Xen devel - Apr 2010 - Fwd: [Xen-users] XenVGAPassthrough Xen 4.0.0

Forwarding to devel list (guess it''s better to post here)

-------- Original Message --------
Subject: [Xen-users] XenVGAPassthrough Xen 4.0.0
Date: Thu, 15 Apr 2010 15:58:58 +0200
From: Daniel Spies <daniel.spies@fuceekay.com>
To: <xen-users@lists.xensource.com>
Reply-To: daniel.spies@fuceekay.com

Hello,

I''m searching for a solution to execute Windows 3D applications (e.g.
Games or CAD software) through Linux for about 3 years. I tried plenty of
things, VirtualBox and VMWare DirectX support, Xen VGA pass-through (there
once was a patch) etc, etc. When I recently visited a Citrix event there
was a small demo/introduction of XenClient which is capable of running 2
(or more?) operating systems on top of a hypervisor, both supporting full
3D graphics. Things I found out (it''s still in private beta, expected
to
be
public beta in 4 weeks):

- Capable of doing 3D on both domU''s
- Very limited in hardware choice (due to native hardware emulation on
passive O/S?)
- Capable of doing "Floating/Seamless Windows" (2D/3D? see [1])
- Not FOSS :(
- I expect this system to require the Intel VT-d or AMD IOMMU (AMD Vi?)

A few questions arise:

[2] states that Xen 4.0.0 will/does support VGA pass-through to HVM
guests. Does this pass-through mean to completely lose the device in the
host system (dom0)? That would mean you''d neither be possible to have a
windowed guest on top of the host GUI (!) nor would you be able to stream
windows of the client to the host (like on [1]). I assume the O/S
switching
like in the video would be possible through the hot-plug capabilities of
Xen. This makes me assume you''d have to emulate the VGA adapter on the
passive client as long it is not the "focused" one to keep the O/S
happy
(otherwise it would still try to access the device). This again means
you''d
have emulated/virtual devices for each single peace of hardware in the
world to gain full compatibility (which again may be the reason for the
short list of supported devices from Citrix). Please correct me if any of
the above thoughts are foolish or simply wrong.

I guess the summarized question to my twisted thoughts would be: May I (be
it Xen or not) use my PCIe VGA adapter on both, the host and the guest
system at the same time? If that doesn''t make sense (I am still at the
beginnings of very hardware specific knowledge): May I get the graphical
data that an application sends to the VGA adapter (from any window) in the
guest, and stream it to the hosts VGA adapter/driver? Guess it would also
help if anyone had an idea on how those seamless windows are done.

Thanks for any comment! Please excuse the length of the message.

Cheers,
Daniel

[1] http://www.youtube.com/watch?v=kxoWxjThzo0
[2] http://wiki.xensource.com/xenwiki/XenVGAPassthrough


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