diff --git a/hw/Makefile.objs b/hw/Makefile.objs
index af4ab0c..be9ef83 100644
--- a/hw/Makefile.objs
+++ b/hw/Makefile.objs
@@ -37,6 +37,7 @@ common-obj-$(CONFIG_SMARTCARD) += ccid-card-passthru.o
 common-obj-$(CONFIG_SMARTCARD_NSS) += ccid-card-emulated.o
 common-obj-$(CONFIG_I8259) += i8259_common.o i8259.o
 common-obj-y += fifo.o
+common-obj-y += pam.o
 
 # PPC devices
 common-obj-$(CONFIG_PREP_PCI) += prep_pci.o
diff --git a/hw/pam.c b/hw/pam.c
new file mode 100644
index 0000000..a95e2cf
--- /dev/null
+++ b/hw/pam.c
@@ -0,0 +1,87 @@
+/*
+ * QEMU i440FX/PIIX3 PCI Bridge Emulation
+ *
+ * Copyright (c) 2006 Fabrice Bellard
+ * Copyright (c) 2011 Isaku Yamahata <yamahata at valinux co jp>
+ *                    VA Linux Systems Japan K.K.
+ * Copyright (c) 2012 Jason Baron <jbaron@redhat.com>
+ *
+ * Split out from piix_pci.c
+ *
+ * Permission is hereby granted, free of charge, to any person obtaining a copy
+ * of this software and associated documentation files (the "Software"), to deal
+ * in the Software without restriction, including without limitation the rights
+ * to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
+ * copies of the Software, and to permit persons to whom the Software is
+ * furnished to do so, subject to the following conditions:
+ *
+ * The above copyright notice and this permission notice shall be included in
+ * all copies or substantial portions of the Software.
+ *
+ * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
+ * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
+ * FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL
+ * THE AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
+ * LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
+ * OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN
+ * THE SOFTWARE.
+ */
+#include "sysemu.h"
+#include "pam.h"
+
+void smram_update(MemoryRegion *smram_region, uint8_t smram,
+                  uint8_t smm_enabled)
+{
+    bool smram_enabled;
+
+    smram_enabled = ((smm_enabled && (smram & SMRAM_G_SMRAME)) ||
+                        (smram & SMRAM_D_OPEN));
+    memory_region_set_enabled(smram_region, !smram_enabled);
+}
+
+void smram_set_smm(uint8_t *host_smm_enabled, int smm, uint8_t smram,
+                   MemoryRegion *smram_region)
+{
+    uint8_t smm_enabled = (smm != 0);
+    if (*host_smm_enabled != smm_enabled) {
+        *host_smm_enabled = smm_enabled;
+        smram_update(smram_region, smram, *host_smm_enabled);
+    }
+}
+
+void init_pam(MemoryRegion *ram_memory, MemoryRegion *system_memory,
+              MemoryRegion *pci_address_space, PAMMemoryRegion *mem,
+              uint32_t start, uint32_t size)
+{
+    int i;
+
+    /* RAM */
+    memory_region_init_alias(&mem->alias[3], "pam-ram", ram_memory,
+                             start, size);
+    /* ROM (XXX: not quite correct) */
+    memory_region_init_alias(&mem->alias[1], "pam-rom", ram_memory,
+                             start, size);
+    memory_region_set_readonly(&mem->alias[1], true);
+
+    /* XXX: should distinguish read/write cases */
+    memory_region_init_alias(&mem->alias[0], "pam-pci", pci_address_space,
+                             start, size);
+    memory_region_init_alias(&mem->alias[2], "pam-pci", pci_address_space,
+                             start, size);
+
+    for (i = 0; i < 4; ++i) {
+        memory_region_set_enabled(&mem->alias[i], false);
+        memory_region_add_subregion_overlap(system_memory, start,
+                                            &mem->alias[i], 1);
+    }
+    mem->current = 0;
+}
+
+void pam_update(PAMMemoryRegion *pam, int idx, uint8_t val)
+{
+    assert(0 <= idx && idx <= 12);
+
+    memory_region_set_enabled(&pam->alias[pam->current], false);
+    pam->current = (val >> ((!(idx & 1)) * 4)) & PAM_ATTR_MASK;
+    memory_region_set_enabled(&pam->alias[pam->current], true);
+}
diff --git a/hw/pam.h b/hw/pam.h
new file mode 100644
index 0000000..2d77ebe
--- /dev/null
+++ b/hw/pam.h
@@ -0,0 +1,97 @@
+#ifndef QEMU_PAM_H
+#define QEMU_PAM_H
+
+/*
+ * Copyright (c) 2006 Fabrice Bellard
+ * Copyright (c) 2011 Isaku Yamahata <yamahata at valinux co jp>
+ *               VA Linux Systems Japan K.K.
+ * Copyright (c) 2012 Jason Baron <jbaron@redhat.com>
+ *
+ * Split out from piix_pci.c
+ *
+ * Permission is hereby granted, free of charge, to any person obtaining a copy
+ * of this software and associated documentation files (the "Software"), to deal
+ * in the Software without restriction, including without limitation the rights
+ * to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
+ * copies of the Software, and to permit persons to whom the Software is
+ * furnished to do so, subject to the following conditions:
+ *
+ * The above copyright notice and this permission notice shall be included in
+ * all copies or substantial portions of the Software.
+ *
+ * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
+ * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
+ * FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL
+ * THE AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
+ * LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
+ * OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN
+ * THE SOFTWARE.
+ */
+
+/*
+ * SMRAM memory area and PAM memory area in Legacy address range for PC.
+ * PAM: Programmable Attribute Map registers
+ *
+ * 0xa0000 - 0xbffff compatible SMRAM
+ *
+ * 0xc0000 - 0xc3fff Expansion area memory segments
+ * 0xc4000 - 0xc7fff
+ * 0xc8000 - 0xcbfff
+ * 0xcc000 - 0xcffff
+ * 0xd0000 - 0xd3fff
+ * 0xd4000 - 0xd7fff
+ * 0xd8000 - 0xdbfff
+ * 0xdc000 - 0xdffff
+ * 0xe0000 - 0xe3fff Extended System BIOS Area Memory Segments
+ * 0xe4000 - 0xe7fff
+ * 0xe8000 - 0xebfff
+ * 0xec000 - 0xeffff
+ *
+ * 0xf0000 - 0xfffff System BIOS Area Memory Segments
+ */
+
+#include "qemu-common.h"
+#include "memory.h"
+
+#define SMRAM_C_BASE    0xa0000
+#define SMRAM_C_END     0xc0000
+#define SMRAM_C_SIZE    0x20000
+
+#define PAM_EXPAN_BASE  0xc0000
+#define PAM_EXPAN_SIZE  0x04000
+
+#define PAM_EXBIOS_BASE 0xe0000
+#define PAM_EXBIOS_SIZE 0x04000
+
+#define PAM_BIOS_BASE   0xf0000
+#define PAM_BIOS_END    0xfffff
+/* 64KB: Intel 3 series express chipset family p. 58*/
+#define PAM_BIOS_SIZE   0x10000
+
+/* PAM registers: log nibble and high nibble*/
+#define PAM_ATTR_WE     ((uint8_t)2)
+#define PAM_ATTR_RE     ((uint8_t)1)
+#define PAM_ATTR_MASK   ((uint8_t)3)
+
+/* SMRAM register */
+#define SMRAM_D_OPEN           ((uint8_t)(1 << 6))
+#define SMRAM_D_CLS            ((uint8_t)(1 << 5))
+#define SMRAM_D_LCK            ((uint8_t)(1 << 4))
+#define SMRAM_G_SMRAME         ((uint8_t)(1 << 3))
+#define SMRAM_C_BASE_SEG_MASK  ((uint8_t)0x7)
+#define SMRAM_C_BASE_SEG       ((uint8_t)0x2)  /* hardwired to b010 */
+
+typedef struct PAMMemoryRegion {
+    MemoryRegion alias[4];  /* index = PAM value */
+    unsigned current;
+} PAMMemoryRegion;
+
+void smram_update(MemoryRegion *smram_region, uint8_t smram,
+                  uint8_t smm_enabled);
+void smram_set_smm(uint8_t *host_smm_enabled, int smm, uint8_t smram,
+                   MemoryRegion *smram_region);
+void init_pam(MemoryRegion *ram, MemoryRegion *system, MemoryRegion *pci,
+              PAMMemoryRegion *mem, uint32_t start, uint32_t size);
+void pam_update(PAMMemoryRegion *mem, int idx, uint8_t val);
+
+#endif /* QEMU_PAM_H */
diff --git a/hw/piix_pci.c b/hw/piix_pci.c
index 9af5847..ba1b3de 100644
--- a/hw/piix_pci.c
+++ b/hw/piix_pci.c
@@ -30,6 +30,7 @@
 #include "sysbus.h"
 #include "range.h"
 #include "xen.h"
+#include "pam.h"
 
 /*
  * I440FX chipset data sheet.
@@ -68,11 +69,6 @@ typedef struct PIIX3State {
     int32_t pci_irq_levels_vmstate[PIIX_NUM_PIRQS];
 } PIIX3State;
 
-typedef struct PAMMemoryRegion {
-    MemoryRegion alias[4];  /* index = PAM value */
-    unsigned current;
-} PAMMemoryRegion;
-
 struct PCII440FXState {
     PCIDevice dev;
     MemoryRegion *system_memory;
@@ -105,52 +101,16 @@ static int pci_slot_get_pirq(PCIDevice *pci_dev, int pci_intx)
     return (pci_intx + slot_addend) & 3;
 }
 
-static void init_pam(PCII440FXState *d, PAMMemoryRegion *mem,
-                     uint32_t start, uint32_t size)
-{
-    int i;
-
-    /* RAM */
-    memory_region_init_alias(&mem->alias[3], "pam-ram", d->ram_memory, start, size);
-    /* ROM (XXX: not quite correct) */
-    memory_region_init_alias(&mem->alias[1], "pam-rom", d->ram_memory, start, size);
-    memory_region_set_readonly(&mem->alias[1], true);
-
-    /* XXX: should distinguish read/write cases */
-    memory_region_init_alias(&mem->alias[0], "pam-pci", d->pci_address_space,
-                             start, size);
-    memory_region_init_alias(&mem->alias[2], "pam-pci", d->pci_address_space,
-                             start, size);
-
-    for (i = 0; i < 4; ++i) {
-        memory_region_set_enabled(&mem->alias[i], false);
-        memory_region_add_subregion_overlap(d->system_memory, start, &mem->alias[i], 1);
-    }
-    mem->current = 0;
-}
-
-static void update_pam(PAMMemoryRegion *pam, unsigned r)
-{
-    memory_region_set_enabled(&pam->alias[pam->current], false);
-    pam->current = r;
-    memory_region_set_enabled(&pam->alias[pam->current], true);
-}
-
 static void i440fx_update_memory_mappings(PCII440FXState *d)
 {
-    int i, r;
-    uint32_t smram;
-    bool smram_enabled;
+    int i;
 
     memory_region_transaction_begin();
-    update_pam(&d->pam_regions[0], (d->dev.config[I440FX_PAM] >> 4) & 3);
-    for(i = 0; i < 12; i++) {
-        r = (d->dev.config[(i >> 1) + (I440FX_PAM + 1)] >> ((i & 1) * 4)) & 3;
-        update_pam(&d->pam_regions[i+1], r);
+    for (i = 0; i < 13; i++) {
+        pam_update(&d->pam_regions[i], i,
+                   d->dev.config[I440FX_PAM + ((i + 1) / 2)]);
     }
-    smram = d->dev.config[I440FX_SMRAM];
-    smram_enabled = (d->smm_enabled && (smram & 0x08)) || (smram & 0x40);
-    memory_region_set_enabled(&d->smram_region, !smram_enabled);
+    smram_update(&d->smram_region, d->dev.config[I440FX_SMRAM], d->smm_enabled);
     memory_region_transaction_commit();
 }
 
@@ -158,11 +118,10 @@ static void i440fx_set_smm(int val, void *arg)
 {
     PCII440FXState *d = arg;
 
-    val = (val != 0);
-    if (d->smm_enabled != val) {
-        d->smm_enabled = val;
-        i440fx_update_memory_mappings(d);
-    }
+    memory_region_transaction_begin();
+    smram_set_smm(&d->smm_enabled, val, d->dev.config[I440FX_SMRAM],
+                  &d->smram_region);
+    memory_region_transaction_commit();
 }
 
 
@@ -300,9 +259,12 @@ static PCIBus *i440fx_common_init(const char *device_name,
     memory_region_add_subregion_overlap(f->system_memory, 0xa0000,
                                         &f->smram_region, 1);
     memory_region_set_enabled(&f->smram_region, false);
-    init_pam(f, &f->pam_regions[0], 0xf0000, 0x10000);
+    init_pam(f->ram_memory, f->system_memory, f->pci_address_space,
+             &f->pam_regions[0], PAM_BIOS_BASE, PAM_BIOS_SIZE);
     for (i = 0; i < 12; ++i) {
-        init_pam(f, &f->pam_regions[i+1], 0xc0000 + i * 0x4000, 0x4000);
+        init_pam(f->ram_memory, f->system_memory, f->pci_address_space,
+                 &f->pam_regions[i+1], PAM_EXPAN_BASE + i * PAM_EXPAN_SIZE,
+                 PAM_EXPAN_SIZE);
     }
 
     /* Xen supports additional interrupt routes from the PCI devices to
