[Spice-devel] Implementing channel between module at spice client and guest OS

[Marc-André Lureau]

Hi

----- Original Message -----
> > -chardev spiceport,id=spiceportfoobar,name=com.foobar -device
> > virtserialport,bus=virtio-serial0.0,nr=2,chardev=spiceportfoobar,id=channel1,name=com.foobar
> 
> Just to make sure, this will create serial device at
> /dev/virtio-ports/com.foobar, right?

yes

> > > At client side I would like to implement a component that interact with
> > > this myappl port, I could not find a way to load shared library or
> > > similar
> > > dynamic module into client in spicy usage.
> > >
> > 
> > At client side, you can follow spicy.c example. In channel_new(), you
> > want to connect to the port channel signals. When
> > "notify::port-opened", you can decide to handle that channel  based on
> > its "port-name".
> 
> Which is spiceportfoobar in above example, right?

No, this is qemu device name. The port name is "com.foobar" (spiceport,..name=)

> And I use spice_port_write_async/spice_port_event to manage this channel,
> right?

Yes, check spicy.c example code.

> > 
> > > If dynamic loading of modules is possible, is there any example of how to
> > > do so?
> > >
> > > If dynamic loading of modules is impossible, is there a plan to allow it?
> > 
> > There is currently no registry of channel or port handlers to be
> > loaded dynamically. There is currently no plan to add it, but that
> > could be added later.
> 
> Is there a reason against of having something dynamic?

No, it's just not needed so far.

> I mean if such support will be submitted will it be rejected?

No, this use case is perfectly valid. Just make sure to propose a generic solution.

> 
> > 
> > > Assuming there is the option to load a module.
> > >
> > > I could not find in vdi spec[1] description of the vdi_port interface and
> > > what should I do in order to communicate with the guest.
> > >
> > > Provided this is possible somehow, as it is working for vd_agent... and
> > > provided external modules can be loaded.
> > >
> > > I can guess that each 'name' in the above example myapp can be connected
> > > by
> > > different implementation, is that right?
> > >
> > > Assuming we have channel between module running on client machine and the
> > > agent running on guest machine using virtual serial, is there support for
> > > transferring RS232 controls? Such as DTR/DSR to detect if the device is
> > > opened at guest side and if device is opened at client side? And detect
> > > disconnection?
> > 
> > 
> > You can also redirect a serial device from qemu:
> > 
> > -chardev spiceport,id=spiceportfoobar,name=org.spice.spicy -serial
> > chardev:spiceportfoobar
> > 
> > (with kernel argument "console=tty0 console=ttyS0,115200n8")
> 
> Here I lost you... I do not need the 'console'... I need a channel of
> following:
> 
> module -> client ----spice-protocol----> qemu --> guest --> application
> 
> so that:
> 
> module <---------------------stream-----------------------> application
> 
> My questions now are:
> 1. how application know if there is module on the other side?
> 2. how module knows if there is application on the other side?
> 
> Had this standard RS-232 I could use DTR/DSR... but maybe it is a better
> way... or none.

I think you should be able to use the port event for that. But you'll have to do some reasearch, this is new territory :)