Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1753517AbYFYUDS (ORCPT ); Wed, 25 Jun 2008 16:03:18 -0400 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S1751617AbYFYUDI (ORCPT ); Wed, 25 Jun 2008 16:03:08 -0400 Received: from one.firstfloor.org ([213.235.205.2]:43334 "EHLO one.firstfloor.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751476AbYFYUDH (ORCPT ); Wed, 25 Jun 2008 16:03:07 -0400 Date: Wed, 25 Jun 2008 22:14:27 +0200 From: Andi Kleen To: Keir Fraser Cc: Andi Kleen , Jeremy Fitzhardinge , Mark McLoughlin , xen-devel , Eduardo Habkost , LKML , Stephen Tweedie Subject: Re: [Xen-devel] Re: [PATCH 00 of 36] x86/paravirt: groundwork for 64-bit Xen support Message-ID: <20080625201427.GE6708@one.firstfloor.org> References: <20080625191315.GD6708@one.firstfloor.org> Mime-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: User-Agent: Mutt/1.4.2.1i Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 993 Lines: 26 > There are obviously no x64 boxes around at the moment with >1TB of regular > shared memory, since no CPUs have more than 40 address lines. 100+TB RAM is That's actually not true. > surely years away. Yes, but why build something non scalable now that you have to fix in a few years? Especially when it comes with "i have no justification" in the commit log. > > So far we always that 64bit Linux can support upto 1/4*max VA memory. > > With your change that formula would be not true anymore. > > Does the formula have any practical significance? Yes, because getting more than 48bits of VA will be extremly costly in terms of infrastructure and assuming continuing growth rates and very large machines 46bits is not all that much. -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/