Fix software I/O TLB to always return <4GB memory for alloc_consistent().

arch/ia64/Config.help

@@ -414,12 +414,18 @@ CONFIG_IA64_GENERIC
 
   HP-simulator   For the HP simulator
                  (<http://software.hp.com/ia64linux/>).
+  HP-zx1         For HP zx1 platforms.
   SN1-simulator  For the SGI SN1 simulator.
   DIG-compliant  For DIG ("Developer's Interface Guide") compliant
-                 system.
+                 systems.
 
   If you don't know what to do, choose "generic".
 
+CONFIG_IA64_HP_ZX1
+  Build a kernel that runs on HP zx1-based systems.  This adds support
+  for the zx1 IOMMU and makes root bus bridges appear in PCI config space
+  (required for zx1 agpgart support).
+
 CONFIG_IA64_PAGE_SIZE_4KB
   This lets you select the page size of the kernel.  For best IA-64
   performance, a page size of 8KB or 16KB is recommended.  For best

arch/ia64/lib/swiotlb.c

@@ -276,7 +276,10 @@ swiotlb_alloc_consistent (struct pci_dev *hwdev, size_t size, dma_addr_t *dma_ha
 	int gfp = GFP_ATOMIC;
 	void *ret;
 
-	if (!hwdev || hwdev->dma_mask <= 0xffffffff)
+	/*
+	 * Alloc_consistent() is defined to return memory < 4GB, no matter what the DMA
+	 * mask says.
+	 */
 	gfp |= GFP_DMA; /* XXX fix me: should change this to GFP_32BIT or ZONE_32BIT */
 	ret = (void *)__get_free_pages(gfp, get_order(size));
 	if (!ret)