[PATCH] AGP fix for Xen VMM

When Linux is running on the Xen virtual machine monitor, physical
addresses are virtualised and cannot be directly referenced by the AGP
GART.  This patch fixes the GART driver for Xen by adding a layer of
abstraction between physical addresses and 'GART addresses'.

Architecture-specific functions are also defined for allocating and freeing
the GATT.  Xen requires this to ensure that table really is contiguous from
the point of view of the GART.

These extra interface functions are defined as 'no-ops' for all existing
architectures that use the GART driver.

Signed-off-by: Keir Fraser <keir@xensource.com>
Signed-off-by: Andrew Morton <akpm@osdl.org>
Signed-off-by: Dave Jones <davej@redhat.com>

1 files changed, 10 insertions, 0 deletions

diff --git a/include/asm-alpha/agp.h b/include/asm-alpha/agp.h
index c99dbbb5bcb5..ef855a3bc0f5 100644
--- a/include/asm-alpha/agp.h
+++ b/include/asm-alpha/agp.h
@@ -10,4 +10,14 @@
 #define flush_agp_mappings() 
 #define flush_agp_cache() mb()
 
+/* Convert a physical address to an address suitable for the GART. */
+#define phys_to_gart(x) (x)
+#define gart_to_phys(x) (x)
+
+/* GATT allocation. Returns/accepts GATT kernel virtual address. */
+#define alloc_gatt_pages(order)         \
+        ((char *)__get_free_pages(GFP_KERNEL, (order)))
+#define free_gatt_pages(table, order)   \
+        free_pages((unsigned long)(table), (order))
+
 #endif