From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id ; Fri, 4 May 2001 11:44:30 -0400 Received: (majordomo@vger.kernel.org) by vger.kernel.org id ; Fri, 4 May 2001 11:44:21 -0400 Received: from ebiederm.dsl.xmission.com ([166.70.28.69]:41328 "EHLO flinx.biederman.org") by vger.kernel.org with ESMTP id ; Fri, 4 May 2001 11:44:09 -0400 To: Alan Cox Cc: torvalds@transmeta.com (Linus Torvalds), beamz_owl@yahoo.com (Edward Spidre), linux-kernel@vger.kernel.org (Kernel Mailing List) Subject: Re: Possible PCI subsystem bug in 2.4 In-Reply-To: From: ebiederm@xmission.com (Eric W. Biederman) Date: 04 May 2001 09:41:51 -0600 In-Reply-To: Alan Cox's message of "Thu, 3 May 2001 19:31:04 +0100 (BST)" Message-ID: User-Agent: Gnus/5.0803 (Gnus v5.8.3) Emacs/20.5 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 Alan Cox writes: > > I suspect it would be safe to round up to the next megabyte, possibly up > > to 64MB or so. But much more would make me nervous. > > Any suggestions? > > I'd go for 1MByte simply because I've not seen an EBDA/NVRAM area that large > stuck at the top of RAM. 1Mb would fix the Dell. (It was only when I saw > your email it suddenely clicked and I grabbed the bootup log) There are a couple of options here. 1) read the MTRRs unless the BIOS is braindead it will set up that area as write-back. At any rate we shouldn't ever try to allocate a pci region that is write-back cached. 2) read the memory locations from the northbridge. It's not possible on every chipset (lack of documentation) but with the linuxBIOS project we code for a couple of them, and we are working on more all of the time. Eric