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] Forwarding page faults from within Xen

To: Keir Fraser <Keir.Fraser@xxxxxxxxxxxx>
Subject: Re: [Xen-devel] Forwarding page faults from within Xen
From: Jacob Gorm Hansen <jacob@xxxxxxxx>
Date: Mon, 22 Mar 2004 13:01:16 +0100
Cc: Xen list <xen-devel@xxxxxxxxxxxxxxxxxxxxx>
Delivery-date: Mon, 22 Mar 2004 13:24:42 +0000
Envelope-to: steven.hand@xxxxxxxxxxxx
In-reply-to: <E1B5Nxm-00056s-00@xxxxxxxxxxxxxxxxxxxx>
List-archive: <http://sourceforge.net/mailarchive/forum.php?forum=xen-devel>
List-help: <mailto:xen-devel-request@lists.sourceforge.net?subject=help>
List-id: List for Xen developers <xen-devel.lists.sourceforge.net>
List-post: <mailto:xen-devel@lists.sourceforge.net>
List-subscribe: <https://lists.sourceforge.net/lists/listinfo/xen-devel>, <mailto:xen-devel-request@lists.sourceforge.net?subject=subscribe>
List-unsubscribe: <https://lists.sourceforge.net/lists/listinfo/xen-devel>, <mailto:xen-devel-request@lists.sourceforge.net?subject=unsubscribe>
References: <E1B5Nxm-00056s-00@xxxxxxxxxxxxxxxxxxxx>
Sender: xen-devel-admin@xxxxxxxxxxxxxxxxxxxxx
On Mon, 2004-03-22 at 12:51, Keir Fraser wrote:
> > hi,
> > 

> Well, you need *some* way of executing and informing the domain to
> tell it about the fault. So there has to be *some* pinned
> always-accessible memory to be able to do this. If you get rid of this
> constraint on the guest-OS stack, then you'll still need some other
> memory buffer to store fault info -- there has to be some back
> stop. So I don't think you save yourself any pain.

Hmm, I suppose you are right about that then... I keep forgetting the
price all the luxury features of L4 came at.

> As for network buffers, how would we present the fault to the guest
> OS? The neatest answer to all this that I can see is to use shadow
> page tables and use this to get Xen to log pages as they are dirtied.
> Anything which involves the guest OS itself receiving 'page faults'
> for events which occurred under its feet just sounds hideous to me!
> :-)

Actually, my problem is not as much the network buffer pages, put the
pagetables pointing to them. Right now I identify these and take care of
them specially so that my checkpoint is consistent, but it is a bit
unclear to me what happens if I write-protect them. Will Xen kill me, or
just silently change the protection bits?

Jacob



-------------------------------------------------------
This SF.Net email is sponsored by: IBM Linux Tutorials
Free Linux tutorial presented by Daniel Robbins, President and CEO of
GenToo technologies. Learn everything from fundamentals to system
administration.http://ads.osdn.com/?ad_id=1470&alloc_id=3638&op=click
_______________________________________________
Xen-devel mailing list
Xen-devel@xxxxxxxxxxxxxxxxxxxxx
https://lists.sourceforge.net/lists/listinfo/xen-devel

<Prev in Thread] Current Thread [Next in Thread>