x86: max_low_pfn_mapped fix, #3

optimization: try to merge the range with same page size in
init_memory_mapping, to get the best possible linear mappings set up.

thus when GBpages is not there, we could do 2M pages.

Signed-off-by: Yinghai Lu <yhlu.kernel@gmail.com>
Cc: Suresh Siddha <suresh.b.siddha@intel.com>
Signed-off-by: Ingo Molnar <mingo@elte.hu>

1 files changed, 14 insertions, 0 deletions

diff --git a/arch/x86/mm/init_64.c b/arch/x86/mm/init_64.c
index 122bcef222f..a25cc6fa220 100644
--- a/arch/x86/mm/init_64.c
+++ b/arch/x86/mm/init_64.c
@@ -763,6 +763,20 @@ unsigned long __init_refok init_memory_mapping(unsigned long start,
         end_pfn = end>>PAGE_SHIFT;
         nr_range = save_mr(mr, nr_range, start_pfn, end_pfn, 0);
 
+        /* try to merge same page size and continuous */
+        for (i = 0; nr_range > 1 && i < nr_range - 1; i++) {
+                unsigned long old_start;
+                if (mr[i].end != mr[i+1].start ||
+                    mr[i].page_size_mask != mr[i+1].page_size_mask)
+                        continue;
+                /* move it */
+                old_start = mr[i].start;
+                memmove(&mr[i], &mr[i+1],
+                         (nr_range - 1 - i) * sizeof (struct map_range));
+                mr[i].start = old_start;
+                nr_range--;
+        }
+
         for (i = 0; i < nr_range; i++)
                 printk(KERN_DEBUG " %010lx - %010lx page %s\n",
                                 mr[i].start, mr[i].end,