Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1763509AbXFATTW (ORCPT ); Fri, 1 Jun 2007 15:19:22 -0400 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S1762024AbXFATTO (ORCPT ); Fri, 1 Jun 2007 15:19:14 -0400 Received: from lucidpixels.com ([75.144.35.66]:41435 "EHLO lucidpixels.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1761466AbXFATTN (ORCPT ); Fri, 1 Jun 2007 15:19:13 -0400 Date: Fri, 1 Jun 2007 15:19:12 -0400 (EDT) From: Justin Piszcz X-X-Sender: jpiszcz@p34.internal.lan To: Jesse Barnes cc: linux-kernel@vger.kernel.org Subject: Re: Intel's response Linux/MTRR/8GB Memory Support / Why doesn't the kernel realize the BIOS has problems and re-map appropriately? In-Reply-To: <200706011210.15808.jbarnes@virtuousgeek.org> Message-ID: References: <200706011210.15808.jbarnes@virtuousgeek.org> 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: 1950 Lines: 46 It works ok on my machine (correctly detects the condition, adjusts end_pfn, and keeps the machine fast), aside from the fact that X won't start. But X won't start? :\ On Fri, 1 Jun 2007, Jesse Barnes wrote: >> and the MTRRs (from /proc/mtrr, from private email): >> >> reg00: base=0x00000000 ( 0MB), size=2048MB: write-back, count=1 >> reg01: base=0x80000000 (2048MB), size=1024MB: write-back, count=1 >> reg02: base=0xc0000000 (3072MB), size= 256MB: write-back, count=1 >> reg03: base=0xcf800000 (3320MB), size= 8MB: uncachable, count=1 >> reg04: base=0xcf700000 (3319MB), size= 1MB: uncachable, count=1 >> reg05: base=0x100000000 (4096MB), size=4096MB: write-back, count=1 >> reg06: base=0x200000000 (8192MB), size= 512MB: write-back, count=1 >> reg07: base=0x220000000 (8704MB), size= 128MB: write-back, count=1 >> >> so the ranges mapped as cacheable are: >> >> 0-3319MB >> 4096-8832MB >> >> leaving 64MB of memory at the top of RAM uncached. What do you want to >> bet that something important (kernel code?) is getting loaded there.. >> >> So essentially it's a BIOS problem, it's not setting up the MTRRs >> properly in order to map all of RAM as cacheable. As Andi says, complain >> to Intel. > > If it's just 64M you'll end up losing, you could try the "[RFC] trim memory > not covered by MTRR WB type" patch I posted yesterday. It won't reinit the > MTRRs (maybe we should) but it will at least prevent your system from > crawling if the BIOS doesn't set them up right. That would at least let you > use most of your memory until the BIOS guys acknowledge that they have a > problem (or we get proper PAT support, which I think would make this problem > go away as well). > > Jesse > - 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/