1 files changed, 109 insertions, 0 deletions

diff --git a/arch/x86/kernel/e820.c b/arch/x86/kernel/e820.c
index cd2b99e27d4..c140f731743 100644
--- a/arch/x86/kernel/e820.c
+++ b/arch/x86/kernel/e820.c
@@ -764,3 +764,112 @@ u64 __init early_reserve_e820(u64 startt, u64 sizet, u64 align)
         return addr;
 }
 
+#ifdef CONFIG_X86_32
+# ifdef CONFIG_X86_PAE
+#  define MAX_ARCH_PFN          (1ULL<<(36-PAGE_SHIFT))
+# else
+#  define MAX_ARCH_PFN          (1ULL<<(32-PAGE_SHIFT))
+# endif
+#else /* CONFIG_X86_32 */
+# define MAX_ARCH_PFN MAXMEM<<PAGE_SHIFT
+#endif
+
+/*
+ * Last pfn which the user wants to use.
+ */
+unsigned long __initdata end_user_pfn = MAX_ARCH_PFN;
+
+/*
+ * Find the highest page frame number we have available
+ */
+unsigned long __init e820_end_of_ram(void)
+{
+        unsigned long last_pfn;
+        unsigned long max_arch_pfn = MAX_ARCH_PFN;
+
+        last_pfn = find_max_pfn_with_active_regions();
+
+        if (last_pfn > max_arch_pfn)
+                last_pfn = max_arch_pfn;
+        if (last_pfn > end_user_pfn)
+                last_pfn = end_user_pfn;
+
+        printk(KERN_INFO "last_pfn = %lu max_arch_pfn = %lu\n",
+                         last_pfn, max_arch_pfn);
+        return last_pfn;
+}
+
+/*
+ * Finds an active region in the address range from start_pfn to last_pfn and
+ * returns its range in ei_startpfn and ei_endpfn for the e820 entry.
+ */
+int __init e820_find_active_region(const struct e820entry *ei,
+                                  unsigned long start_pfn,
+                                  unsigned long last_pfn,
+                                  unsigned long *ei_startpfn,
+                                  unsigned long *ei_endpfn)
+{
+        u64 align = PAGE_SIZE;
+
+        *ei_startpfn = round_up(ei->addr, align) >> PAGE_SHIFT;
+        *ei_endpfn = round_down(ei->addr + ei->size, align) >> PAGE_SHIFT;
+
+        /* Skip map entries smaller than a page */
+        if (*ei_startpfn >= *ei_endpfn)
+                return 0;
+
+        /* Skip if map is outside the node */
+        if (ei->type != E820_RAM || *ei_endpfn <= start_pfn ||
+                                    *ei_startpfn >= last_pfn)
+                return 0;
+
+        /* Check for overlaps */
+        if (*ei_startpfn < start_pfn)
+                *ei_startpfn = start_pfn;
+        if (*ei_endpfn > last_pfn)
+                *ei_endpfn = last_pfn;
+
+        /* Obey end_user_pfn to save on memmap */
+        if (*ei_startpfn >= end_user_pfn)
+                return 0;
+        if (*ei_endpfn > end_user_pfn)
+                *ei_endpfn = end_user_pfn;
+
+        return 1;
+}
+
+/* Walk the e820 map and register active regions within a node */
+void __init e820_register_active_regions(int nid, unsigned long start_pfn,
+                                         unsigned long last_pfn)
+{
+        unsigned long ei_startpfn;
+        unsigned long ei_endpfn;
+        int i;
+
+        for (i = 0; i < e820.nr_map; i++)
+                if (e820_find_active_region(&e820.map[i],
+                                            start_pfn, last_pfn,
+                                            &ei_startpfn, &ei_endpfn))
+                        add_active_range(nid, ei_startpfn, ei_endpfn);
+}
+
+/*
+ * Find the hole size (in bytes) in the memory range.
+ * @start: starting address of the memory range to scan
+ * @end: ending address of the memory range to scan
+ */
+u64 __init e820_hole_size(u64 start, u64 end)
+{
+        unsigned long start_pfn = start >> PAGE_SHIFT;
+        unsigned long last_pfn = end >> PAGE_SHIFT;
+        unsigned long ei_startpfn, ei_endpfn, ram = 0;
+        int i;
+
+        for (i = 0; i < e820.nr_map; i++) {
+                if (e820_find_active_region(&e820.map[i],
+                                            start_pfn, last_pfn,
+                                            &ei_startpfn, &ei_endpfn))
+                        ram += ei_endpfn - ei_startpfn;
+        }
+        return end - start - ((u64)ram << PAGE_SHIFT);
+}