diff --git a/arch/x86/include/asm/pgtable_types.h b/arch/x86/include/asm/pgtable_types.h
index 54cb697..ef947d8 100644
--- a/arch/x86/include/asm/pgtable_types.h
+++ b/arch/x86/include/asm/pgtable_types.h
@@ -68,14 +68,22 @@
 			 _PAGE_DIRTY)
 
 /* Set of bits not changed in pte_modify */
-#define _PAGE_CHG_MASK	(PTE_PFN_MASK | _PAGE_PCD | _PAGE_PWT |		\
+#define _PAGE_CHG_MASK	(PTE_PFN_MASK | _PAGE_PAT | _PAGE_PCD | _PAGE_PWT | \
 			 _PAGE_SPECIAL | _PAGE_ACCESSED | _PAGE_DIRTY)
 
-#define _PAGE_CACHE_MASK	(_PAGE_PCD | _PAGE_PWT)
-#define _PAGE_CACHE_WB		(0)
-#define _PAGE_CACHE_WC		(_PAGE_PWT)
-#define _PAGE_CACHE_UC_MINUS	(_PAGE_PCD)
-#define _PAGE_CACHE_UC		(_PAGE_PCD | _PAGE_PWT)
+#define _PAGE_CACHE_MASK	(_PAGE_PAT | _PAGE_PCD | _PAGE_PWT)
+
+#ifndef __ASSEMBLY__
+extern unsigned __page_cache_wb;
+extern unsigned __page_cache_wc;
+extern unsigned __page_cache_uc_minus;
+extern unsigned __page_cache_uc;
+#endif
+
+#define _PAGE_CACHE_WB		__page_cache_wb
+#define _PAGE_CACHE_WC		__page_cache_wc
+#define _PAGE_CACHE_UC_MINUS	__page_cache_uc_minus
+#define _PAGE_CACHE_UC		__page_cache_uc
 
 #define PAGE_NONE	__pgprot(_PAGE_PROTNONE | _PAGE_ACCESSED)
 #define PAGE_SHARED	__pgprot(_PAGE_PRESENT | _PAGE_RW | _PAGE_USER | \
diff --git a/arch/x86/kernel/cpu/mtrr/generic.c b/arch/x86/kernel/cpu/mtrr/generic.c
index c66dda1..0137c05 100644
--- a/arch/x86/kernel/cpu/mtrr/generic.c
+++ b/arch/x86/kernel/cpu/mtrr/generic.c
@@ -304,6 +304,8 @@ void __init get_mtrr_state(void)
 	unsigned lo, dummy;
 	unsigned long flags;
 
+	printk(KERN_CRIT "pat: made it to get_mtrr_state\n");
+
 	vrs = mtrr_state.var_ranges;
 
 	rdmsr(MTRRcap_MSR, lo, dummy);
@@ -336,6 +338,7 @@ void __init get_mtrr_state(void)
 	local_irq_save(flags);
 	prepare_set();
 
+	printk(KERN_CRIT "pat: get_mtrr_state calling pat_init()\n");
 	pat_init();
 
 	post_set();
@@ -614,6 +617,7 @@ static void generic_set_all(void)
 	mask = set_mtrr_state();
 
 	/* also set PAT */
+	printk(KERN_CRIT "pat: generic_set_all() calling pat_init()\n");
 	pat_init();
 
 	post_set();
diff --git a/arch/x86/kernel/cpu/mtrr/main.c b/arch/x86/kernel/cpu/mtrr/main.c
index fd5ac04..6eee754 100644
--- a/arch/x86/kernel/cpu/mtrr/main.c
+++ b/arch/x86/kernel/cpu/mtrr/main.c
@@ -623,6 +623,8 @@ void __init mtrr_bp_init(void)
 {
 	u32 phys_addr;
 
+	printk(KERN_CRIT "pat: made it to mtrr_bp_init\n");
+
 	init_ifs();
 
 	phys_addr = 32;
@@ -690,16 +692,22 @@ void __init mtrr_bp_init(void)
 	}
 
 	if (mtrr_if) {
+		printk(KERN_CRIT "pat: in mtrr_bp_init and mtrr_if is true\n");
+
 		num_var_ranges = mtrr_if->num_var_ranges();
 		init_table();
 		if (use_intel()) {
+			printk(KERN_CRIT "pat: mtrr_bp_init calling get_mtrr_state\n");
 			get_mtrr_state();
 
 			if (mtrr_cleanup(phys_addr)) {
 				changed_by_mtrr_cleanup = 1;
+				printk(KERN_CRIT "pat: mtrr_bp_init calling %pF via set_all hook\n", &mtrr_if->set_all);
 				mtrr_if->set_all();
 			}
 
+		} else {
+			printk(KERN_CRIT "pat: in mtrr_bp_init but not use_intel()\n");
 		}
 	}
 }
@@ -720,6 +728,7 @@ void mtrr_ap_init(void)
 	 */
 	local_irq_save(flags);
 
+	printk(KERN_CRIT "pat: mtrr_ap_init calling %pF via set_all hook\n", &mtrr_if->set_all);
 	mtrr_if->set_all();
 
 	local_irq_restore(flags);
diff --git a/arch/x86/kernel/cpu/mtrr/xen.c b/arch/x86/kernel/cpu/mtrr/xen.c
index 50a45db..63f86aa 100644
--- a/arch/x86/kernel/cpu/mtrr/xen.c
+++ b/arch/x86/kernel/cpu/mtrr/xen.c
@@ -15,6 +15,8 @@ static void xen_set_mtrr(unsigned int reg, unsigned long base,
 	struct xen_platform_op op;
 	int error;
 
+	printk(KERN_CRIT "pat: xen_set_mtrr\n");
+
 	/* mtrr_ops->set() is called once per CPU,
 	 * but Xen's ops apply to all CPUs.
 	 */
@@ -87,7 +89,7 @@ static struct mtrr_ops xen_mtrr_ops = {
 	.get_free_region   = xen_get_free_region,
 	.validate_add_page = generic_validate_add_page,
 	.have_wrcomb       = positive_have_wrcomb,
-	.use_intel_if	   = 0,
+	.use_intel_if	   = 1/*0*/,
 	.num_var_ranges	   = xen_num_var_ranges,
 };
 
diff --git a/arch/x86/kernel/setup.c b/arch/x86/kernel/setup.c
index 1b1c851..f704078 100644
--- a/arch/x86/kernel/setup.c
+++ b/arch/x86/kernel/setup.c
@@ -834,6 +834,7 @@ void __init setup_arch(char **cmdline_p)
 	/* preallocate 4k for mptable mpc */
 	early_reserve_e820_mpc_new();
 	/* update e820 for memory not covered by WB MTRRs */
+	printk(KERN_CRIT "pat: calling mtrr_bp_init from setup_arch()\n");
 	mtrr_bp_init();
 	if (mtrr_trim_uncached_memory(max_pfn))
 		max_pfn = e820_end_of_ram_pfn();
diff --git a/arch/x86/mm/ioremap.c b/arch/x86/mm/ioremap.c
index 8a45093..3c13d64 100644
--- a/arch/x86/mm/ioremap.c
+++ b/arch/x86/mm/ioremap.c
@@ -141,18 +141,12 @@ int ioremap_change_attr(unsigned long vaddr, unsigned long size,
 	unsigned long nrpages = size >> PAGE_SHIFT;
 	int err;
 
-	switch (prot_val) {
-	case _PAGE_CACHE_UC:
-	default:
-		err = _set_memory_uc(vaddr, nrpages);
-		break;
-	case _PAGE_CACHE_WC:
+	if (prot_val == _PAGE_CACHE_WC)
 		err = _set_memory_wc(vaddr, nrpages);
-		break;
-	case _PAGE_CACHE_WB:
+	else if (prot_val == _PAGE_CACHE_WB)
 		err = _set_memory_wb(vaddr, nrpages);
-		break;
-	}
+	else /* _PAGE_CACHE_UC or "other" */
+		err = _set_memory_uc(vaddr, nrpages);
 
 	return err;
 }
@@ -256,21 +250,14 @@ static void __iomem *__ioremap_caller(resource_size_t phys_addr,
 		prot_val = new_prot_val;
 	}
 
-	switch (prot_val) {
-	case _PAGE_CACHE_UC:
-	default:
-		prot = PAGE_KERNEL_IO_NOCACHE;
-		break;
-	case _PAGE_CACHE_UC_MINUS:
-		prot = PAGE_KERNEL_IO_UC_MINUS;
-		break;
-	case _PAGE_CACHE_WC:
+	if (prot_val == _PAGE_CACHE_WC)
 		prot = PAGE_KERNEL_IO_WC;
-		break;
-	case _PAGE_CACHE_WB:
+	else if (prot_val == _PAGE_CACHE_WB)
 		prot = PAGE_KERNEL_IO;
-		break;
-	}
+	else if (prot_val == _PAGE_CACHE_UC_MINUS)
+		prot = PAGE_KERNEL_IO_UC_MINUS;
+	else /* _PAGE_CACHE_UC or "other" */
+		prot = PAGE_KERNEL_IO_NOCACHE;
 
 	/*
 	 * Ok, go for it..
diff --git a/arch/x86/mm/pat.c b/arch/x86/mm/pat.c
index 3f7886f..f85a273 100644
--- a/arch/x86/mm/pat.c
+++ b/arch/x86/mm/pat.c
@@ -61,6 +61,11 @@ __setup("debugpat", pat_debug_setup);
 
 static u64 __read_mostly boot_pat_state;
 
+unsigned __page_cache_wb;
+unsigned __page_cache_wc;
+unsigned __page_cache_uc_minus;
+unsigned __page_cache_uc;
+
 enum {
 	PAT_UC = 0,		/* uncached */
 	PAT_WC = 1,		/* Write combining */
@@ -70,15 +75,43 @@ enum {
 	PAT_UC_MINUS = 7,	/* UC, but can be overriden by MTRR */
 };
 
+const char *pat_labels[8] = {
+	"broken",
+	"broken",
+	"broken",
+	"broken",
+	"broken",
+	"broken",
+	"broken",
+	"broken"
+};
+
 #define PAT(x, y)	((u64)PAT_ ## y << ((x)*8))
 
+static unsigned find_pat_index(const u64 pat, int mode)
+{
+	u64 mask;
+	int i;
+
+	for (mask = 0x7, i = 0; i < 8; mask <<= 8, i++) {
+		if (((pat & mask)>>(i*8)) == mode)
+			return i;
+	}
+	return -1; /* OR??? */
+}
+
 void pat_init(void)
 {
 	u64 pat;
 
-	if (!pat_enabled)
+	printk(KERN_CRIT "%s\n", __func__);
+	dump_stack();
+	if (!pat_enabled) {
+		printk(KERN_CRIT "%s pat not enabled\n", __func__);
 		return;
+	}
 
+	printk(KERN_CRIT "%s:%d\n", __func__, __LINE__);
 	if (!cpu_has_pat) {
 		if (!boot_pat_state) {
 			pat_disable("PAT not supported by CPU.");
@@ -95,6 +128,8 @@ void pat_init(void)
 		}
 	}
 
+	printk(KERN_CRIT "%s:%d\n", __func__, __LINE__);
+
 	/* Set PWT to Write-Combining. All other bits stay the same */
 	/*
 	 * PTE encoding used in Linux:
@@ -105,32 +140,41 @@ void pat_init(void)
 	 *      000 WB		_PAGE_CACHE_WB
 	 *      001 WC		_PAGE_CACHE_WC
 	 *      010 UC-		_PAGE_CACHE_UC_MINUS
-	 *      011 UC		_PAGE_CACHE_UC
-	 * PAT bit unused
+	 *      011 UC		_PAGE_CACHE_UC PAT bit unused
 	 */
 	pat = PAT(0, WB) | PAT(1, WC) | PAT(2, UC_MINUS) | PAT(3, UC) |
-	      PAT(4, WB) | PAT(5, WC) | PAT(6, UC_MINUS) | PAT(7, UC);
+		PAT(4, WB) | PAT(5, WC) | PAT(6, UC_MINUS) | PAT(7, UC);
 
 	/* Boot CPU check */
 	if (!boot_pat_state)
 		rdmsrl(MSR_IA32_CR_PAT, boot_pat_state);
 
 	wrmsrl(MSR_IA32_CR_PAT, pat);
+
+
+	/* Now see what we actually got */
+	rdmsrl(MSR_IA32_CR_PAT, pat);
+	__page_cache_wb = find_pat_index(pat, PAT_WB);
+	__page_cache_wc = find_pat_index(pat, PAT_WC);
+	__page_cache_uc_minus = find_pat_index(pat, PAT_UC_MINUS);
+	__page_cache_uc = find_pat_index(pat, PAT_UC);
+
+	pat_labels[__page_cache_wb] = "write-back";
+	pat_labels[__page_cache_wc] = "write-combining";
+	pat_labels[__page_cache_uc_minus] = "uncached-minus";
+	pat_labels[__page_cache_uc] = "uncached";
+
 	printk(KERN_INFO "x86 PAT enabled: cpu %d, old 0x%Lx, new 0x%Lx\n",
 	       smp_processor_id(), boot_pat_state, pat);
+	printk(KERN_INFO "Indexes: WB:%d; WC:%d; UC-:%d; UC:%d\n",
+	       __page_cache_wb, __page_cache_wc, __page_cache_uc_minus, __page_cache_uc);
 }
 
 #undef PAT
 
 static char *cattr_name(unsigned long flags)
 {
-	switch (flags & _PAGE_CACHE_MASK) {
-	case _PAGE_CACHE_UC:		return "uncached";
-	case _PAGE_CACHE_UC_MINUS:	return "uncached-minus";
-	case _PAGE_CACHE_WB:		return "write-back";
-	case _PAGE_CACHE_WC:		return "write-combining";
-	default:			return "broken";
-	}
+	return pat_labels[flags & _PAGE_CACHE_MASK];
 }
 
 /*
diff --git a/arch/x86/xen/enlighten.c b/arch/x86/xen/enlighten.c
index e099e44..232ed3e 100644
--- a/arch/x86/xen/enlighten.c
+++ b/arch/x86/xen/enlighten.c
@@ -1121,7 +1121,7 @@ asmlinkage void __init xen_start_kernel(void)
 		xen_start_info->console.domU.evtchn = 0;
 	}
 
-	pat_disable("PAT disabled on Xen");
+	//pat_disable("PAT disabled on Xen");
 
 	xen_raw_console_write("about to get started...\n");