From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1754748AbYJEByK (ORCPT ); Sat, 4 Oct 2008 21:54:10 -0400 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S1752907AbYJEBx5 (ORCPT ); Sat, 4 Oct 2008 21:53:57 -0400 Received: from terminus.zytor.com ([198.137.202.10]:59157 "EHLO terminus.zytor.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1752857AbYJEBx4 (ORCPT ); Sat, 4 Oct 2008 21:53:56 -0400 Message-ID: <48E81DED.7050902@zytor.com> Date: Sat, 04 Oct 2008 18:52:45 -0700 From: "H. Peter Anvin" User-Agent: Thunderbird 2.0.0.14 (X11/20080501) MIME-Version: 1.0 To: Yinghai Lu CC: Ingo Molnar , Thomas Gleixner , Andrew Morton , linux-kernel@vger.kernel.org Subject: Re: [PATCH 2/3] x86: mtrr_cleanup: first 1M should be coverred in var mtrrs References: <1223157033-30217-1-git-send-email-yhlu.kernel@gmail.com> <1223157033-30217-2-git-send-email-yhlu.kernel@gmail.com> <48E80E60.8080106@zytor.com> <86802c440810041849g421ff524pf987f6c872e1d12a@mail.gmail.com> In-Reply-To: <86802c440810041849g421ff524pf987f6c872e1d12a@mail.gmail.com> Content-Type: text/plain; charset=UTF-8; format=flowed Content-Transfer-Encoding: 7bit Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Yinghai Lu wrote: >> The first 1 MB is a total don't care for the variable MTRRs -- they don't >> have to be covered *or* uncovered, since the entire first 1 MB is addressed >> by fixed MTRRs. > > so it is safe to put it in WB, and can be spare some regs because it > start from base 0. Yes, my point was that you can make those whatever you want. It doesn't have to be WB; it can be any value. >> In practice, it is *likely* that you're going to want to merge it with a WB >> MTRR, but with various vendors doing all kinds of strange things on >> EFI-damaged platforms, it may not always be that way. > > EFI will not use fixed-mtrr for first 1M? and not cover first 1M in > var mtrr with WB? that will run out mtrr regs.. There are some systems which, apparently, don't have RAM there. Don't ask me how or why. -hpa