> ---
> arch/x86/kernel/bugs_64.c | 12 ++++++++++++
> arch/x86/mm/init_32.c | 6 +++++-
> 2 files changed, 17 insertions(+), 1 deletion(-)
>
> Index: linux/arch/x86/kernel/bugs_64.c
> ===================================================================
> --- linux.orig/arch/x86/kernel/bugs_64.c
> +++ linux/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);
> }
> Index: linux/arch/x86/mm/init_32.c
> ===================================================================
> --- linux.orig/arch/x86/mm/init_32.c
> +++ linux/arch/x86/mm/init_32.c
> @@ -181,8 +181,13 @@ static void __init kernel_physical_mappi
> /*
> * 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;
>
> --
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