Documentation/gpu/rfc/i915_small_bar.h

Source file repositories/reference/linux-study-clean/Documentation/gpu/rfc/i915_small_bar.h

File Facts

System
Linux kernel
Corpus path
Documentation/gpu/rfc/i915_small_bar.h
Extension
.h
Size
7233 bytes
Lines
190
Domain
Support Tooling And Documentation
Bucket
Documentation
Inferred role
Support Tooling And Documentation: implementation source
Status
source implementation candidate

Why This File Exists

Repository support layer: documentation, build tooling, samples, user-space helper tools, generated initramfs support, licenses, and validation utilities.

Dependency Surface

Detected Declarations

Annotated Snippet

struct __drm_i915_memory_region_info {
	/** @region: The class:instance pair encoding */
	struct drm_i915_gem_memory_class_instance region;

	/** @rsvd0: MBZ */
	__u32 rsvd0;

	/**
	 * @probed_size: Memory probed by the driver
	 *
	 * Note that it should not be possible to ever encounter a zero value
	 * here, also note that no current region type will ever return -1 here.
	 * Although for future region types, this might be a possibility. The
	 * same applies to the other size fields.
	 */
	__u64 probed_size;

	/**
	 * @unallocated_size: Estimate of memory remaining
	 *
	 * Requires CAP_PERFMON or CAP_SYS_ADMIN to get reliable accounting.
	 * Without this (or if this is an older kernel) the value here will
	 * always equal the @probed_size. Note this is only currently tracked
	 * for I915_MEMORY_CLASS_DEVICE regions (for other types the value here
	 * will always equal the @probed_size).
	 */
	__u64 unallocated_size;

	union {
		/** @rsvd1: MBZ */
		__u64 rsvd1[8];
		struct {
			/**
			 * @probed_cpu_visible_size: Memory probed by the driver
			 * that is CPU accessible.
			 *
			 * This will be always be <= @probed_size, and the
			 * remainder (if there is any) will not be CPU
			 * accessible.
			 *
			 * On systems without small BAR, the @probed_size will
			 * always equal the @probed_cpu_visible_size, since all
			 * of it will be CPU accessible.
			 *
			 * Note this is only tracked for
			 * I915_MEMORY_CLASS_DEVICE regions (for other types the
			 * value here will always equal the @probed_size).
			 *
			 * Note that if the value returned here is zero, then
			 * this must be an old kernel which lacks the relevant
			 * small-bar uAPI support (including
			 * I915_GEM_CREATE_EXT_FLAG_NEEDS_CPU_ACCESS), but on
			 * such systems we should never actually end up with a
			 * small BAR configuration, assuming we are able to load
			 * the kernel module. Hence it should be safe to treat
			 * this the same as when @probed_cpu_visible_size ==
			 * @probed_size.
			 */
			__u64 probed_cpu_visible_size;

			/**
			 * @unallocated_cpu_visible_size: Estimate of CPU
			 * visible memory remaining
			 *
			 * Note this is only tracked for
			 * I915_MEMORY_CLASS_DEVICE regions (for other types the
			 * value here will always equal the
			 * @probed_cpu_visible_size).
			 *
			 * Requires CAP_PERFMON or CAP_SYS_ADMIN to get reliable
			 * accounting.  Without this the value here will always
			 * equal the @probed_cpu_visible_size. Note this is only
			 * currently tracked for I915_MEMORY_CLASS_DEVICE
			 * regions (for other types the value here will also
			 * always equal the @probed_cpu_visible_size).
			 *
			 * If this is an older kernel the value here will be
			 * zero, see also @probed_cpu_visible_size.
			 */
			__u64 unallocated_cpu_visible_size;
		};
	};
};

/**
 * struct __drm_i915_gem_create_ext - Existing gem_create behaviour, with added
 * extension support using struct i915_user_extension.
 *
 * Note that new buffer flags should be added here, at least for the stuff that
 * is immutable. Previously we would have two ioctls, one to create the object

Annotation

Implementation Notes