Module Name: src
Committed By: riastradh
Date: Wed Jul 16 21:48:53 UTC 2014
Modified Files:
src/sys/external/bsd/drm2/dist/drm/i915: i915_gem.c
Log Message:
Explain why i915_gem_release_mmap is broken.
To generate a diff of this commit:
cvs rdiff -u -r1.13 -r1.14 src/sys/external/bsd/drm2/dist/drm/i915/i915_gem.c
Please note that diffs are not public domain; they are subject to the
copyright notices on the relevant files.
Modified files:
Index: src/sys/external/bsd/drm2/dist/drm/i915/i915_gem.c
diff -u src/sys/external/bsd/drm2/dist/drm/i915/i915_gem.c:1.13 src/sys/external/bsd/drm2/dist/drm/i915/i915_gem.c:1.14
--- src/sys/external/bsd/drm2/dist/drm/i915/i915_gem.c:1.13 Wed Jul 16 20:56:24 2014
+++ src/sys/external/bsd/drm2/dist/drm/i915/i915_gem.c Wed Jul 16 21:48:53 2014
@@ -2140,6 +2140,24 @@ i915_gem_release_mmap(struct drm_i915_ge
mutex_enter(obj->base.gemo_shm_uao->vmobjlock);
KASSERT(obj->pages != NULL);
/* Force a fresh fault for each page. */
+ /*
+ * XXX OOPS! This doesn't actually do what we want.
+ * This causes a fresh fault for access to the backing
+ * pages -- but nothing accesses the backing pages
+ * directly! What is actually entered into CPU page
+ * table entries is aperture addresses which have been
+ * programmed by the GTT to refer to those backing
+ * pages.
+ *
+ * We need to clear those page table entries, but
+ * there's no good way to do that at the moment: nobody
+ * records for us a map from either uvm objects or
+ * physical device addresses to a list of all virtual
+ * pages where they have been mapped. pmap(9) records
+ * a map only from physical RAM addresses to virtual
+ * pages; it does nothing for physical device
+ * addresses.
+ */
TAILQ_FOREACH(page, &obj->igo_pageq, pageq.queue)
pmap_page_protect(page, VM_PROT_NONE);
mutex_exit(obj->base.gemo_shm_uao->vmobjlock);
