X-Git-Url: http://drtracing.org/?a=blobdiff_plain;f=arch%2Fx86%2Fmm%2Finit_64.c;h=b92591fa89706357942ea0388d941f6afe890218;hb=982792c782ef;hp=f35c66c5959ac0042fbf9ff43a76cf55f89d9d0f;hpb=c46a7c817e662a820373bb76b88d0ad67d6abe5d;p=deliverable%2Flinux.git

diff --git a/arch/x86/mm/init_64.c b/arch/x86/mm/init_64.c
index f35c66c5959a..b92591fa8970 100644
--- a/arch/x86/mm/init_64.c
+++ b/arch/x86/mm/init_64.c
@@ -1230,17 +1230,43 @@ const char *arch_vma_name(struct vm_area_struct *vma)
 	return NULL;
 }
 
-#ifdef CONFIG_X86_UV
-unsigned long memory_block_size_bytes(void)
+static unsigned long probe_memory_block_size(void)
 {
+	/* start from 2g */
+	unsigned long bz = 1UL<<31;
+
+#ifdef CONFIG_X86_UV
 	if (is_uv_system()) {
 		printk(KERN_INFO "UV: memory block size 2GB\n");
 		return 2UL * 1024 * 1024 * 1024;
 	}
-	return MIN_MEMORY_BLOCK_SIZE;
-}
 #endif
 
+	/* less than 64g installed */
+	if ((max_pfn << PAGE_SHIFT) < (16UL << 32))
+		return MIN_MEMORY_BLOCK_SIZE;
+
+	/* get the tail size */
+	while (bz > MIN_MEMORY_BLOCK_SIZE) {
+		if (!((max_pfn << PAGE_SHIFT) & (bz - 1)))
+			break;
+		bz >>= 1;
+	}
+
+	printk(KERN_DEBUG "memory block size : %ldMB\n", bz >> 20);
+
+	return bz;
+}
+
+static unsigned long memory_block_size_probed;
+unsigned long memory_block_size_bytes(void)
+{
+	if (!memory_block_size_probed)
+		memory_block_size_probed = probe_memory_block_size();
+
+	return memory_block_size_probed;
+}
+
 #ifdef CONFIG_SPARSEMEM_VMEMMAP
 /*
  * Initialise the sparsemem vmemmap using huge-pages at the PMD level.