[PATCH] drm/nouveau: add kconfig option to turn off nouveau legacy contexts.

[Dave Airlie]

From: Dave Airlie <airlied at redhat.com>

There was a nouveau DDX that relied on legacy context ioctls to work,
but we fixed it years ago, give distros that have a modern DDX the
option to break the uAPI and close the mess of holes that legacy
context support is.

Signed-off-by: Dave Airlie <airlied at redhat.com>
---
 drivers/gpu/drm/nouveau/Kconfig       | 10 ++++++++++
 drivers/gpu/drm/nouveau/nouveau_drm.c |  7 +++++--
 2 files changed, 15 insertions(+), 2 deletions(-)

diff --git a/drivers/gpu/drm/nouveau/Kconfig b/drivers/gpu/drm/nouveau/Kconfig
index 00cd9ab8948d..688b6f618b65 100644
--- a/drivers/gpu/drm/nouveau/Kconfig
+++ b/drivers/gpu/drm/nouveau/Kconfig
@@ -21,6 +21,16 @@ config DRM_NOUVEAU
 	help
 	  Choose this option for open-source NVIDIA support.
 
+config NOUVEAU_LEGACY_CTX_SUPPORT
+	bool "Nouveau legacy context support"
+	default y
+	help
+	  There was a version of the nouveau DDX that relied on legacy
+	  ctx ioctls not erroring out. But that was back in time a long
+	  ways, so offer a way to disable it now. For uapi compat with
+	  old nouveau ddx this should be on by default, but modern distros
+	  should consider turning it off.
+
 config NOUVEAU_PLATFORM_DRIVER
 	bool "Nouveau (NVIDIA) SoC GPUs"
 	depends on DRM_NOUVEAU && ARCH_TEGRA
diff --git a/drivers/gpu/drm/nouveau/nouveau_drm.c b/drivers/gpu/drm/nouveau/nouveau_drm.c
index 5020265bfbd9..6ab9033f49da 100644
--- a/drivers/gpu/drm/nouveau/nouveau_drm.c
+++ b/drivers/gpu/drm/nouveau/nouveau_drm.c
@@ -1094,8 +1094,11 @@ nouveau_driver_fops = {
 static struct drm_driver
 driver_stub = {
 	.driver_features =
-		DRIVER_GEM | DRIVER_MODESET | DRIVER_PRIME | DRIVER_RENDER |
-		DRIVER_KMS_LEGACY_CONTEXT,
+		DRIVER_GEM | DRIVER_MODESET | DRIVER_PRIME | DRIVER_RENDER
+#if defined(CONFIG_NOUVEAU_LEGACY_CTX_SUPPORT)
+		| DRIVER_KMS_LEGACY_CONTEXT
+#endif
+		,
 
 	.open = nouveau_drm_open,
 	.postclose = nouveau_drm_postclose,
-- 
2.20.1