From mboxrd@z Thu Jan 1 00:00:00 1970 Return-path: Received: from smtp.citrix.com ([66.165.176.89]) by merlin.infradead.org with esmtps (Exim 4.80.1 #2 (Red Hat Linux)) id 1VhPft-0006e6-Ay for kexec@lists.infradead.org; Fri, 15 Nov 2013 20:07:30 +0000 Message-ID: <52867EE6.7080205@citrix.com> Date: Fri, 15 Nov 2013 20:07:02 +0000 From: David Vrabel MIME-Version: 1.0 Subject: Re: [PATCH] xen/kexec: Clear unused registers before jumping into an image References: <1384530974-26813-1-git-send-email-daniel.kiper@oracle.com> In-Reply-To: <1384530974-26813-1-git-send-email-daniel.kiper@oracle.com> List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: 7bit Sender: "kexec" Errors-To: kexec-bounces+dwmw2=twosheds.infradead.org@lists.infradead.org To: Daniel Kiper Cc: keir@xen.org, george.dunlap@eu.citrix.com, andrew.cooper3@citrix.com, kexec@lists.infradead.org, xen-devel@lists.xen.org, ebiederm@xmission.com, jbeulich@suse.com On 15/11/13 15:56, Daniel Kiper wrote: > Clear unused registers before jumping into an image. This way > loaded image could not assume that any register has an specific > info about earlier running Xen hypervisor. However, it also > does not mean that the image may expect that a given register > is zeroed. The image MUST assume that every register has a random > value or in other words it is uninitialized or has undefined state. I think this, where the specification (registers undefined) differs from the implementation (registers zeroed), is the worst option. I also think it is more likely for an image to inadvertently rely on a zero value that whatever junk Xen has left behind. David _______________________________________________ kexec mailing list kexec@lists.infradead.org http://lists.infradead.org/mailman/listinfo/kexec