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] passing hypercall parameters by pointer

To: "Keir Fraser" <Keir.Fraser@xxxxxxxxxxxx>, "Jimi Xenidis" <jimix@xxxxxxxxxxxxxx>
Subject: RE: [Xen-devel] passing hypercall parameters by pointer
From: "Ian Pratt" <m+Ian.Pratt@xxxxxxxxxxxx>
Date: Fri, 19 Aug 2005 13:41:04 +0100
Cc: "Tian, Kevin" <kevin.tian@xxxxxxxxx>, xen-devel@xxxxxxxxxxxxxxxxxxx
Delivery-date: Fri, 19 Aug 2005 12:39:15 +0000
Envelope-to: www-data@xxxxxxxxxxxxxxxxxxx
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/cgi-bin/mailman/listinfo/xen-devel>, <mailto:xen-devel-request@lists.xensource.com?subject=subscribe>
List-unsubscribe: <http://lists.xensource.com/cgi-bin/mailman/listinfo/xen-devel>, <mailto:xen-devel-request@lists.xensource.com?subject=unsubscribe>
Sender: xen-devel-bounces@xxxxxxxxxxxxxxxxxxx
Thread-index: AcWkt3Cu9FDkZ4M2SPaZ8ap5p+ptBwAAozCA
Thread-topic: [Xen-devel] passing hypercall parameters by pointer
> This is all potentially fixable before 3.0 final. Paravirt 
> x86 can continue to use guest virtual addresses. The idea 
> would be that the registration scheme would essentially 
> create a parameter-passing 'address space' into which you 
> hook pages of memory. On x86 we would map the address space 
> onto regions of kernel va space. On other arches we would map 
> the address space onto physical addresses that get mapped 
> into Xen's va space. 
> get_user/put_user/copy_from_user/copy_to_user will take guest 
> addresses that point into this parameter-passing address space.
> 
> At least we can scope it out by doing a few hypercalls to 
> start with -- probably dom0_ops first and see how it pans 
> out. I think it will work quite well...

I'd be inclined to first go after the ops that are needed for the
paravirtualized drivers (mem_op, grantab_op). Perhaps people could post
a few patch examples for dicsussion?

NB: This in no way represents a commitment to get this into 3.0-final.
Let's have a look at the patches and decide.

[Right now, anything that isn't fixing bugs or sorting out xenbus/tools
is actually a distraction]

Ian


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