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* [Intel-gfx] [PATCH i-g-t 1/6] lib/i915_drm_local: Add I915_GEM_CREATE_EXT_FLAG_NEEDS_CPU_ACCESS
@ 2022-02-21 14:10 ` Matthew Auld
  0 siblings, 0 replies; 12+ messages in thread
From: Matthew Auld @ 2022-02-21 14:10 UTC (permalink / raw)
  To: igt-dev; +Cc: Thomas Hellström, intel-gfx

For now dump into i915_drm_local.h. Once the uapi on the kernel side is
merged, and is part of drm-next, we can sync the kernel headers and
remove this.

Signed-off-by: Matthew Auld <matthew.auld@intel.com>
Cc: Thomas Hellström <thomas.hellstrom@linux.intel.com>
---
 lib/i915/i915_drm_local.h | 27 +++++++++++++++++++++++++++
 1 file changed, 27 insertions(+)

diff --git a/lib/i915/i915_drm_local.h b/lib/i915/i915_drm_local.h
index 9e82c968..7b5285f3 100644
--- a/lib/i915/i915_drm_local.h
+++ b/lib/i915/i915_drm_local.h
@@ -21,6 +21,33 @@ extern "C" {
  */
 #define I915_ENGINE_CLASS_COMPUTE 4
 
+/*
+ * Signal to the kernel that the object will need to be accessed via
+ * the CPU.
+ *
+ * Only valid when placing objects in I915_MEMORY_CLASS_DEVICE, and only
+ * strictly required on platforms where only some of the device memory
+ * is directly visible or mappable through the CPU, like on DG2+.
+ *
+ * One of the placements MUST also be I915_MEMORY_CLASS_SYSTEM, to
+ * ensure we can always spill the allocation to system memory, if we
+ * can't place the object in the mappable part of
+ * I915_MEMORY_CLASS_DEVICE.
+ *
+ * Note that buffers that need to be captured with EXEC_OBJECT_CAPTURE,
+ * will need to enable this hint, if the object can also be placed in
+ * I915_MEMORY_CLASS_DEVICE, starting from DG2+. The execbuf call will
+ * throw an error otherwise. This also means that such objects will need
+ * I915_MEMORY_CLASS_SYSTEM set as a possible placement.
+ *
+ * Without this hint, the kernel will assume that non-mappable
+ * I915_MEMORY_CLASS_DEVICE is preferred for this object. Note that the
+ * kernel can still migrate the object to the mappable part, as a last
+ * resort, if userspace ever CPU faults this object, but this might be
+ * expensive, and so ideally should be avoided.
+ */
+#define I915_GEM_CREATE_EXT_FLAG_NEEDS_CPU_ACCESS (1 << 0)
+
 #if defined(__cplusplus)
 }
 #endif
-- 
2.34.1


^ permalink raw reply related	[flat|nested] 12+ messages in thread

end of thread, other threads:[~2022-02-21 14:13 UTC | newest]

Thread overview: 12+ messages (download: mbox.gz / follow: Atom feed)
-- links below jump to the message on this page --
2022-02-21 14:10 [Intel-gfx] [PATCH i-g-t 1/6] lib/i915_drm_local: Add I915_GEM_CREATE_EXT_FLAG_NEEDS_CPU_ACCESS Matthew Auld
2022-02-21 14:10 ` [igt-dev] " Matthew Auld
2022-02-21 14:10 ` [Intel-gfx] [PATCH i-g-t 2/6] lib/i915: wire up optional flags for gem_create_ext Matthew Auld
2022-02-21 14:10   ` [igt-dev] " Matthew Auld
2022-02-21 14:10 ` [Intel-gfx] [PATCH i-g-t 3/6] tests/i915/gem_create: test NEEDS_CPU_ACCESS Matthew Auld
2022-02-21 14:10   ` [igt-dev] " Matthew Auld
2022-02-21 14:10 ` [Intel-gfx] [PATCH i-g-t 4/6] lib/i915: add gem_create_with_cpu_access_in_memory_regions Matthew Auld
2022-02-21 14:10   ` [igt-dev] " Matthew Auld
2022-02-21 14:10 ` [Intel-gfx] [PATCH i-g-t 5/6] i915/tests/capture: add a negative test for NEEDS_CPU_ACCESS Matthew Auld
2022-02-21 14:10   ` [igt-dev] " Matthew Auld
2022-02-21 14:10 ` [Intel-gfx] [PATCH i-g-t 6/6] lib/i915: request CPU_ACCESS for fb objects Matthew Auld
2022-02-21 14:10   ` [igt-dev] " Matthew Auld

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