Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1755086AbZCHWGg (ORCPT ); Sun, 8 Mar 2009 18:06:36 -0400 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S1754451AbZCHWG2 (ORCPT ); Sun, 8 Mar 2009 18:06:28 -0400 Received: from mx2.mail.elte.hu ([157.181.151.9]:52033 "EHLO mx2.mail.elte.hu" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1754450AbZCHWG1 (ORCPT ); Sun, 8 Mar 2009 18:06:27 -0400 Date: Sun, 8 Mar 2009 23:06:09 +0100 From: Ingo Molnar To: "H. Peter Anvin" Cc: Jeremy Fitzhardinge , Andrew Morton , the arch/x86 maintainers , Linux Kernel Mailing List , Xen-devel Subject: Re: [PATCH] xen: core dom0 support Message-ID: <20090308220609.GA23447@elte.hu> References: <1235786365-17744-1-git-send-email-jeremy@goop.org> <20090227212812.26d02f34.akpm@linux-foundation.org> <20090228084254.GA29342@elte.hu> <49A907DD.6010408@goop.org> <20090302120859.GB29015@elte.hu> <49B23907.8030103@goop.org> <20090308110150.GA19151@elte.hu> <49B43F1D.2000400@zytor.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <49B43F1D.2000400@zytor.com> User-Agent: Mutt/1.5.18 (2008-05-17) X-ELTE-VirusStatus: clean X-ELTE-SpamScore: -1.5 X-ELTE-SpamLevel: X-ELTE-SpamCheck: no X-ELTE-SpamVersion: ELTE 2.0 X-ELTE-SpamCheck-Details: score=-1.5 required=5.9 tests=BAYES_00 autolearn=no SpamAssassin version=3.2.3 -1.5 BAYES_00 BODY: Bayesian spam probability is 0 to 1% [score: 0.0000] Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 1170 Lines: 32 * H. Peter Anvin wrote: > Ingo Molnar wrote: > > > > Associativity effects do depend on the kernel image layout > > and on the precise allocations of kernel data structure > > allocations we do during bootup - and they dont really > > change after that. > > > > By the way, there is a really easy way (if a bit time > consuming) to get the actual variability here -- you have to > reboot between runs, even for the same kernel. It makes the > data collection take a long time, but at least it can be > scripted. Since it's the same kernel image i think the only truly reliable method would be to reboot between _different_ kernel images: same instructions but randomly re-align variables both in terms of absolute address and in terms of relative position to each other. Plus randomize bootmem allocs and never-gets-freed-really boot-time allocations. Really hard to do i think ... Ingo -- 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/