On Tue, Dec 22, 2015 at 11:50:47AM +0530, ankitprasad.r.sharma@xxxxxxxxx wrote:
> @@ -456,6 +457,21 @@ struct drm_i915_gem_create {
> */
> __u32 handle;
> __u32 pad;
> + /**
> + * Requested flags (currently used for placement
> + * (which memory domain))
> + *
> + * You can request that the object be created from special memory
> + * rather than regular system pages using this parameter. Such
> + * irregular objects may have certain restrictions (such as CPU
> + * access to a stolen object is verboten).
> + *
> + * This can be used in the future for other purposes too
> + * e.g. specifying tiling/caching/madvise
> + */
> + __u64 flags;
We've just been discussing future flags, and it seems like we want to
reserve the first 8 bits as a placement enum.
#define I915_CREATE_PLACEMENT_NORMAL 0 /* standard swappable bo */
#define I915_CREATE_PLACEMENT_STOLEN 1 /* Cannot use CPU mmaps */
/*
#define I915_CREATE_PLACEMENT_PRIVATE_ACTIVE 2 /* From the file private freed pool */
#define I915_CREATE_PLACEMENT_PRIVATE_INACTIVE 3 /* From the file private freed pool */
*/
#define I915_CREATE_PLACEMENT_MASK 0xff
#define __I915_CREATE_UNKNOWN_FLAGS ~I915_CREATE_PLACEMENT_MASK
So thinking ahead, rearranging this
> /* Allocate the new object */
> - obj = i915_gem_alloc_object(dev, size);
> + if (flags & I915_CREATE_PLACEMENT_STOLEN) {
> + mutex_lock(&dev->struct_mutex);
> + obj = i915_gem_object_create_stolen(dev, size);
> + if (!obj) {
> + mutex_unlock(&dev->struct_mutex);
> + return -ENOMEM;
> + }
> +
> + /* Always clear fresh buffers before handing to userspace */
> + ret = i915_gem_object_clear(obj);
> + if (ret) {
> + drm_gem_object_unreference(&obj->base);
> + mutex_unlock(&dev->struct_mutex);
> + return ret;
> + }
> +
> + mutex_unlock(&dev->struct_mutex);
> + } else {
> + obj = i915_gem_alloc_object(dev, size);
> + }
as something like:
u32 placement = flags & I915_CREATE_PLACEMENT_MASK;
switch (placement) {
/*
case I915_CREATE_PLACEMENT_PRIVATE_ACTIVE:
case I915_CREATE_PLACEMENT_PRIVATE_INACTIVE:
use_private_pool = true;
obj = alloc_from_pool(file, size, placement == ACTIVE);
if (obj != NULL)
break;
/* fallthrough */
*/
case I915_CREATE_PLACEMENT_NORMAL:
obj = i915_gem_alloc_object(dev, size);
break;
case I915_CREATE_PLACEMENT_STOLEN:
obj = alloc_from_stolen(dev, size);
break;
}
would ease my future plans and look a bit neater :)
-Chris
--
Chris Wilson, Intel Open Source Technology Centre
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