linux-kernel - [079/114] drm/agp/i915: trim stolen space to 32M

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Date:	Tue, 24 Aug 2010 15:45:24 -0700
From:	Greg KH <gregkh@...e.de>
To:	linux-kernel@...r.kernel.org, stable@...nel.org
Cc:	stable-review@...nel.org, torvalds@...ux-foundation.org,
	akpm@...ux-foundation.org, alan@...rguk.ukuu.org.uk,
	Jesse Barnes <jbarnes@...tuousgeek.org>,
	Eric Anholt <eric@...olt.net>
Subject: [079/114] drm/agp/i915: trim stolen space to 32M

2.6.35-stable review patch.  If anyone has any objections, please let us know.

------------------

From: Jesse Barnes <jbarnes@...tuousgeek.org>

commit d1d6ca73ef548748e141747e7260798327d6a2c1 upstream.

Some BIOSes will claim a large chunk of stolen space.  Unless we
reclaim it, our aperture for remapping buffer objects will be
constrained.  So clamp the stolen space to 32M and ignore the rest.

Fixes https://bugzilla.kernel.org/show_bug.cgi?id=15469 among others.

Adding the ignored stolen memory back into the general pool using the
memory hotplug code is left as an exercise for the reader.

Signed-off-by: Jesse Barnes <jbarnes@...tuousgeek.org>
Reviewed-by: Simon Farnsworth <simon.farnsworth@...lan.com>
Tested-by: Artem S. Tashkinov <t.artem@...lcity.com>
Signed-off-by: Eric Anholt <eric@...olt.net>
Signed-off-by: Greg Kroah-Hartman <gregkh@...e.de>

---
 drivers/char/agp/intel-gtt.c    |   11 ++++++++++-
 drivers/gpu/drm/i915/i915_dma.c |    8 ++++++++
 2 files changed, 18 insertions(+), 1 deletion(-)

--- a/drivers/char/agp/intel-gtt.c
+++ b/drivers/char/agp/intel-gtt.c
@@ -25,6 +25,10 @@
 #define USE_PCI_DMA_API 1
 #endif
 
+/* Max amount of stolen space, anything above will be returned to Linux */
+int intel_max_stolen = 32 * 1024 * 1024;
+EXPORT_SYMBOL(intel_max_stolen);
+
 static const struct aper_size_info_fixed intel_i810_sizes[] =
 {
 	{64, 16384, 4},
@@ -710,7 +714,12 @@ static void intel_i830_init_gtt_entries(
 			break;
 		}
 	}
-	if (gtt_entries > 0) {
+	if (!local && gtt_entries > intel_max_stolen) {
+		dev_info(&agp_bridge->dev->dev,
+			 "detected %dK stolen memory, trimming to %dK\n",
+			 gtt_entries / KB(1), intel_max_stolen / KB(1));
+		gtt_entries = intel_max_stolen / KB(4);
+	} else if (gtt_entries > 0) {
 		dev_info(&agp_bridge->dev->dev, "detected %dK %s memory\n",
 		       gtt_entries / KB(1), local ? "local" : "stolen");
 		gtt_entries /= KB(4);
--- a/drivers/gpu/drm/i915/i915_dma.c
+++ b/drivers/gpu/drm/i915/i915_dma.c
@@ -40,6 +40,8 @@
 #include <linux/vga_switcheroo.h>
 #include <linux/slab.h>
 
+extern int intel_max_stolen; /* from AGP driver */
+
 /**
  * Sets up the hardware status page for devices that need a physical address
  * in the register.
@@ -2104,6 +2106,12 @@ int i915_driver_load(struct drm_device *
 	if (ret)
 		goto out_iomapfree;
 
+	if (prealloc_size > intel_max_stolen) {
+		DRM_INFO("detected %dM stolen memory, trimming to %dM\n",
+			 prealloc_size >> 20, intel_max_stolen >> 20);
+		prealloc_size = intel_max_stolen;
+	}
+
 	dev_priv->wq = create_singlethread_workqueue("i915");
 	if (dev_priv->wq == NULL) {
 		DRM_ERROR("Failed to create our workqueue.\n");


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