1 files changed, 85 insertions, 0 deletions

diff --git a/mm/sparse.c b/mm/sparse.c
new file mode 100644
index 000000000000..f888385b9e14
--- /dev/null
+++ b/mm/sparse.c
@@ -0,0 +1,85 @@
+/*
+ * sparse memory mappings.
+ */
+#include <linux/config.h>
+#include <linux/mm.h>
+#include <linux/mmzone.h>
+#include <linux/bootmem.h>
+#include <linux/module.h>
+#include <asm/dma.h>
+
+/*
+ * Permanent SPARSEMEM data:
+ *
+ * 1) mem_section       - memory sections, mem_map's for valid memory
+ */
+struct mem_section mem_section[NR_MEM_SECTIONS];
+EXPORT_SYMBOL(mem_section);
+
+/* Record a memory area against a node. */
+void memory_present(int nid, unsigned long start, unsigned long end)
+{
+        unsigned long pfn;
+
+        start &= PAGE_SECTION_MASK;
+        for (pfn = start; pfn < end; pfn += PAGES_PER_SECTION) {
+                unsigned long section = pfn_to_section_nr(pfn);
+                if (!mem_section[section].section_mem_map)
+                        mem_section[section].section_mem_map = (void *) -1;
+        }
+}
+
+/*
+ * Only used by the i386 NUMA architecures, but relatively
+ * generic code.
+ */
+unsigned long __init node_memmap_size_bytes(int nid, unsigned long start_pfn,
+                                                     unsigned long end_pfn)
+{
+        unsigned long pfn;
+        unsigned long nr_pages = 0;
+
+        for (pfn = start_pfn; pfn < end_pfn; pfn += PAGES_PER_SECTION) {
+                if (nid != early_pfn_to_nid(pfn))
+                        continue;
+
+                if (pfn_valid(pfn))
+                        nr_pages += PAGES_PER_SECTION;
+        }
+
+        return nr_pages * sizeof(struct page);
+}
+
+/*
+ * Allocate the accumulated non-linear sections, allocate a mem_map
+ * for each and record the physical to section mapping.
+ */
+void sparse_init(void)
+{
+        unsigned long pnum;
+        struct page *map;
+        int nid;
+
+        for (pnum = 0; pnum < NR_MEM_SECTIONS; pnum++) {
+                if (!mem_section[pnum].section_mem_map)
+                        continue;
+
+                nid = early_pfn_to_nid(section_nr_to_pfn(pnum));
+                map = alloc_remap(nid, sizeof(struct page) * PAGES_PER_SECTION);
+                if (!map)
+                        map = alloc_bootmem_node(NODE_DATA(nid),
+                                sizeof(struct page) * PAGES_PER_SECTION);
+                if (!map) {
+                        mem_section[pnum].section_mem_map = 0;
+                        continue;
+                }
+
+                /*
+                 * Subtle, we encode the real pfn into the mem_map such that
+                 * the identity pfn - section_mem_map will return the actual
+                 * physical page frame number.
+                 */
+                mem_section[pnum].section_mem_map = map -
+                                                section_nr_to_pfn(pnum);
+        }
+}