This is an archived copy of the Xen.org mailing list, which we have preserved to ensure that existing links to archives are not broken. The live archive, which contains the latest emails, can be found at http://lists.xen.org/
Home Products Support Community News


Re: [Xen-devel] scrubbing free'd pages

To: James Harper <james.harper@xxxxxxxxxxxxxxxx>, Rafal Wojtczuk <rafal@xxxxxxxxxxxxxxxxxxxxxx>
Subject: Re: [Xen-devel] scrubbing free'd pages
From: Keir Fraser <keir.fraser@xxxxxxxxxxxxx>
Date: Tue, 25 May 2010 14:39:48 +0100
Cc: "xen-devel@xxxxxxxxxxxxxxxxxxx" <xen-devel@xxxxxxxxxxxxxxxxxxx>
Delivery-date: Tue, 25 May 2010 06:40:54 -0700
Envelope-to: www-data@xxxxxxxxxxxxxxxxxxx
In-reply-to: <AEC6C66638C05B468B556EA548C1A77D01996B12@trantor>
List-help: <mailto:xen-devel-request@lists.xensource.com?subject=help>
List-id: Xen developer discussion <xen-devel.lists.xensource.com>
List-post: <mailto:xen-devel@lists.xensource.com>
List-subscribe: <http://lists.xensource.com/mailman/listinfo/xen-devel>, <mailto:xen-devel-request@lists.xensource.com?subject=subscribe>
List-unsubscribe: <http://lists.xensource.com/mailman/listinfo/xen-devel>, <mailto:xen-devel-request@lists.xensource.com?subject=unsubscribe>
Sender: xen-devel-bounces@xxxxxxxxxxxxxxxxxxx
Thread-index: Acr8CNS19yMRz6p4QwKoc+hHZsXMAAAAVMFjAAEQV8AAAFVKxg==
Thread-topic: [Xen-devel] scrubbing free'd pages
User-agent: Microsoft-Entourage/
On 25/05/2010 14:33, "James Harper" <james.harper@xxxxxxxxxxxxxxxx> wrote:

>> Other memory pages the domain freeing the
>> pages must scrub them itself before freeing them back to Xen.
> Is that true for a HVM domain making a decrease_reservation hypercall?
> If so I should modify my code accordingly...

Yes you should.

> it also means I need to
> know if the page I'm decreasing is an unpopulated PoD page or not too.

Certainly you could avoid it in that case. Actually I think the PoD code can
detect and reclaim allocated-but-zeroed pages however. But not sure if you
really have to rely on that or not.

 -- Keir

Xen-devel mailing list