[PATCH 10/10] mm: Create memory regions at boot-up

[Ankita Garg <ankita@in.ibm.com>]

Memory regions are created at boot up time, from the information obtained
from the firmware. This patchset was developed on ARM platform, on which at
present u-boot bootloader does not export information about memory units that
can be independently power managed. For the purpose of demonstration, 2 hard
coded memory regions are created, of 256MB each on the Panda board with 512MB
RAM.

Signed-off-by: Ankita Garg <ankita@in.ibm.com>
---
 include/linux/mmzone.h |    8 +++-----
 mm/page_alloc.c        |   29 +++++++++++++++++++++++++++++
 2 files changed, 32 insertions(+), 5 deletions(-)

diff --git a/include/linux/mmzone.h b/include/linux/mmzone.h
index bc3e3fd..5dbe1e1 100644
--- a/include/linux/mmzone.h
+++ b/include/linux/mmzone.h
@@ -627,14 +627,12 @@ typedef struct mem_region_list_data {
  */
 struct bootmem_data;
 typedef struct pglist_data {
-/*	The linkage to node_zones is now removed. The new hierarchy introduced
- *	is pg_data_t -> mem_region -> zones
- * 	struct zone node_zones[MAX_NR_ZONES];
- */
 	struct zonelist node_zonelists[MAX_ZONELISTS];
 	int nr_zones;
 #ifdef CONFIG_FLAT_NODE_MEM_MAP	/* means !SPARSEMEM */
-	struct page *node_mem_map;
+	strs pg_data_t -> mem_region -> zones
+ *      struct zone node_zones[MAX_NR_ZONES];
+ */uct page *node_mem_map;
 #ifdef CONFIG_CGROUP_MEM_RES_CTLR
 	struct page_cgroup *node_page_cgroup;
 #endif
diff --git a/mm/page_alloc.c b/mm/page_alloc.c
index da8b045..3d994e8 100644
--- a/mm/page_alloc.c
+++ b/mm/page_alloc.c
@@ -4285,6 +4285,34 @@ static inline int pageblock_default_order(unsigned int order)
 
 #endif /* CONFIG_HUGETLB_PAGE_SIZE_VARIABLE */
 
+#define REGIONS_SIZE   (512 << 20) >> PAGE_SHIFT
+
+static void init_node_memory_regions(struct pglist_data *pgdat)
+{
+	int cnt = 0;
+	unsigned long i;
+	unsigned long start_pfn = pgdat->node_start_pfn;
+	unsigned long spanned_pages = pgdat->node_spanned_pages;
+	unsigned long total = 0;
+
+	for (i = start_pfn; i < start_pfn + spanned_pages; i+= REGIONS_SIZE) {
+		mem_region_t *mem_region = &pgdat->mem_regions[cnt];
+
+		mem_region->start_pfn = i;
+		if ((spanned_pages - total) <= REGIONS_SIZE) {
+			mem_region->spanned_pages = spanned_pages - total;
+		}
+		else
+			mem_region->spanned_pages = REGIONS_SIZE;
+
+		mem_region->node = pgdat->node_id;
+		mem_region->region = cnt;
+		pgdat->nr_mem_regions++;
+		total += mem_region->spanned_pages;
+		cnt++;
+	}
+}
+
 /*
  * Set up the zone data structures:
  *   - mark all pages reserved
@@ -4447,6 +4475,7 @@ void __paginginit free_area_init_node(int nid, unsigned long *zones_size,
 		(unsigned long)pgdat->node_mem_map);
 #endif
 
+	init_node_memory_regions(pgdat);
 	free_area_init_core(pgdat, zones_size, zholes_size);
 }
 
-- 
1.7.4

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