[Spice-devel] Spice agent and LXC

[Charles Ricketts]

Yes, I had seen those options. That was part of why I was asking about the
ucds socket. I found now that the ucds socket is used to talk to multiple
agents. I have tried both setting each argument to specify the paths of
each piece (ucds socket, uinput, and virtio port) and letting Xspice set
them up automatically. Xspice by default re-creates these devices as
sockets and pipes, so it seems that Xspice is actually ideal for this
purpose; there is no need to create the devices by hand. However, any way
it's done even with the newest sources results in the same thing. In the
Fedora LXC under Ubuntu 14.04, I get a display but no agent functionality
for some reason even though the same ucds port is used by both agentd and
agent. In an Ubuntu 14.04 LXC container I can't even get X to start via the
Xspice script or a direct call to X because it segfaults when using the
spiceqxl driver.

There also appears to be no difference between letting the Xspice script
start the agents or starting the agents by hand, which isn't unexpected.

Chuck

On Tue, Nov 25, 2014 at 4:36 AM, Christophe Fergeau <cfergeau at redhat.com>
wrote:

> Hey,
>
> I'm not really familiar with Xspice, and never tried what you are trying
> to achieve, a few pointers though which you may already have found.
>
> On Sat, Nov 22, 2014 at 06:30:46AM -0600, Charles Ricketts wrote:
> > I've been surfing and source diving and now I'm all wet! I just
> > discovered LXC a couple days ago after having been a Qemu fan for years.
> > I really like the idea behind it and it seems to be far better on
> > resources! However, I wanted to get the same kind of user experience out
> > of these LXC containers as I get with Qemu+Spice. Getting Spice running
> > in the first place was a pretty simple task (once I learned my way
> > around Fedora a bit). However, I've been pounding my head against the
> > wall for almost a whole day trying to get the agent to work correctly.
> > I'm working with Xspice for this setup as it's really my only option I
> > think.
> >
> > I need a little information from you guys as I don't understand the
> > Spice protocol all too well and looking at source only gives me the gist
> > of what's going on rather than the specifics due to my lack of knowledge.
> >
> > I've tried so many things to get this working, yet nothing I try seems
> > to work. All of my work has been based around the idea that Qemu in a
> > normal Spice setup just relays information between a network socket and
> > its virtualization of a serial port. The Spice client sends to the
> > network port, and Qemu writes that to the virtual serial buffer for the
> > guest agent to read. Likewise, the agent writes to the virtual serial
> > buffer and it gets relayed through the network port by Qemu. Is this
> > correct? Also, if I'm not mistaken, Xspice is made to replace that
> > functionality: it opens a network port for a client and talks to the
> > agent(s).
> >
> > In Linux systems, a Spice VirtIO serial port gets mapped to
> > /dev/virtio-serial/com.redhat.spice.0 -> ../vport1p1. I attempted to
> > replicate this with my LXC container by using `mknod -m 600
> > /dev/vport1p1 c 181 1' (the same major/minor as the real thing).
> > However, if I'm not mistaken it doesn't *have* to be a de-facto VirtIO
> > serial port, correct? Shouldn't it work with any serial character device
> > such as /dev/ttyU0? I tried this as well and the results seemed no
> > different.
>
> Some support for Xspice was added to vdagent in the 0.15 release, see
> commit
> http://cgit.freedesktop.org/spice/linux/vd_agent/commit/?id=21175d0701a
> and the ones done around this time. In particular, a -S option to
> specify the socket to use was added at the same time as this fake uinput
> stuff.
>
> Then looking at
> http://cgit.freedesktop.org/xorg/driver/xf86-video-qxl/commit/?id=78f1115d
> it seems Xspice should be able to launch the agent automatically if it's
> at least spice-vdagent 0.15.
>
> Does that help, or have you already noticed these things but they are
> not working as expected?
>
> Christophe
>
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