#ifdef CONFIG_X86_64
        if (max_pfn > max_low_pfn) {
                int i;
-               for (i = 0; i < e820.nr_map; i++) {
-                       struct e820entry *ei = &e820.map[i];
+               unsigned long start, end;
+               unsigned long start_pfn, end_pfn;
 
-                       if (ei->addr + ei->size <= 1UL << 32)
-                               continue;
+               for_each_mem_pfn_range(i, MAX_NUMNODES, &start_pfn, &end_pfn,
+                                                        NULL) {
 
-                       if (ei->type == E820_RESERVED)
+                       end = PFN_PHYS(end_pfn);
+                       if (end <= (1UL<<32))
                                continue;
 
+                       start = PFN_PHYS(start_pfn);
                        max_pfn_mapped = init_memory_mapping(
-                               ei->addr < 1UL << 32 ? 1UL << 32 : ei->addr,
-                               ei->addr + ei->size);
+                                               max((1UL<<32), start), end);
                }
 
                /* can we preseve max_low_pfn ?*/