of >the explanation in the comment is wrong. > >The reason why we don't need a separate PMD for the fixmap is that in >both PAE and non-PAE cases the last gigabyte of virtual addresses is >always covered by the initial allocation in head_32.S (swapper_pg_dir >or >initial_pg_pmd). Ok, wasn't sure if Xen used the static allocation or not. -- Sent from my mobile phone. Please excuse my brevity and lack of formatting. -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/