Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S266680AbUJNKwq (ORCPT ); Thu, 14 Oct 2004 06:52:46 -0400 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S270024AbUJNKwq (ORCPT ); Thu, 14 Oct 2004 06:52:46 -0400 Received: from ebiederm.dsl.xmission.com ([166.70.28.69]:27265 "EHLO ebiederm.dsl.xmission.com") by vger.kernel.org with ESMTP id S266680AbUJNKwm (ORCPT ); Thu, 14 Oct 2004 06:52:42 -0400 To: Andi Kleen Cc: Markus Lidel , linux-kernel@vger.kernel.org Subject: Re: question about MTRR areas on x86_64 References: <2M5w2-y8-3@gated-at.bofh.it> From: ebiederm@xmission.com (Eric W. Biederman) Date: 14 Oct 2004 04:49:16 -0600 In-Reply-To: Message-ID: User-Agent: Gnus/5.0808 (Gnus v5.8.8) Emacs/21.2 MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Sender: linux-kernel-owner@vger.kernel.org X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 952 Lines: 23 Andi Kleen writes: > Markus Lidel writes: > > > > Could it be because the machine has too much memory, or is there a bug in the > I2O driver? > > > The problem comes from the BIOS who set up reg00 to be overlapping > over other areas. The Linux MTRR driver cannot deal with overlapping > MTRRs, in fact it is sometimes impossible because it could run > out of registers or violate some of the MTRR restrictions. And the BIOS is using overlapping MTRRs because otherwise it would run out. > It's a long standing problem, eventual fix will be to get rid > of MTRRs completely and only use PAT. But it needs a bit more work. That would be nice to see. Eric - 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/