Improvement: only start the refresh once the memory is mmap'ed first; so, if we boot the system only to console and dont start X, the refresh does not kick in.
Also, added shutdown pre sync defensively, as this is also done similarly in other drivers.

virtio_gpu: add support for xf86-video-scfb

Hi. Sorry for not being too active on this - just wanted to give a heads-up that I am looking at disabling the functionality by default as asked by @imp; currently I am "under water" with lots of things to do at work and with family, and therefore having difficulties to find time to look at this; however this is not forgotten, and I will come back asap. Thanks!

In D55012#1261935, @andrew wrote:

What is the overhead form all the extra wakeups this adds? I'd prefer we add a way for userspace to tell the kernel to perform an update.

Sorry, new here... still learning
This patch has -U9999, as requested

Updated code according to review comments:

• removed vtgpu_initialized flag
• flush task only started when /dev/fd0 is available
• improved logic for device_printf when attached
• removed unnecessary if conditions