2 files changed, 32 insertions, 0 deletions

diff --git a/arch/x86/Kconfig.debug b/arch/x86/Kconfig.debug
index 7ce8e7025661..f4413c04e687 100644
--- a/arch/x86/Kconfig.debug
+++ b/arch/x86/Kconfig.debug
@@ -76,6 +76,18 @@ config DEBUG_RODATA
           data. This is recommended so that we can catch kernel bugs sooner.
           If in doubt, say "Y".
 
+config DIRECT_GBPAGES
+        bool "Enable gbpages-mapped kernel pagetables"
+        depends on DEBUG_KERNEL && EXPERIMENTAL && X86_64
+        help
+          Enable gigabyte pages support (if the CPU supports it). This can
+          improve the kernel's performance a tiny bit by reducing TLB
+          pressure.
+
+          This is experimental code.
+
+          If in doubt, say "N".
+
 config DEBUG_RODATA_TEST
         bool "Testcase for the DEBUG_RODATA feature"
         depends on DEBUG_RODATA
diff --git a/arch/x86/mm/init_64.c b/arch/x86/mm/init_64.c
index a02a14f0f324..6e7d5a42a09a 100644
--- a/arch/x86/mm/init_64.c
+++ b/arch/x86/mm/init_64.c
@@ -54,6 +54,26 @@ static unsigned long dma_reserve __initdata;
 
 DEFINE_PER_CPU(struct mmu_gather, mmu_gathers);
 
+int direct_gbpages __meminitdata
+#ifdef CONFIG_DIRECT_GBPAGES
+                                = 1
+#endif
+;
+
+static int __init parse_direct_gbpages_off(char *arg)
+{
+        direct_gbpages = 0;
+        return 0;
+}
+early_param("nogbpages", parse_direct_gbpages_off);
+
+static int __init parse_direct_gbpages_on(char *arg)
+{
+        direct_gbpages = 1;
+        return 0;
+}
+early_param("gbpages", parse_direct_gbpages_on);
+
 /*
  * NOTE: pagetable_init alloc all the fixmap pagetables contiguous on the
  * physical space so we can cache the place of the first one and move