diff options
| -rw-r--r-- | arch/x86/kernel/bugs_64.c | 12 | ||||
| -rw-r--r-- | arch/x86/mm/init_32.c | 7 |
2 files changed, 18 insertions, 1 deletions
diff --git a/arch/x86/kernel/bugs_64.c b/arch/x86/kernel/bugs_64.c index 60207e999a04..9a3ed0649d4e 100644 --- a/arch/x86/kernel/bugs_64.c +++ b/arch/x86/kernel/bugs_64.c @@ -9,6 +9,7 @@ #include <asm/bugs.h> #include <asm/processor.h> #include <asm/mtrr.h> +#include <asm/cacheflush.h> void __init check_bugs(void) { @@ -18,4 +19,15 @@ void __init check_bugs(void) print_cpu_info(&boot_cpu_data); #endif alternative_instructions(); + + /* + * Make sure the first 2MB area is not mapped by huge pages + * There are typically fixed size MTRRs in there and overlapping + * MTRRs into large pages causes slow downs. + * + * Right now we don't do that with gbpages because there seems + * very little benefit for that case. + */ + if (!direct_gbpages) + set_memory_4k((unsigned long)__va(0), 1); } diff --git a/arch/x86/mm/init_32.c b/arch/x86/mm/init_32.c index fc3ace2e88f1..1500dc8d63e4 100644 --- a/arch/x86/mm/init_32.c +++ b/arch/x86/mm/init_32.c @@ -181,8 +181,13 @@ static void __init kernel_physical_mapping_init(pgd_t *pgd_base) /* * Map with big pages if possible, otherwise * create normal page tables: + * + * Don't use a large page for the first 2/4MB of memory + * because there are often fixed size MTRRs in there + * and overlapping MTRRs into large pages can cause + * slowdowns. */ - if (cpu_has_pse) { + if (cpu_has_pse && !(pgd_idx == 0 && pmd_idx == 0)) { unsigned int addr2; pgprot_t prot = PAGE_KERNEL_LARGE; |