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Re: [Xen-devel] [patch] ACM ops interface

To: Keir Fraser <Keir.Fraser@xxxxxxxxxxxx>
Subject: Re: [Xen-devel] [patch] ACM ops interface
From: Hollis Blanchard <hollisb@xxxxxxxxxx>
Date: Thu, 08 Jun 2006 12:59:55 -0500
Cc: xen-devel@xxxxxxxxxxxxxxxxxxx, Reiner Sailer <sailer@xxxxxxxxxx>, xen-ppc-devel <xen-ppc-devel@xxxxxxxxxxxxxxxxxxx>
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On Thu, 2006-06-08 at 17:11 +0100, Keir Fraser wrote:
> On 8 Jun 2006, at 16:01, Hollis Blanchard wrote:
> 
> > If the ACM ops were always passed in a union, we could replace the 
> > first
> > switch with a single copy_from_user(), and also guarantee that
> > "interface_version" is always in the right place (it's only there
> > coincidentally now). What do you think?
> 
> The interface was deliberately changed away from that style for 
> consistency with other hypercalls. Also to allow larger argument 
> structures to be added to the interface later without breaking backward 
> compatibility (inflating the size of the union).

Ah, that makes sense. Too bad it will uglify the already unpleasant
handle hacks PPC needs to do.

Are you planning to do something similar for the dom0_op structure?

-- 
Hollis Blanchard
IBM Linux Technology Center


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