I posted this on the Xen Users mailing list, thought I'd try for a
different perspective from Gentoo users.
I'm doing a fresh install of Xen on an AMD64 using Gentoo. I have an
nvidia graphics card. I want Dom0 to be a minimal system, installed
without Xorg or any other GUI applications. I'm hoping to set up Xen
with (at least) 3 guest domains -- one running servers for the network
(ntp, dhcp, bind, yp, etc.), one guest domain running my desktop with
Xorg and the third guest domain to be used for development & testing.
What I'm hoping to find out is --
1. does the above make sense?
2. I want to access the X-server on the desktop domU directly on tty7.
Is this possible? If so, how can I do this?
3. what are the things I need to watch out for?
4. Any list members running Xen?
I've done some research and I'm aware I have to disable tls and compile
the system with specific compiler flags. If anyone has pointers to
documentation specific to what I want to do, that would be much
One of the responses I received on the Xen-Users mailing list (from
Matts Peterssons, quote) --
| No. The X-server needs to be the OWNER of all the graphics card, and
your Dom0 takes ownership of
| the graphics card very early on. There is two solutions that come to
| You could perhaps use a simple PCI graphics card for the Dom0 console,
and then give the DomU the
| nvidia card, but any shared hardware must be managed by one Domain
only (and everyone else talking
| through that domain to get access). Of course, this assumes that there
is an nVidia driver that works
| under Xen, which I don't think exists (yet) - and I very much doubt
that native kernel graphics drivers
| will work "out of the box" - as they probably do all sorts of "nasty"
things that Xen needs to be aware of.
| Or you can use vncserver/vncviewer to access your desktop machine.
In one of the documents, I read, it indicated that, for example, if I
had 2 PCI network cards, and I wanted to have domU manage one of the
cards directly, there's a way of telling Dom0 to leave the management of
a particular PCI bus/device alone. Is it possible to do something
similar with the AGP adapter bus/card? But, given that I actually get
this to work, how do I go about getting desktop domU to gain control of
tty7 (or whatever, since all consoles are (I believe) controlled by
dom0. In other words, I'd like to have a direct pass-through, or
whatever one might call it.
Could I achieve something similar by installing Xorg in dom0 and domU
and running XDMCP to connect to domU? This would mean a more complicated
package management scenario since Dom0 won't be a minimalist
installation anymore. I guess it all depends on how well the nvidia
drivers play with Xen.
A later response (again from Matts Peterssons, quote) --
| I very much doubt this [having DomU control the nvidia card] will work in actual
| practice [as I once read: In theory, there's no difference between theory and
| practice - in practice there is...] The difficulty would be to have a driver that
| is "Xen-clean" or "Xen-aware". Since the low-level driver for the graphics card
| is a kernel driver, it will have access to all sorts of kernel-internal information,
| and some of this is managed by Xen and should not be used directly by for instance
| a driver. Xen fixes this by patching [changing some macros in header-files is the
| key part of this] the kernel drivers that are included in the kernel itself. But
| the nVidia drivers are closed source, so they are not patchable by this method...
I'd rather have DomU have control of my graphics card and have the
output of Dom0 be redirected to DomU via XDMCP or VNC (for X-Server) and
to virtual network consoles for the rest.
But is this possible?
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