1 files changed, 15 insertions, 4 deletions

diff --git a/arch/x86_64/kernel/pci-gart.c b/arch/x86_64/kernel/pci-gart.c
index c37fc7726ba6..2fe23a6c361b 100644
--- a/arch/x86_64/kernel/pci-gart.c
+++ b/arch/x86_64/kernel/pci-gart.c
@@ -457,9 +457,12 @@ int gart_map_sg(struct device *dev, struct scatterlist *sg, int nents, int dir)
 error:
         flush_gart(NULL);
         gart_unmap_sg(dev, sg, nents, dir);
-        /* When it was forced try again unforced */
-        if (force_iommu) 
-                return dma_map_sg_nonforce(dev, sg, nents, dir);
+        /* When it was forced or merged try again in a dumb way */
+        if (force_iommu || iommu_merge) {
+                out = dma_map_sg_nonforce(dev, sg, nents, dir);
+                if (out > 0)
+                        return out;
+        }
         if (panic_on_overflow)
                 panic("dma_map_sg: overflow on %lu pages\n", pages);
         iommu_full(dev, pages << PAGE_SHIFT, dir);
@@ -642,9 +645,18 @@ static int __init pci_iommu_init(void)
             (no_agp && init_k8_gatt(&info) < 0)) {
                 no_iommu = 1;
                 no_iommu_init();
+                printk(KERN_INFO "PCI-DMA: Disabling IOMMU.\n");
+                if (end_pfn > MAX_DMA32_PFN) {
+                        printk(KERN_ERR "WARNING more than 4GB of memory "
+                                        "but IOMMU not compiled in.\n"
+                               KERN_ERR "WARNING 32bit PCI may malfunction.\n"
+                               KERN_ERR "You might want to enable "
+                                        "CONFIG_GART_IOMMU\n");
+                }
                 return -1;
         }
 
+        printk(KERN_INFO "PCI-DMA: using GART IOMMU.\n");
         aper_size = info.aper_size * 1024 * 1024;       
         iommu_size = check_iommu_size(info.aper_base, aper_size); 
         iommu_pages = iommu_size >> PAGE_SHIFT; 
@@ -718,7 +730,6 @@ static int __init pci_iommu_init(void)
                      
         flush_gart(NULL);
 
-        printk(KERN_INFO "PCI-DMA: using GART IOMMU.\n");
         dma_ops = &gart_dma_ops;
 
         return 0;