[Spice-devel] Spice agent and LXC

[Charles Ricketts]

Well, I have Spice working perfectly fine in a Windows install. However,
seeing as that's not pertinent to the Linux side of things I went ahead
and installed Ubuntu 14.04 in Qemu and, as expected, everything worked.
I didn't bother with the git sources in this install, because I was 99%
sure it was going to work anyway. I don't have a Fedora ISO lying around
to test it with, but I imagine that the results would be the same.

However, I don't think that even this is pertinent to the problem. The
reason I think this is because Qemu acts as the Spice server if I am
correct. Qemu relays information from a network socket assigned on the
command line to the virtualized serial port and vice versa. Since an LXC
installation is sans-Qemu server then I must use Xspice in order to take
the place of Qemu and act as a Spice server in order to relay
information between the agents/QXL driver and the Spice client. So,
testing it within Qemu doesn't really reflect the problem at all. Beyond
Qemu, there's really no way to test it sans-LXC. Actually, now that I
think about it I may be able to run Xspice directly within a VM and then
attempt to connect to it... I'll try that out later on and let you know
how/if that works out. I may have to get that Fedora ISO after all just
to broaden the test cases.

I realize that I'm effectively attempting to use Spice outside of normal
circumstances. However, the way that Xspice behaves -- such as creating
its own versions of the virtio port (as a socket rather than a character
device) and uinput (as a pipe) and attempting to destroy any existing
versions of those files -- leads me to believe that Xspice was almost
built for the purpose even if not intentionally. And, as I had said
before, I got it mostly working in a Fedora LXC container (only lacking
client functionality, which is why I asked for input in the first place ;).

I would like to be able to provide a stack trace of the segfault I get
in the Ubuntu LXC, but I'm unsure how to compile the sources with
debugging symbols. Any help in that respect?

On 11/27/2014 03:50 AM, Christophe Fergeau wrote:
> On Wed, Nov 26, 2014 at 05:16:52PM -0600, Charles Ricketts wrote:
>> 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.
>>
> Have you tried all of this without lxc to see how well/bad it works
> without adding lxc to the mix?
>
> Christophe