From: Christoph Egger <Christoph.Egger@xxxxxxx>
Subject: Re: [Xen-devel] [PATCH] xen: make (set|get)_xen_guest_handle available
To: "Boris Derzhavets" <bderzhavets@xxxxxxxxx>
Cc: "xen-devel@xxxxxxxxxxxxxxxxxxx" <xen-devel@xxxxxxxxxxxxxxxxxxx>, "Keir Fraser" <keir.fraser@xxxxxxxxxxxxx>
Date: Thursday, July 30, 2009, 7:55 AM

Hi Boris,

this is the history:

NetBSD 2.0 got Xen 1.2 support (both Dom0 and DomU)
NetBSD 3.0 got Xen 2 support, dropped Xen 1.2 support (both Dom0 and DomU)
NetBSD 4.0 got Xen 3.0/3.1 support 32bit only, kept Xen 2 support (both Dom0
and DomU)
NetBSD 5.0 got Xen 3.x support (both 32bit and 64bit), kept Xen 2 support
(both Dom0 and DomU)
NetBSD-current dropped Xen 2 support, about to move to new interface.

Christoph

On Thursday 30 July 2009 13:16:00 Boris Derzhavets wrote:
> May the recent version of NetBSD run as PV guest ?
> Sorry, for stupid question.
> Boris.
>
> --- On Thu, 7/30/09, Christoph Egger <Christoph.Egger@xxxxxxx> wrote:
>
> 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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