sample: vfio bochs vbe display (host device for bochs-drm)

Display device, demo-ing the vfio dmabuf display interface
(VFIO_GFX_PLANE_TYPE_DMABUF).  Compatible enough to qemu stdvga
that bochs-drm.ko can be used as guest driver.

Signed-off-by: Gerd Hoffmann <kraxel@redhat.com>
Signed-off-by: Alex Williamson <alex.williamson@redhat.com>

samples/Kconfig

@@ -132,6 +132,19 @@ config SAMPLE_VFIO_MDEV_MDPY_FB
 	help
 	  Guest fbdev driver for the virtual display sample driver.
 
+config SAMPLE_VFIO_MDEV_MBOCHS
+	tristate "Build VFIO mdpy example mediated device sample code -- loadable modules only"
+	depends on VFIO_MDEV_DEVICE && m
+	help
+	  Build a virtual display sample driver for use as a VFIO
+	  mediated device.  It supports the region display interface
+	  (VFIO_GFX_PLANE_TYPE_DMABUF).
+	  Emulate enough of qemu stdvga to make bochs-drm.ko happy.
+	  That is basically the vram memory bar and the bochs dispi
+	  interface vbe registers in the mmio register bar.
+	  Specifically it does *not* include any legacy vga stuff.
+	  Device looks a lot like "qemu -device secondary-vga".
+
 config SAMPLE_STATX
 	bool "Build example extended-stat using code"
 	depends on BROKEN

samples/vfio-mdev/Makefile

@@ -1,3 +1,4 @@
 obj-$(CONFIG_SAMPLE_VFIO_MDEV_MTTY) += mtty.o
 obj-$(CONFIG_SAMPLE_VFIO_MDEV_MDPY) += mdpy.o
 obj-$(CONFIG_SAMPLE_VFIO_MDEV_MDPY_FB) += mdpy-fb.o
+obj-$(CONFIG_SAMPLE_VFIO_MDEV_MBOCHS) += mbochs.o