[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, 3 insertions, 3 deletions

diff --git a/drivers/char/agp/backend.c b/drivers/char/agp/backend.c
index 2f3dfb63bdc6..4d4e602fdc7e 100644
--- a/drivers/char/agp/backend.c
+++ b/drivers/char/agp/backend.c
@@ -148,7 +148,7 @@ static int agp_backend_initialize(struct agp_bridge_data *bridge)
                         return -ENOMEM;
                 }
 
-                bridge->scratch_page_real = virt_to_phys(addr);
+                bridge->scratch_page_real = virt_to_gart(addr);
                 bridge->scratch_page =
                     bridge->driver->mask_memory(bridge, bridge->scratch_page_real, 0);
         }
@@ -189,7 +189,7 @@ static int agp_backend_initialize(struct agp_bridge_data *bridge)
 err_out:
         if (bridge->driver->needs_scratch_page)
                 bridge->driver->agp_destroy_page(
-                                phys_to_virt(bridge->scratch_page_real));
+                                gart_to_virt(bridge->scratch_page_real));
         if (got_gatt)
                 bridge->driver->free_gatt_table(bridge);
         if (got_keylist) {
@@ -214,7 +214,7 @@ static void agp_backend_cleanup(struct agp_bridge_data *bridge)
         if (bridge->driver->agp_destroy_page &&
             bridge->driver->needs_scratch_page)
                 bridge->driver->agp_destroy_page(
-                                phys_to_virt(bridge->scratch_page_real));
+                                gart_to_virt(bridge->scratch_page_real));
 }
 
 /* When we remove the global variable agp_bridge from all drivers