Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1753738AbXFLVbw (ORCPT ); Tue, 12 Jun 2007 17:31:52 -0400 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S1751265AbXFLVbp (ORCPT ); Tue, 12 Jun 2007 17:31:45 -0400 Received: from lucidpixels.com ([75.144.35.66]:55979 "EHLO lucidpixels.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1750747AbXFLVbo (ORCPT ); Tue, 12 Jun 2007 17:31:44 -0400 Date: Tue, 12 Jun 2007 17:31:44 -0400 (EDT) From: Justin Piszcz X-X-Sender: jpiszcz@p34.internal.lan To: Pavel Machek cc: Jesse Barnes , Andi Kleen , linux-kernel@vger.kernel.org, "Eric W. Biederman" Subject: Re: [PATCH] trim memory not covered by WB MTRRs In-Reply-To: <20070612213020.GA13747@elf.ucw.cz> Message-ID: References: <200706071530.51552.jesse.barnes@intel.com> <20070612145007.GA5986@ucw.cz> <200706120829.21465.jesse.barnes@intel.com> <20070612213020.GA13747@elf.ucw.cz> MIME-Version: 1.0 Content-Type: TEXT/PLAIN; charset=US-ASCII; format=flowed Sender: linux-kernel-owner@vger.kernel.org X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 1813 Lines: 48 On Tue, 12 Jun 2007, Pavel Machek wrote: > Hi! > >>>> On some machines, buggy BIOSes don't properly setup WB MTRRs to >>>> cover all available RAM, meaning the last few megs (or even gigs) >>>> of memory will be marked uncached. Since Linux tends to allocate >>>> from high memory addresses first, this causes the machine to be >>>> unusably slow as soon as the kernel starts really using memory >>>> (i.e. right around init time). >>>> >>>> + if ((highest_addr >> PAGE_SHIFT) != end_pfn) { >>>> + printk(KERN_WARNING "***************\n"); >>>> + printk(KERN_WARNING "**** WARNING: likely BIOS bug\n"); >>>> + printk(KERN_WARNING "**** MTRRs don't cover all of " >>>> + "memory, trimmed %ld pages\n", end_pfn - >>>> + (highest_addr >> PAGE_SHIFT)); >>>> + printk(KERN_WARNING "***************\n"); >>>> + end_pfn = highest_addr >> PAGE_SHIFT; >>> >>> Missing 4K of memory is not worth 4K of junk in syslog per boot. Can >>> you drop the stars and stop shouting? >> >> How missing about 1G of memory? We already discussed this, and Andi and >> Venki felt that either a panic or a really obnoxious message was the >> way to go... > > Just use panic, then. > Pavel, > who still thinks anyone missing 1GB of ram will not miss > friendly notice in dmesg, even if it goes without 20 stars. > > -- > (english) http://www.livejournal.com/~pavelmachek > (cesky, pictures) http://atrey.karlin.mff.cuni.cz/~pavel/picture/horses/blog.html > What is wrong with Jesse's patch? I've been using it for quite a few days now, no issues. Justin. - 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/