[libvirt] ivshmem server

[Andrew Jones]

Cam,

ping

Please let us know your opinion on integrating ivshmem-server
into libvirt. Also, please confirm the licensing would allow it.

Thanks,
Drew

----- Original Message -----
> 
> 
> ----- Original Message -----
> > On Tue, Nov 20, 2012 at 01:16:56PM -0500, Andrew Jones wrote:
> > > 
> > > This mail is meant to get a discussion started. Please keep me on
> > > cc
> > > for the discussion, as I'm not subscribed to libvir-list.
> > > 
> > > ivshmem is an implementation of an inter-VM communication
> > > channel.
> > > Support for this has been in qemu since v0.14.0 and libvirt
> > > patches
> > > have been recently posted[1]. What's still missing is the ivshmem
> > > server. The ivshmem server is needed when one would like to use
> > > interrupts with ivshmem. The server manages a set of eventfds
> > > to send/recv those interrupts. There is currently only one
> > > implementation of this server that I'm aware of, which is
> > > available
> > > from this git repo [2] in the ivshmem-server directory. My
> > > suggestion
> > > for libvirt is that this code be integrated into libvirt, rather
> > > than managed by libvirt, for the following reasons
> > > 
> > > 1. libvirt should keep track of the socket path in order to build
> > >    ivshmem's command line anyway.
> > > 2. the current ivshmem server code is ~300 lines, so it shouldn't
> > > be
> > >    a large integration effort.
> > > 3. keeping ivhsmem server separate increases the package
> > > management
> > >    that distributions need to do. afaik, it isn't currently
> > >    packaged
> > >    for any distribution.
> > > 
> > > One concern I have with the git repo [2] is that I don't see any
> > > license for ivshmem-server. I've cc'ed Cam for his input.
> > 
> > I guess my main question would be how much more, if any, is the
> > ivshmem-server expected to grow over time ? I wouldn't want to
> > get into a fork-situation if people are planning to do much more
> > dev work on the current ivshmem-server code.
> 
> Here's the entire git log for ivshmem-server
> 
> Date:   Thu Sep 6 11:36:33 2012 -0600
>     Error clean-up
>     Fixed a warning and cleaned up two error message
> Date:   Tue Nov 16 11:11:16 2010 -0700
>     just a few fixups
> Date:   Tue Jun 15 14:43:01 2010 -0600
>     Adding the ivshmem server here - Cam
> 
> So there was an initial drop, then nothing for two years, and then
> some recent cleanups. I believe that it serves a simple enough
> purpose that there shouldn't be any more growth.
> 
> > 
> > NB, if the code is integrated into libvirt, I think it would
> > still have to run in a separate daemon. The reason is that we
> > want to ensure that guests remain fully functional, even when
> > libvirtd is stopped (whether for RPM upgrade, or due to crash)
> > 
> > I've no particular strong opinion either way on your proposal.
> > On the surface it seems reasonable to me.
> > 
> > Daniel
> > --
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> > 
>