WARNING - OLD ARCHIVES

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/
   
 
 
Xen 
 
Home Products Support Community News
 
   
 

xen-devel

Re: [Xen-devel] [PATCH 1/2] PV hugepages - Xen patch

To: Dave McCracken <dcm@xxxxxxxx>, <xen-devel@xxxxxxxxxxxxxxxxxxx>
Subject: Re: [Xen-devel] [PATCH 1/2] PV hugepages - Xen patch
From: Keir Fraser <keir.fraser@xxxxxxxxxxxxx>
Date: Fri, 03 Oct 2008 09:58:32 +0100
Cc:
Delivery-date: Fri, 03 Oct 2008 01:58:57 -0700
Envelope-to: www-data@xxxxxxxxxxxxxxxxxxx
In-reply-to: <200810021826.11939.dcm@xxxxxxxx>
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: AcklNjXtdIFl15EpEd26uwAWy6hiGQ==
Thread-topic: [Xen-devel] [PATCH 1/2] PV hugepages - Xen patch
User-agent: Microsoft-Entourage/11.4.0.080122
Some issues:
 * You need to check return value of get_page_from_pagenr() on every page of
the superpage. Any one of them can fail, causing you to undo your work so
far and then fail.
 * You need to get_page_type(PGT_writable) on every page if the superpage
mapping asserts _PAGE_RW. Otherwise the guest is getting write access
without that being asserted in the reference counts.
 * Look at get_page_from_l1e() for an example of how this is done for a
single page. You need to do similar work for every page of the super-page.
 * This surely breaks save/restore, since the restore code is not
superpage-aware.

 -- Keir

On 3/10/08 00:26, "Dave McCracken" <dcm@xxxxxxxx> wrote:

> 
> This patch enables support of hugepages in a pv Xen environment.  It is
> against the latest xen unstable tree on http://xenbits.xensource.com.
> 
> The patch assumes the guest is passing a physically aligned hugepage.  It does
> reference counting on all the underlying pages.
> 
> Dave McCracken
> Oracle Corp.
> _______________________________________________
> Xen-devel mailing list
> Xen-devel@xxxxxxxxxxxxxxxxxxx
> http://lists.xensource.com/xen-devel



_______________________________________________
Xen-devel mailing list
Xen-devel@xxxxxxxxxxxxxxxxxxx
http://lists.xensource.com/xen-devel