1 files changed, 11 insertions, 0 deletions

diff --git a/drivers/char/agp/amd64-agp.c b/drivers/char/agp/amd64-agp.c
index 25d64224cdbb..9e3939db76e8 100644
--- a/drivers/char/agp/amd64-agp.c
+++ b/drivers/char/agp/amd64-agp.c
@@ -312,6 +312,17 @@ static __devinit int fix_northbridge(struct pci_dev *nb, struct pci_dev *agp,
         pci_read_config_dword(agp, 0x10, &aper_low);
         pci_read_config_dword(agp, 0x14, &aper_hi);
         aper = (aper_low & ~((1<<22)-1)) | ((u64)aper_hi << 32);
+
+        /*
+         * On some sick chips APSIZE is 0. This means it wants 4G
+         * so let double check that order, and lets trust the AMD NB settings
+         */
+        if (aper + (32ULL<<(20 + order)) > 0x100000000ULL) {
+                printk(KERN_INFO "Aperture size %u MB is not right, using settings from NB\n",
+                                  32 << order);
+                order = nb_order;
+        }
+
         printk(KERN_INFO PFX "Aperture from AGP @ %Lx size %u MB\n", aper, 32 << order);
         if (order < 0 || !aperture_valid(aper, (32*1024*1024)<<order))
                 return -1;