From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1756463Ab2GYKoW (ORCPT ); Wed, 25 Jul 2012 06:44:22 -0400 Received: from mx1.redhat.com ([209.132.183.28]:55537 "EHLO mx1.redhat.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1755533Ab2GYKoV (ORCPT ); Wed, 25 Jul 2012 06:44:21 -0400 Message-ID: <500FCDF3.7080808@redhat.com> Date: Wed, 25 Jul 2012 13:44:03 +0300 From: Avi Kivity User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:13.0) Gecko/20120615 Thunderbird/13.0.1 MIME-Version: 1.0 To: Cong Wang CC: Stefan Bader , Linux Kernel Mailing List , Ingo Molnar , Yinghai Lu , Tejun Heo Subject: Re: x86/mm: Limit 2/4M size calculation to x86_32 References: <5000259D.9020303@canonical.com> In-Reply-To: Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 7bit Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On 07/24/2012 06:52 PM, Cong Wang wrote: >> From 6b679d1af20656929c0e829f29eed60b0a86a74f Mon Sep 17 00:00:00 2001 >> From: Stefan Bader >> Date: Fri, 13 Jul 2012 15:16:33 +0200 >> Subject: [PATCH] x86/mm: Limit 2/4M size calculation to x86_32 >> >> commit 722bc6b (x86/mm: Fix the size calculation of mapping tables) >> did modify the extra space calculation for mapping tables in order >> to make up for the first 2/4M memory range using 4K pages. >> However this setup is only used when compiling for 32bit. On 64bit >> there is only the trailing area of 4K pages (which is already added). >> >> The code was already adapted once for things went wrong on a 8TB >> machine (bd2753b x86/mm: Only add extra pages count for the first memory >> range during pre-allocation early page table space), but it looks a bit >> like it currently would overdo things for 64bit. >> I only noticed while bisecting for the reason I could not make a crash >> kernel boot (which ended up on this patch). >> >> Signed-off-by: Stefan Bader >> Cc: WANG Cong >> Cc: Yinghai Lu >> Cc: Tejun Heo > > Acked-by: Cong Wang > > Sorry for that I was not aware of x86_64 is different with x86 in the > first 2/4M. Why would there be a difference? Shouldn't the IO space at 0xa0000-0x100000 be mapped with uncacheable attributes (or WC for VGA)? If it's done later, it can be done later for both. -- error compiling committee.c: too many arguments to function