[Mesa-dev] [PATCH] intel: Do temporary CPU maps of textures that are too big to GTT map.

[Eric Anholt]

This still fails, since 8192*4bpp == 32768, which is too big to use the
blitter on.

v2: Be more conservative about the size of the GTT -- I'd forgotten some
    of the horror of older hardware.
---
 src/mesa/drivers/dri/intel/intel_mipmap_tree.c |   23 +++++++++++++++++++++++
 1 file changed, 23 insertions(+)

diff --git a/src/mesa/drivers/dri/intel/intel_mipmap_tree.c b/src/mesa/drivers/dri/intel/intel_mipmap_tree.c
index ffdaec5..152d4631 100644
--- a/src/mesa/drivers/dri/intel/intel_mipmap_tree.c
+++ b/src/mesa/drivers/dri/intel/intel_mipmap_tree.c
@@ -1703,6 +1703,25 @@ intel_miptree_map_singlesample(struct intel_context *intel,
 {
    struct intel_miptree_map *map;
 
+   /* Estimate the size of the mappable aperture into the GTT.  There's an
+    * ioctl to get the whole GTT size, but not one to get the mappable subset.
+    * Generally it's 256MB, but some gen4+ (particularly things like G41)
+    * occasionally has only 128, and 830-class hardware could be either 64 or
+    * 128.  Since the kernel doesn't expose information to let us actually
+    * determine the size, just be pessimistic.
+    */
+   uint32_t gtt_size = 128 * 1024 * 1024;
+   if (intel->gen == 2)
+      gtt_size = 64 * 1024 * 1024;
+
+   /* We don't want to map two objects such that a memcpy between them would
+    * just fault one mapping in and then the other over and over forever.  So
+    * we would need to divide the GTT size by 2.  Additionally, some GTT is
+    * taken up by things like the framebuffer and the ringbuffer and such, so
+    * be more conservative.
+    */
+   uint32_t max_gtt_map_object_size = gtt_size / 4;
+
    assert(mt->num_samples <= 1);
 
    map = intel_miptree_attach_map(mt, level, slice, x, y, w, h, mode);
@@ -1749,6 +1768,10 @@ intel_miptree_map_singlesample(struct intel_context *intel,
             mt->region->tiling == I915_TILING_X &&
             mt->region->pitch < 32768) {
       intel_miptree_map_blit(intel, mt, map, level, slice);
+   } else if (mt->region->bo->size >= max_gtt_map_object_size) {
+      assert(mt->region->pitch < 32768 ||
+             mt->region->tiling == I915_TILING_NONE);
+      intel_miptree_map_blit(intel, mt, map, level, slice);
    } else {
       intel_miptree_map_gtt(intel, mt, map, level, slice);
    }
-- 
1.7.10.4