From c890e2d5313e8e8f4fb54258dc2bbb2c7dd901ce Mon Sep 17 00:00:00 2001 From: Chris Wilson Date: Fri, 18 Mar 2016 10:42:59 +0200 Subject: [PATCH] drm/i915: Codify our assumption that the Global GTT is <= 4GiB MIME-Version: 1.0 Content-Type: text/plain; charset=utf8 Content-Transfer-Encoding: 8bit Throughout the code base, we use u32 for offsets into the global GTT. If we ever see any hardware with a larger GGTT, then we run the real risk of silent corruption. So test for our assumption up front so that we have a nice reminder should the time come when it fails. Signed-off-by: Chris Wilson Cc: Ville Syrjälä Cc: Daniel Vetter Signed-off-by: Joonas Lahtinen [Rebased and changed 1ull -> 1ULL, cut 80 char line] Reviewed-by: Tvrtko Ursulin Reviewed-by: Mika Kuoppala Link: http://patchwork.freedesktop.org/patch/msgid/1458290579-27783-1-git-send-email-joonas.lahtinen@linux.intel.com --- drivers/gpu/drm/i915/i915_gem_gtt.c | 8 ++++++++ 1 file changed, 8 insertions(+) diff --git a/drivers/gpu/drm/i915/i915_gem_gtt.c b/drivers/gpu/drm/i915/i915_gem_gtt.c index 799576e13f65..0715bb74d306 100644 --- a/drivers/gpu/drm/i915/i915_gem_gtt.c +++ b/drivers/gpu/drm/i915/i915_gem_gtt.c @@ -3191,6 +3191,14 @@ int i915_gem_gtt_init(struct drm_device *dev) if (ret) return ret; + if ((ggtt->base.total - 1) >> 32) { + DRM_ERROR("We never expected a Global GTT with more than 32bits" + "of address space! Found %lldM!\n", + ggtt->base.total >> 20); + ggtt->base.total = 1ULL << 32; + ggtt->mappable_end = min(ggtt->mappable_end, ggtt->base.total); + } + /* * Initialise stolen early so that we may reserve preallocated * objects for the BIOS to KMS transition. -- 2.30.2