Fix bug #4908 for now. Alternative is highlighted in this bug report as the

    better future direction.

diff --git a/linux-core/drm_bufs.c b/linux-core/drm_bufs.c
index 5e1fca1..5e70e47 100644 (file)
--- a/linux-core/drm_bufs.c
+++ b/linux-core/drm_bufs.c
@@ -235,9 +235,19 @@ int drm_addmap_core(drm_device_t * dev, unsigned int offset,
 #ifdef __alpha__
                map->offset += dev->hose->mem_space->start;
 #endif
+               /* Note: dev->agp->base may actually be 0 when the DRM
+                * is not in control of AGP space. But if user space is
+                * it should already have added the AGP base itself.
+                */
                map->offset += dev->agp->base;
                map->mtrr = dev->agp->agp_mtrr; /* for getmap */
 
+               /* This assumes the DRM is in total control of AGP space.
+                * It's not always the case as AGP can be in the control
+                * of user space (i.e. i810 driver). So this loop will get
+                * skipped and we double check that dev->agp->memory is
+                * actually set as well as being invalid before EPERM'ing
+                */
                for (entry = dev->agp->memory; entry; entry = entry->next) {
                        if ((map->offset >= entry->bound) &&
                            (map->offset + map->size <= entry->bound + entry->pages * PAGE_SIZE)) {
@@ -245,7 +255,7 @@ int drm_addmap_core(drm_device_t * dev, unsigned int offset,
                                break;
                        }
                }
-               if (!valid) {
+               if (dev->agp->memory && !valid) {
                        drm_free(map, sizeof(*map), DRM_MEM_MAPS);
                        return -EPERM;
                }
@@ -599,7 +609,7 @@ int drm_addbufs_agp(drm_device_t * dev, drm_buf_desc_t * request)
                        break;
                }
        }
-       if (!valid) {
+       if (dev->agp->memory && !valid) {
                DRM_DEBUG("zone invalid\n");
                return -EINVAL;
        }