#include <i915_drm.h>

Collaboration diagram for drm_i915_gem_create_ext_memory_regions:

Public Attributes
struct i915_user_extension	base

__u32	pad

__u32	num_regions

__u64	regions

Detailed Description

struct drm_i915_gem_create_ext_memory_regions - The I915_GEM_CREATE_EXT_MEMORY_REGIONS extension.

Set the object with the desired set of placements/regions in priority order. Each entry must be unique and supported by the device.

This is provided as an array of struct drm_i915_gem_memory_class_instance, or an equivalent layout of class:instance pair encodings. See struct drm_i915_query_memory_regions and DRM_I915_QUERY_MEMORY_REGIONS for how to query the supported regions for a device.

As an example, on discrete devices, if we wish to set the placement as device local-memory we can do something like:

.. code-block:: C

struct drm_i915_gem_memory_class_instance region_lmem = { .memory_class = I915_MEMORY_CLASS_DEVICE, .memory_instance = 0, }; struct drm_i915_gem_create_ext_memory_regions regions = { .base = { .name = I915_GEM_CREATE_EXT_MEMORY_REGIONS }, .regions = (uintptr_t)&region_lmem, .num_regions = 1, }; struct drm_i915_gem_create_ext create_ext = { .size = 16 * PAGE_SIZE, .extensions = (uintptr_t)&regions, };

int err = ioctl(fd, DRM_IOCTL_I915_GEM_CREATE_EXT, &create_ext); if (err) ...

At which point we get the object handle in &drm_i915_gem_create_ext.handle, along with the final object size in &drm_i915_gem_create_ext.size, which should account for any rounding up, if required.

Note that userspace has no means of knowing the current backing region for objects where @num_regions is larger than one. The kernel will only ensure that the priority order of the @regions array is honoured, either when initially placing the object, or when moving memory around due to memory pressure

On Flat-CCS capable HW, compression is supported for the objects residing in I915_MEMORY_CLASS_DEVICE. When such objects (compressed) have other memory class in @regions and migrated (by i915, due to memory constraints) to the non I915_MEMORY_CLASS_DEVICE region, then i915 needs to decompress the content. But i915 doesn't have the required information to decompress the userspace compressed objects.

So i915 supports Flat-CCS, on the objects which can reside only on I915_MEMORY_CLASS_DEVICE regions.

Member Data Documentation

◆ base

struct i915_user_extension drm_i915_gem_create_ext_memory_regions::base

@base: Extension link. See struct i915_user_extension.

◆ num_regions

__u32 drm_i915_gem_create_ext_memory_regions::num_regions

@num_regions: Number of elements in the @regions array.

◆ pad

__u32 drm_i915_gem_create_ext_memory_regions::pad

@pad: MBZ

◆ regions

__u64 drm_i915_gem_create_ext_memory_regions::regions

@regions: The regions/placements array.

An array of struct drm_i915_gem_memory_class_instance.

The documentation for this struct was generated from the following file: