Adds a "ram" attribute globally to the video.model element, that changes
the resulting qemu command line only if video.type == "qxl".
<video>
<model type='qxl' ram='65536' vram='65536' heads='1'/>
</video>
That attribute gets a default value of 64*1024. The schema is unchanged
for other video element types.
The resulting qemu command line change is the addition of
-global qxl-vga.ram_size=<ram>*1024
or
-global qxl.ram_size=<ram>*1024
For the main and secondary qxl devices respectively.
The default for the qxl ram bar is 64*1024 kilobytes (the same as the
default qxl vram bar size).
For qemu names the primary vga as "qxl-vga":
1) if vram is specified for 2nd qxl device:
-vga qxl -global qxl-vga.vram_size=$SIZE \
-device qxl,id=video1,vram_size=$SIZE,...
2) if vram is not specified for 2nd qxl device, (use the default
set by global):
-vga qxl -global qxl-vga.vram_size=$SIZE \
-device qxl,id=video1,...
For qemu names all qxl devices as "qxl":
1) if vram is specified for 2nd qxl device:
-vga qxl -global qxl.vram_size=$SIZE \
-device qxl,id=video1,vram_size=$SIZE ...
2) if vram is not specified for 2nd qxl device:
-vga qxl -global qxl-vga.vram_size=$SIZE \
-device qxl,id=video1,...
"-global" is the only way to define vram_size for the primary qxl
device, regardless of how qemu names it, (It's not good a good
way, as original idea of "-global" is to set a global default for
a driver property, but to specify vram for first qxl device, we
have to use it).
For other qxl devices, as they are represented by "-device", could
specify it directly and seperately for each, and it overrides the
default set by "-global" if specified.
v1 - v2:
* modify "virDomainVideoDefaultRAM" so that it returns 16M as the
default vram_size for qxl device.
* vram_size * 1024 (qemu accepts bytes for vram_size).
* apply default vram_size for qxl device for which vram_size is
not specified.
* modify "graphics-spice" tests (more sensiable vram_size)
* Add an argument of virDomainDefPtr type for qemuBuildVideoDevStr,
to use virDomainVideoDefaultRAM in qemuBuildVideoDevStr).
v2 - v3:
* Modify default video memory size for qxl device from 16M to 24M
* Update codes to be consistent with changes on qemu_capabilities.*
