[PATCH] drm/ttm: device address space != CPU address space

Alex Deucher alexdeucher at gmail.com
Tue Mar 3 21:18:38 PST 2015

We need to store device offsets in 64 bit as the device
address space may be larger than the CPU's.

Fixes GPU init failures on radeons with 4GB or more of
vram on 32 bit kernels.  We put vram at the start of the
GPU's address space so the gart aperture starts at 4 GB
causing all GPU addresses in the gart aperture to get


Signed-off-by: Alex Deucher <alexander.deucher at amd.com>
Cc: thellstrom at vmware.com
Untested.  Someone more familiar with the ttm internals can
probably point out any additional bits I missed.  Heading to
bed now.

 drivers/gpu/drm/ttm/ttm_bo.c    | 2 +-
 include/drm/ttm/ttm_bo_api.h    | 2 +-
 include/drm/ttm/ttm_bo_driver.h | 2 +-
 3 files changed, 3 insertions(+), 3 deletions(-)

diff --git a/drivers/gpu/drm/ttm/ttm_bo.c b/drivers/gpu/drm/ttm/ttm_bo.c
index d395b0b..8d9b7de 100644
--- a/drivers/gpu/drm/ttm/ttm_bo.c
+++ b/drivers/gpu/drm/ttm/ttm_bo.c
@@ -74,7 +74,7 @@ static void ttm_mem_type_debug(struct ttm_bo_device *bdev, int mem_type)
 	pr_err("    has_type: %d\n", man->has_type);
 	pr_err("    use_type: %d\n", man->use_type);
 	pr_err("    flags: 0x%08X\n", man->flags);
-	pr_err("    gpu_offset: 0x%08lX\n", man->gpu_offset);
+	pr_err("    gpu_offset: 0x%08llX\n", man->gpu_offset);
 	pr_err("    size: %llu\n", man->size);
 	pr_err("    available_caching: 0x%08X\n", man->available_caching);
 	pr_err("    default_caching: 0x%08X\n", man->default_caching);
diff --git a/include/drm/ttm/ttm_bo_api.h b/include/drm/ttm/ttm_bo_api.h
index 0ccf7f2..c768ddf 100644
--- a/include/drm/ttm/ttm_bo_api.h
+++ b/include/drm/ttm/ttm_bo_api.h
@@ -249,7 +249,7 @@ struct ttm_buffer_object {
 	 * either of these locks held.
-	unsigned long offset;
+	uint64_t offset; /* GPU address space is independent of CPU word size */
 	uint32_t cur_placement;
 	struct sg_table *sg;
diff --git a/include/drm/ttm/ttm_bo_driver.h b/include/drm/ttm/ttm_bo_driver.h
index 142d752..813042c 100644
--- a/include/drm/ttm/ttm_bo_driver.h
+++ b/include/drm/ttm/ttm_bo_driver.h
@@ -277,7 +277,7 @@ struct ttm_mem_type_manager {
 	bool has_type;
 	bool use_type;
 	uint32_t flags;
-	unsigned long gpu_offset;
+	uint64_t gpu_offset; /* GPU address space is independent of CPU word size */
 	uint64_t size;
 	uint32_t available_caching;
 	uint32_t default_caching;

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