x86, mm: relocate initrd under all mem for 64bit

instead of under 4g.

For 64bit, we can use any mapped mem instead of low mem.
Signed-off-by: Yinghai Lu <yinghai@kernel.org>
Link: http://lkml.kernel.org/r/1353123563-3103-17-git-send-email-yinghai@kernel.orgSigned-off-by: H. Peter Anvin <hpa@linux.intel.com>

arch/x86/kernel/setup.c

@@ -324,7 +324,7 @@ static void __init relocate_initrd(void)
 	char *p, *q;
 
 	/* We need to move the initrd down into directly mapped mem */
-	ramdisk_here = memblock_find_in_range(0, PFN_PHYS(max_low_pfn_mapped),
+	ramdisk_here = memblock_find_in_range(0, PFN_PHYS(max_pfn_mapped),
 						 area_size, PAGE_SIZE);
 
 	if (!ramdisk_here)
@@ -392,7 +392,7 @@ static void __init reserve_initrd(void)
 
 	initrd_start = 0;
 
-	mapped_size = get_mem_size(max_low_pfn_mapped);
+	mapped_size = get_mem_size(max_pfn_mapped);
 	if (ramdisk_size >= (mapped_size>>1))
 		panic("initrd too large to handle, "
 		       "disabling initrd (%lld needed, %lld available)\n",
@@ -401,8 +401,7 @@ static void __init reserve_initrd(void)
 	printk(KERN_INFO "RAMDISK: [mem %#010llx-%#010llx]\n", ramdisk_image,
 			ramdisk_end - 1);
 
-	if (ramdisk_end <= (max_low_pfn_mapped<<PAGE_SHIFT) &&
-	    pfn_range_is_mapped(PFN_DOWN(ramdisk_image),
+	if (pfn_range_is_mapped(PFN_DOWN(ramdisk_image),
 				PFN_DOWN(ramdisk_end))) {
 		/* All are mapped, easy case */
 		/*