[Spice-devel] Add support for A8 bitmap format

[Alon Levy]

On Sat, Jun 16, 2012 at 01:57:49AM -0400, Yaniv Kaul wrote:
> ----- Original Message -----
> > Hello,
> > 
> > The following patches add support for a new A8 bitmap format, and for
> > LZ compression of it. This format is heavliy used by the X server
> > Render extension for glyphs and geometry information.
> > 
> > I have verified that the patches with an experiemental version of the
> > QXL X driver that can generate such pixmaps in the video memory of
> > the
> > QXL device.
> > 
> > Thanks,
> > Soren
> 
> - I'm not sure I understand how'll it work with older clients (need feature negotiation, but from guest driver to server and from server to client?). The driver would have to follow whatever the client that is connected to it can work with? I guess we need to solve the general problem of how a new feature in the driver that affects the client should be handled, this is a private case of it.
> Y.
> 

Perhaps this is really required in this case. We could do something like
the following:

Device memory: add client_capabilities == SPICE_DISPALY_CAP_*
Device added INTERRUPT_CLIENT_CAPS_UPDATED
Server QXLInterface->update_client_capabilities
Server & Client SPICE_DISPLAY_CAP_A8

Only problem with this approach is that the driver doesn't have an
interrupt handler, and it won't until we move to KMS.

Heavy handed alternative:
 - Filter the messages in the server and translate any A8 message to ??
 - Don't allow clients to connect without CAP_A8 if server advertises
   it, & advertise it iff some magic qemu command line, i.e. -device
   qxl,use_a8=1 . Driver will see the same parameter.

I guess I'm advocating the last option - for older client support we run
without use_a8=1, also for windows guests. For better performing new
xf86 driver we use use_a8=1 and require new clients as a result.

> > 
> > 
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