--- linux-2.5.72-orig/include/asm-ia64/io.h	2003-06-20 14:40:35.000000000 -0600
+++ linux-2.5.72/include/asm-ia64/io.h	2003-06-27 09:12:44.000000000 -0600
@@ -424,6 +424,6 @@
  * which is precisely what we want.
  */
 extern unsigned long ia64_max_iommu_merge_mask;
-#define BIO_VMERGE_BOUNDARY	(0UL)//(ia64_max_iommu_merge_mask + 1)
+#define BIO_VMERGE_BOUNDARY	(ia64_max_iommu_merge_mask + 1)
 
 #endif /* _ASM_IA64_IO_H */
--- linux-2.5.72-orig/arch/ia64/hp/common/sba_iommu.c	2003-06-20 14:40:31.000000000 -0600
+++ linux-2.5.72/arch/ia64/hp/common/sba_iommu.c	2003-06-27 09:09:50.000000000 -0600
@@ -47,8 +47,11 @@
 /*
 ** This option allows cards capable of 64bit DMA to bypass the IOMMU.  If
 ** not defined, all DMA will be 32bit and go through the TLB.
+** The bio merge code currently expects that if we tweak that vmerge
+** boundary that we will alway coalesce blocks on that boundary.  Enabling
+** this optimization is therefore incompatible with tuning the boundary.
 */
-#define ALLOW_IOV_BYPASS
+#undef ALLOW_IOV_BYPASS
 
 /*
 ** If a device prefetches beyond the end of a valid pdir entry, it will cause