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    SubjectRe: [Bug 11388] New: 2.6.27-rc3 warns about MTRR range; only 3 of 16gb of memory is usable
    On Thu, Aug 21, 2008 at 7:26 PM, Yinghai Lu <yhlu.kernel@gmail.com> wrote:
    > On Thu, Aug 21, 2008 at 7:15 PM, Joshua Hoblitt <josh@hoblitt.com> wrote:
    >> On Thu, Aug 21, 2008 at 06:55:58PM -0700, Yinghai Lu wrote:
    >> address sizes : 38 bits physical, 48 bits virtual
    >
    > good, the root cause is your bios not set mask correctly...
    >
    > it should set var mtrr like
    >
    > [ 0.429971] MSR00000200: 00000000d0000000
    > [ 0.433305] MSR00000201: 0000000ff0000800
    > ==> [ 0.433305] MSR00000201: 0000003ff0000800
    >
    > [ 0.436638] MSR00000202: 00000000e0000000
    > [ 0.439971] MSR00000203: 0000000fe0000800
    > ==> [ 0.439971] MSR00000203: 0000003fe0000800
    >
    > [ 0.443304] MSR00000204: 0000000000000006
    > [ 0.446637] MSR00000205: 0000000c00000800
    > ==> [ 0.446637] MSR00000205: 0000003c00000800
    >
    > [ 0.449970] MSR00000206: 0000000400000006
    > [ 0.453303] MSR00000207: 0000000fe0000800
    > ==>[ 0.453303] MSR00000207: 0000003fe0000800
    >
    > [ 0.456636] MSR00000208: 0000000420000006
    > [ 0.459970] MSR00000209: 0000000ff0000800
    > ==> [ 0.459970] MSR00000209: 0000003ff0000800
    >
    > you may talk to your BIOS vendor or system vendor to request one new
    > updated BIOS.
    >

    or please try attached workaround patch. hope it works.

    Ingo,
    if it works, we need to push it for 2.6.27

    YH
    [PATCH] x86: workaroun mtrr mask setting

    Some BIOS doesn't set mtrr mask correctly, workaround it be prefix 111

    Signed-off-by: Yinghai Lu <yhlu.kernel@gmail.com>

    diff --git a/arch/x86/kernel/cpu/mtrr/generic.c b/arch/x86/kernel/cpu/mtrr/generic.c
    index 509bd3d..a17d5ba 100644
    --- a/arch/x86/kernel/cpu/mtrr/generic.c
    +++ b/arch/x86/kernel/cpu/mtrr/generic.c
    @@ -379,6 +379,7 @@ static void generic_get_mtrr(unsigned int reg, unsigned long *base,
    unsigned long *size, mtrr_type *type)
    {
    unsigned int mask_lo, mask_hi, base_lo, base_hi;
    + unsigned int tmp, hi;

    rdmsr(MTRRphysMask_MSR(reg), mask_lo, mask_hi);
    if ((mask_lo & 0x800) == 0) {
    @@ -392,8 +393,18 @@ static void generic_get_mtrr(unsigned int reg, unsigned long *base,
    rdmsr(MTRRphysBase_MSR(reg), base_lo, base_hi);

    /* Work out the shifted address mask. */
    - mask_lo = size_or_mask | mask_hi << (32 - PAGE_SHIFT)
    - | mask_lo >> PAGE_SHIFT;
    + tmp = mask_hi << (32 - PAGE_SHIFT) | mask_lo >> PAGE_SHIFT;
    + mask_lo = size_or_mask | tmp;
    + /* expend tmp with high bits to all 1s*/
    + hi = fls(tmp);
    + if (hi > 0) {
    + tmp |= ~((1<<(hi - 1)) - 1);
    +
    + if (tmp != mask_lo) {
    + WARN_ON("You BIOS mask set is wrong, complain to vendor\n");
    + mask_lo = tmp;
    + }
    + }

    /* This works correctly if size is a power of two, i.e. a
    contiguous range. */
    \
     
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      Last update: 2008-08-22 05:27    [W:0.030 / U:0.512 seconds]
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