x86: introduce max_low_pfn_mapped for 64-bit

when more than 4g memory is installed, don't map the big hole below 4g.

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, 18 insertions, 4 deletions

diff --git a/arch/x86/kernel/setup.c b/arch/x86/kernel/setup.c
index a7c3471ea17c..86fc2d624270 100644
--- a/arch/x86/kernel/setup.c
+++ b/arch/x86/kernel/setup.c
@@ -713,14 +713,14 @@ void __init setup_arch(char **cmdline_p)
          * partially used pages are not usable - thus
          * we are rounding upwards:
          */
-        max_pfn = e820_end();
+        max_pfn = e820_end_of_ram_pfn();
 
         /* preallocate 4k for mptable mpc */
         early_reserve_e820_mpc_new();
         /* update e820 for memory not covered by WB MTRRs */
         mtrr_bp_init();
         if (mtrr_trim_uncached_memory(max_pfn))
-                max_pfn = e820_end();
+                max_pfn = e820_end_of_ram_pfn();
 
 #ifdef CONFIG_X86_32
         /* max_low_pfn get updated here */
@@ -732,12 +732,26 @@ void __init setup_arch(char **cmdline_p)
 
         /* How many end-of-memory variables you have, grandma! */
         /* need this before calling reserve_initrd */
-        max_low_pfn = max_pfn;
+        if (max_pfn > (1UL<<(32 - PAGE_SHIFT)))
+                max_low_pfn = e820_end_of_low_ram_pfn();
+        else
+                max_low_pfn = max_pfn;
+
         high_memory = (void *)__va(max_pfn * PAGE_SIZE - 1) + 1;
 #endif
 
         /* max_pfn_mapped is updated here */
-        max_pfn_mapped = init_memory_mapping(0, (max_low_pfn << PAGE_SHIFT));
+        max_low_pfn_mapped = init_memory_mapping(0, max_low_pfn<<PAGE_SHIFT);
+        max_pfn_mapped = max_low_pfn_mapped;
+
+#ifdef CONFIG_X86_64
+        if (max_pfn > max_low_pfn) {
+                max_pfn_mapped = init_memory_mapping(1UL<<32,
+                                                     max_pfn<<PAGE_SHIFT);
+                /* can we preseve max_low_pfn ?*/
+                max_low_pfn = max_pfn;
+        }
+#endif
 
         /*
          * NOTE: On x86-32, only from this point on, fixmaps are ready for use.