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    Subject[tip:core/memblock] x86-64: Only set max_pfn_mapped to 512 MiB if we enter via head_64.S
    Commit-ID:  859ee4f57fb4e91de8439496f62eb996f4a28ca8
    Gitweb: http://git.kernel.org/tip/859ee4f57fb4e91de8439496f62eb996f4a28ca8
    Author: Jeremy Fitzhardinge <jeremy@goop.org>
    AuthorDate: Wed, 13 Oct 2010 16:34:15 -0700
    Committer: H. Peter Anvin <hpa@linux.intel.com>
    CommitDate: Wed, 13 Oct 2010 17:09:59 -0700

    x86-64: Only set max_pfn_mapped to 512 MiB if we enter via head_64.S

    head_64.S maps up to 512 MiB, but that is not necessarity true for
    other entry paths, such as Xen.

    Thus, co-locate the setting of max_pfn_mapped with the code to
    actually set up the page tables in head_64.S. The 32-bit code is
    already so co-located. (The Xen code already sets max_pfn_mapped
    correctly for its own use case.)

    Signed-off-by: Jeremy Fitzhardinge <jeremy.fitzhardinge@citrix.com>
    LKML-Reference: <4CB641F7.9040103@goop.org>
    Signed-off-by: H. Peter Anvin <hpa@linux.intel.com>
    ---
    arch/x86/kernel/head_64.S | 2 ++
    arch/x86/kernel/setup.c | 1 -
    2 files changed, 2 insertions(+), 1 deletions(-)

    diff --git a/arch/x86/kernel/head_64.S b/arch/x86/kernel/head_64.S
    index 239046b..b75c6f4 100644
    --- a/arch/x86/kernel/head_64.S
    +++ b/arch/x86/kernel/head_64.S
    @@ -141,6 +141,8 @@ ident_complete:
    addq %rbp, trampoline_level4_pgt + (511*8)(%rip)
    #endif

    + movq $KERNEL_IMAGE_SIZE / PAGE_SIZE, max_pfn_mapped(%rip)
    +
    /* Due to ENTRY(), sometimes the empty space gets filled with
    * zeros. Better take a jmp than relying on empty space being
    * filled with 0x90 (nop)
    diff --git a/arch/x86/kernel/setup.c b/arch/x86/kernel/setup.c
    index b11a238..c3cebfe 100644
    --- a/arch/x86/kernel/setup.c
    +++ b/arch/x86/kernel/setup.c
    @@ -932,7 +932,6 @@ void __init setup_arch(char **cmdline_p)
    max_low_pfn = max_pfn;

    high_memory = (void *)__va(max_pfn * PAGE_SIZE - 1) + 1;
    - max_pfn_mapped = KERNEL_IMAGE_SIZE >> PAGE_SHIFT;
    #endif

    /*

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