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RE: [Xen-devel] Paravirtualised drivers for fully virtualised domains

To: "Steven Smith" <sos22-xen@xxxxxxxxxxxxx>, <xen-devel@xxxxxxxxxxxxxxxxxxx>
Subject: RE: [Xen-devel] Paravirtualised drivers for fully virtualised domains
From: "Nakajima, Jun" <jun.nakajima@xxxxxxxxx>
Date: Wed, 26 Jul 2006 15:35:27 -0700
Cc: sos22@xxxxxxxxxxxxx
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Thread-topic: [Xen-devel] Paravirtualised drivers for fully virtualised domains
Steven Smith wrote:
> I've just put an updated version of these patches up at
> http://www.cl.cam.ac.uk/~sos22/pv-on-hvm/rev2 .  There's also an
> equivalent single big patch at
> http://www.cl.cam.ac.uk/~sos22/pv-on-hvm/rev2.combined .  Thank you to
> everyone who gave feedback on the previous version.
> The main changes since last time are:
> -- Support for SMP guests
> -- Support for 64 bit guests on a 64 bit hypervisor
> -- Partial support for 32 bit guests on a 64 bit hypervisor: the
>    network interface works, but the block device doesn't.
> The block device can be made to work by #define'ing ALIEN_INTERFACES
> in blkif.h, but drivers compiled in that way won't work with 32 on 32.
> The problem here is that blkif_request_t contains extra padding in 64
> bit builds, and so is a different size, and so the block ring layout
> is different.

When do you expect this be in the unstable tree? Or which issues must be
resolved befor that?

> Other structures with similar problems are handled either by run time
> tests in the drivers (shared_info_t) or translation wrappers in the
> hypervisor (xen_feature_info_t, xen_add_to_physmap_t), but trying to
> do this for the block rings would require far more painful and
> extensive surgery.  I'm inclined to stick with multiply compiling the
> frontend drivers in the short term, although it'll obviously need
> doing in a slightly less grotty way.
> Steven.

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