qemu: add qemu ramfb support

Add support for qemu ramfb.  This is a simple boot framebuffer device,
with normal ram being used to back the framebuffer and fw_cfg being used
to configure the device.

Use case (on x86): boot display for vgpu devices (which neither emulate
vga nor have a vgabios).

Sharing fw_cfg code with seabios turned out to be difficuilt due to
various dependencies the code has on infrastructure which only seabios
has.  So include a copy of the code here, with those dependencies
removed and also stripped down because we don't need a non-dma fallback
here.

Signed-off-by: Gerd Hoffmann <kraxel@redhat.com>
(cherry picked from commit d9a8b867a3af8090290b69b8f94b24e7fba9e504)
5 files changed
tree: 9c21c5021406ac12f9035f99c36c0aeb332a69ed
  1. .gitignore
  2. COPYING
  3. COPYING.LESSER
  4. Makefile
  5. README
  6. docs/
  7. scripts/
  8. src/
  9. vgasrc/