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>

1 files changed, 3 insertions, 0 deletions

diff --git a/vgasrc/vgautil.h b/vgasrc/vgautil.h
index 0f2dba4..4f37bf9 100644
--- a/vgasrc/vgautil.h
+++ b/vgasrc/vgautil.h
@@ -24,6 +24,9 @@ int cbvga_setup(void);
 // bochsdisplay.c
 int bochs_display_setup(void);
 
+// ramfb.c
+int ramfb_setup(void);
+
 // clext.c
 struct vgamode_s *clext_find_mode(int mode);
 void clext_list_modes(u16 seg, u16 *dest, u16 *last);