Re: [patch 2/4] x86: PAT followup - Remove KERNPG_TABLE from pte entry

Mika Penttilä
2008-01-16T08:45:01Z

venkatesh.pallipadi@intel.com kirjoitti:
> KERNPG_TABLE was a bug in earlier patch. Remove it from pte.
> pte_val() check is redundant as this routine is called immediately after a
> ptepage is allocated afresh.
>
> Signed-off-by: Venkatesh Pallipadi <venkatesh.pallipadi@intel.com>
> Signed-off-by: Suresh Siddha <suresh.b.siddha@intel.com>
>
> Index: linux-2.6.git/arch/x86/mm/init_64.c
> ===================================================================
> --- linux-2.6.git.orig/arch/x86/mm/init_64.c 2008-01-15 11:02:23.000000000 -0800
> +++ linux-2.6.git/arch/x86/mm/init_64.c 2008-01-15 11:06:37.000000000 -0800
> @@ -541,9 +541,6 @@
> if (address >= end)
> break;
>
> - if (pte_val(*pte))
> - continue;
> -
> /* Nothing to map. Map the null page */
> if (!(address & (~PAGE_MASK)) &&
> (address + PAGE_SIZE <= end) &&
> @@ -561,9 +558,9 @@
> }
>
> if (exec)
> - entry = _PAGE_NX|_KERNPG_TABLE|_PAGE_GLOBAL|address;
> + entry = _PAGE_NX|_PAGE_GLOBAL|address;
> else
> - entry = _KERNPG_TABLE|_PAGE_GLOBAL|address;
> + entry = _PAGE_GLOBAL|address;
> entry &= __supported_pte_mask;
> set_pte(pte, __pte(entry));
> }
>
>

Hmm then what's the point of mapping not present 4k pages for valid mem
here?

--Mika