Re: [Qemu-devel] Spice project is now open

[Anthony Liguori <anthony@codemonkey.ws>]

Izik Eidus wrote:
> I should speek with the marketing guys, will be able to answer on that
> specific question in few days.
>
>
> But simple 2D Commands are just not enougth for spice.
> We have multiple drawing surfaces, that are depended on each other.
> We Dont renender untill the very moment that the guest try to read its
> video memory, we have video streaming, and we have cache based by the
> guest driver.
> We have private channels for stuff like keyboard, display and so on...
>   

The video streaming is an encoding heuristic though, right?

The lack of guest visible rendering is interesting.

  

>> I'm not familiar with what a "depth viewing tree".  Can you elaborate?
>>     
>
> In it simplest way of working, we will take the simplest case of what
> it is doing:
> If you have application that rendered a window, and then it renendered
> another window on top of it, you dont want to send the commands that
> rendered the old window, beacuse the new commands hide the older one...
>   

Ah, this is unique to a windowing protocol.  A framebuffer protocol does 
not have to worry about this because the OS does it for you.

How well does this work with a Linux guest?  To get a lot of this level 
of information, you have to hook in at the X protocol level (which is 
what NX does).  Can you really do much at the X driver level?

Of course, a lot of interesting stuff (like drawing ops and text 
rendering) doesn't even happen in the X server these days.

>>> I think we should allow freedom of choice to the users to decide
>>> what protcol they want to use, Spice and VNC are all diffrent and
>>> were born to meet diffrent goals.
>>>   
>>>       
>> What would be ideal, is if there was a mechanism whereas a client
>> could connect to the VNC server, and get VNC traffic if it's a normal
>> VNC client, but if it was a smarter client, got a more sophisticated 
>> stream.  If that was something that was Spice or Spice-like, that
>> would be perfect.
>>
>> But to introduce another protocol where a user has to make a choice
>> to use Spice over VNC, I think we need a really good justification
>> for that.  It's really about complexity.  A user shouldn't have to
>> know about Spice or VNC.  They shouldn't have to contemplate the
>> trade-offs of whether their management tool is aware or not.  It
>> should Just Work.
>>     
>
>
> This why we suggest the VDI interface, to solve all this choicses we
> made for the users,
>   

Okay, but it's hard to evaluate that suggestion without seeing the VDI 
interface :-)

> Think about qemu give infastracture to multiple librarys to use it?
> For example one user can use qemu with  VNC, one with SPICE, and one
> can use qemu with diffrent private local rendering soultion (for highly
> fast local 3d rendering...)
>   

As I said, I don't have a problem with externalizing things.  I think 
there's some discussion about how best to do that.  For instance, I 
think we want to avoid shared library plugins as it introduces a good 
deal of instability into our address space.

Regards,

Anthony Liguori