From: Christoph Egger <Christoph.Egger@xxxxxxx>
Subject: Re: [Xen-devel] [PATCH] xen: make (set|get)_xen_guest_handle available
To: "Keir Fraser" <keir.fraser@xxxxxxxxxxxxx>
Cc: "xen-devel@xxxxxxxxxxxxxxxxxxx" <xen-devel@xxxxxxxxxxxxxxxxxxx>
Date: Thursday, July 30, 2009, 6:34 AM

On Thursday 30 July 2009 12:14:04 Keir Fraser wrote:
> On 30/07/2009 10:12, "Christoph Egger" <Christoph.Egger@xxxxxxx> wrote:
> > Make (set|get)_xen_guest_handle() always available.
> > This avoids code snippets in the guest like this:
> >
> > #if __XEN_ITNERFACE_VERSION__ >= 0x00030201
> > set_xen_guest_handle(hnd, val);
> > #else
> > hnd = val;
> > #endif
>
> Actually I don't see why you'd have code like this. *You*, the guest, gets
> to specify __XEN_INTERFACE_VERSION__ -- that is the point of it -- so
> ifdef'ing based on it in the guest is stupid.
>
> Just specify __XEN_INTERFACE_VERSION__ to be recent enough to have the
> guest handles, and then remove your ifdefs. Simple.

The point is to keep backward compatibility. The patch makes Xen more friendly
with using the old non-structured guest handler if the user wants.

NetBSD offers both way to build & run it with either using the old or new
interface. This allows a smooth migration.

Christoph


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