diff options
| -rw-r--r-- | Documentation/x86_64/boot-options.txt | 5 | ||||
| -rw-r--r-- | arch/x86/Kconfig.debug | 12 | ||||
| -rw-r--r-- | arch/x86/mm/init_64.c | 20 | ||||
| -rw-r--r-- | include/asm-x86/pgtable_64.h | 2 |
4 files changed, 39 insertions, 0 deletions
diff --git a/Documentation/x86_64/boot-options.txt b/Documentation/x86_64/boot-options.txt index 34abae4e9442..b0c7b6c4abda 100644 --- a/Documentation/x86_64/boot-options.txt +++ b/Documentation/x86_64/boot-options.txt @@ -307,3 +307,8 @@ Debugging stuck (default) Miscellaneous + + nogbpages + Do not use GB pages for kernel direct mappings. + gbpages + Use GB pages for kernel direct mappings. 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 diff --git a/include/asm-x86/pgtable_64.h b/include/asm-x86/pgtable_64.h index 01d2359e7a34..6ef09914acbe 100644 --- a/include/asm-x86/pgtable_64.h +++ b/include/asm-x86/pgtable_64.h @@ -239,6 +239,8 @@ static inline int pud_large(pud_t pte) #define update_mmu_cache(vma,address,pte) do { } while (0) +extern int direct_gbpages; + /* Encode and de-code a swap entry */ #define __swp_type(x) (((x).val >> 1) & 0x3f) #define __swp_offset(x) ((x).val >> 8) |