Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S264122AbUDOQiV (ORCPT ); Thu, 15 Apr 2004 12:38:21 -0400 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S264319AbUDOQiV (ORCPT ); Thu, 15 Apr 2004 12:38:21 -0400 Received: from colin2.muc.de ([193.149.48.15]:28690 "HELO colin2.muc.de") by vger.kernel.org with SMTP id S264122AbUDOQiT (ORCPT ); Thu, 15 Apr 2004 12:38:19 -0400 Date: 15 Apr 2004 18:38:18 +0200 Date: Thu, 15 Apr 2004 18:38:18 +0200 From: Andi Kleen To: "Eric W. Biederman" Cc: Andi Kleen , Terence Ripperda , linux-kernel@vger.kernel.org Subject: Re: PAT support Message-ID: <20040415163818.GA54491@colin2.muc.de> References: <1KifY-uA-7@gated-at.bofh.it> Mime-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: User-Agent: Mutt/1.4.1i Sender: linux-kernel-owner@vger.kernel.org X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 938 Lines: 22 > This would also be extremely useful on machines with large amounts > of memory, for write-back mappings. With large amounts but odd sized > entries it becomes extremely tricky to map all of the memory using > mtrrs. Yes agreed. I already had vendors complaining about this. But for this it will need some more work - the MTRRs need to be fully converted to PAT and then disabled (because MTRRs have higher priority than PAT). Doing so is a lot more risky than what Terrence's patch does currently though. But longer term we will need it. Also it will still need to handle overlapping ranges. I suppose it will need some simple rules like: converting from UC to WC is always ok. -Andi - 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/