virtio_pci: add an option to disable legacy driver

Useful for testing device virtio 1 compatibility.
Based on patch by Rusty - couldn't resist putting
that flying car joke in there!

Signed-off-by: Michael S. Tsirkin <mst@redhat.com>
Signed-off-by: Rusty Russell <rusty@rustcorp.com.au>

1 files changed, 19 insertions, 0 deletions

diff --git a/drivers/virtio/Kconfig b/drivers/virtio/Kconfig
index 083fb45950f5..b546da5d8ea3 100644
--- a/drivers/virtio/Kconfig
+++ b/drivers/virtio/Kconfig
@@ -19,6 +19,25 @@ config VIRTIO_PCI
 
           If unsure, say M.
 
+config VIRTIO_PCI_LEGACY
+        bool "Support for legacy virtio draft 0.9.X and older devices"
+        default y
+        depends on VIRTIO_PCI
+        ---help---
+          Virtio PCI Card 0.9.X Draft (circa 2014) and older device support.
+
+          This option enables building a transitional driver, supporting
+          both devices conforming to Virtio 1 specification, and legacy devices.
+          If disabled, you get a slightly smaller, non-transitional driver,
+          with no legacy compatibility.
+
+          So look out into your driveway.  Do you have a flying car?  If
+          so, you can happily disable this option and virtio will not
+          break.  Otherwise, leave it set.  Unless you're testing what
+          life will be like in The Future.
+
+          If unsure, say Y.
+
 config VIRTIO_BALLOON
         tristate "Virtio balloon driver"
         depends on VIRTIO