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);
+	}
+}