diff -r 059c01d69a08 tools/libxc/xc_dom_x86.c
--- a/tools/libxc/xc_dom_x86.c	Thu Oct 29 14:48:28 2009 +0000
+++ b/tools/libxc/xc_dom_x86.c	Mon Nov 02 15:37:42 2009 +0800
@@ -639,7 +639,7 @@
     xc_dom_register_arch_hooks(&xc_dom_64);
 }
 
-static int x86_compat(int xc, domid_t domid, char *guest_type)
+static int x86_compat(int xc, domid_t domid, char *guest_type, int *guest_size)
 {
     static const struct {
         char           *guest;
@@ -660,6 +660,7 @@
     if ( domctl.u.address_size.size == 0 )
         /* nothing to do */
         return 0;
+    *guest_size = domctl.u.address_size.size;
 
     xc_dom_printf("%s: guest %s, address size %" PRId32 "\n", __FUNCTION__,
                   guest_type, domctl.u.address_size.size);
@@ -696,10 +697,11 @@
 
 int arch_setup_meminit(struct xc_dom_image *dom)
 {
-    int rc;
+    int rc, host_64bit=0, mem_128_limit=0, guest_size=0;
     xen_pfn_t pfn, allocsz, i, j, mfn;
+    xc_physinfo_t put_info;
 
-    rc = x86_compat(dom->guest_xc, dom->guest_domid, dom->guest_type);
+    rc = x86_compat(dom->guest_xc, dom->guest_domid, dom->guest_type, &guest_size);
     if ( rc )
         return rc;
     if ( xc_dom_feature_translated(dom) )
@@ -740,6 +742,12 @@
         for ( pfn = 0; pfn < dom->total_pages; pfn++ )
             dom->p2m_host[pfn] = pfn;
         
+        xc_physinfo(dom->guest_xc, &put_info);
+        if((put_info.total_pages * (XC_PAGE_SIZE / 1024))/(1024*1024) > 128)
+            mem_128_limit = 1;
+
+        if(strstr(dom->xen_caps, "x86_64") != NULL)
+            host_64bit=1;
         /* allocate guest memory */
         for ( i = rc = allocsz = 0;
               (i < dom->total_pages) && !rc;
@@ -751,6 +759,22 @@
             rc = xc_domain_memory_populate_physmap(
                 dom->guest_xc, dom->guest_domid, allocsz,
                 0, 0, &dom->p2m_host[i]);
+            if((host_64bit == 1) && (mem_128_limit))
+            {
+                if( (guest_size == 32) )// 32bit guest 
+                    rc = xc_domain_memory_populate_physmap(
+                        dom->guest_xc, dom->guest_domid, allocsz, 0, XENMEMF_address_bits(37), &dom->p2m_host[i]);
+                else if( (guest_size == 64) );//64bit 
+                    rc = xc_domain_memory_populate_physmap(
+                        dom->guest_xc, dom->guest_domid, allocsz, 0, XENMEMF_address_bits(37) | XENMEMF_above_bits, &dom->p2m_host[i]);
+                if( rc != 0 )
+                    rc = xc_domain_memory_populate_physmap(
+                        dom->guest_xc, dom->guest_domid, allocsz, 0, 0, &dom->p2m_host[i]);
+            } 
+            else
+                rc = xc_domain_memory_populate_physmap(
+                        dom->guest_xc, dom->guest_domid, allocsz, 0, 0, &dom->p2m_host[i]);
+ 
         }
     }
 
diff -r 059c01d69a08 xen/common/page_alloc.c
--- a/xen/common/page_alloc.c	Thu Oct 29 14:48:28 2009 +0000
+++ b/xen/common/page_alloc.c	Mon Nov 02 15:37:42 2009 +0800
@@ -1085,9 +1085,9 @@
     struct page_info *pg = NULL;
     unsigned int bits = memflags >> _MEMF_bits, zone_hi = NR_ZONES - 1;
     unsigned int node = (uint8_t)((memflags >> _MEMF_node) - 1), dma_zone;
+    unsigned int is_limit_lo = memflags & _MEMF_above_bit;
 
     ASSERT(!in_irq());
-
     if ( (node == NUMA_NO_NODE) && (d != NULL) )
         node = domain_to_node(d);
 
@@ -1099,8 +1099,9 @@
         pg = alloc_heap_pages(dma_zone + 1, zone_hi, node, order, memflags);
 
     if ( (pg == NULL) &&
-         ((pg = alloc_heap_pages(MEMZONE_XEN + 1, zone_hi,
-                                 node, order, memflags)) == NULL) )
+         ((pg = alloc_heap_pages(is_limit_lo ? bits : (MEMZONE_XEN + 1), 
+              is_limit_lo ? min_t(unsigned int, bits_to_zone(BITS_PER_LONG+PAGE_SHIFT),NR_ZONES-1) :zone_hi, 
+                  node, order,memflags)) == NULL) )
          return NULL;
 
     if ( (d != NULL) && assign_pages(d, pg, order, memflags) )
diff -r 059c01d69a08 xen/include/public/memory.h
--- a/xen/include/public/memory.h	Thu Oct 29 14:48:28 2009 +0000
+++ b/xen/include/public/memory.h	Mon Nov 02 15:37:42 2009 +0800
@@ -52,6 +52,8 @@
 #define XENMEMF_get_node(x) ((((x) >> 8) - 1) & 0xffu)
 /* Flag to populate physmap with populate-on-demand entries */
 #define XENMEMF_populate_on_demand (1<<16)
+/* Allocate the pages above the bits */
+#define XENMEMF_above_bits (1<<7)
 #endif
 
 struct xen_memory_reservation {
diff -r 059c01d69a08 xen/include/xen/mm.h
--- a/xen/include/xen/mm.h	Thu Oct 29 14:48:28 2009 +0000
+++ b/xen/include/xen/mm.h	Mon Nov 02 15:37:42 2009 +0800
@@ -81,6 +81,7 @@
 #define _MEMF_node        8
 #define  MEMF_node(n)     ((((n)+1)&0xff)<<_MEMF_node)
 #define _MEMF_bits        24
+#define _MEMF_above_bit   (1<<7)
 #define  MEMF_bits(n)     ((n)<<_MEMF_bits)
 
 #ifdef CONFIG_PAGEALLOC_MAX_ORDER