diff options
Diffstat (limited to 'include/uapi/drm/i915_drm.h')
| -rw-r--r-- | include/uapi/drm/i915_drm.h | 22 |
1 files changed, 22 insertions, 0 deletions
diff --git a/include/uapi/drm/i915_drm.h b/include/uapi/drm/i915_drm.h index aa2d4c73a97d..1c69ed16a923 100644 --- a/include/uapi/drm/i915_drm.h +++ b/include/uapi/drm/i915_drm.h @@ -63,6 +63,28 @@ extern "C" { #define I915_RESET_UEVENT "RESET" /* + * i915_user_extension: Base class for defining a chain of extensions + * + * Many interfaces need to grow over time. In most cases we can simply + * extend the struct and have userspace pass in more data. Another option, + * as demonstrated by Vulkan's approach to providing extensions for forward + * and backward compatibility, is to use a list of optional structs to + * provide those extra details. + * + * The key advantage to using an extension chain is that it allows us to + * redefine the interface more easily than an ever growing struct of + * increasing complexity, and for large parts of that interface to be + * entirely optional. The downside is more pointer chasing; chasing across + * the __user boundary with pointers encapsulated inside u64. + */ +struct i915_user_extension { + __u64 next_extension; + __u32 name; + __u32 flags; /* All undefined bits must be zero. */ + __u32 rsvd[4]; /* Reserved for future use; must be zero. */ +}; + +/* * MOCS indexes used for GPU surfaces, defining the cacheability of the * surface data and the coherency for this data wrt. CPU vs. GPU accesses. */ |