2.6.25-stable review patch. If anyone has any objections, please let us know. ------------------ From: Yinghai Lu commit 38cc1c3df77c1bb739a4766788eb9fa49f16ffdf upstream Joshua Hoblitt reported that only 3 GB of his 16 GB of RAM is usable. Booting with mtrr_show showed us the BIOS-initialized MTRR settings - which are all wrong. So the root cause is that the BIOS has not set the mask correctly: > [ 0.429971] MSR00000200: 00000000d0000000 > [ 0.433305] MSR00000201: 0000000ff0000800 > should be ==> [ 0.433305] MSR00000201: 0000003ff0000800 > > [ 0.436638] MSR00000202: 00000000e0000000 > [ 0.439971] MSR00000203: 0000000fe0000800 > should be ==> [ 0.439971] MSR00000203: 0000003fe0000800 > > [ 0.443304] MSR00000204: 0000000000000006 > [ 0.446637] MSR00000205: 0000000c00000800 > should be ==> [ 0.446637] MSR00000205: 0000003c00000800 > > [ 0.449970] MSR00000206: 0000000400000006 > [ 0.453303] MSR00000207: 0000000fe0000800 > should be ==> [ 0.453303] MSR00000207: 0000003fe0000800 > > [ 0.456636] MSR00000208: 0000000420000006 > [ 0.459970] MSR00000209: 0000000ff0000800 > should be ==> [ 0.459970] MSR00000209: 0000003ff0000800 So detect this borkage and add the prefix 111. Signed-off-by: Yinghai Lu Signed-off-by: Ingo Molnar Signed-off-by: Greg Kroah-Hartman --- arch/x86/kernel/cpu/mtrr/generic.c | 15 +++++++++++++-- 1 file changed, 13 insertions(+), 2 deletions(-) --- a/arch/x86/kernel/cpu/mtrr/generic.c +++ b/arch/x86/kernel/cpu/mtrr/generic.c @@ -229,6 +229,7 @@ static void generic_get_mtrr(unsigned in 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) { @@ -242,8 +243,18 @@ static void generic_get_mtrr(unsigned in 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; + /* Expand tmp with high bits to all 1s*/ + hi = fls(tmp); + if (hi > 0) { + tmp |= ~((1<<(hi - 1)) - 1); + + if (tmp != mask_lo) { + WARN_ON("mtrr: your BIOS has set up an incorrect mask, fixing it up.\n"); + mask_lo = tmp; + } + } /* This works correctly if size is a power of two, i.e. a contiguous range. */ -- -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/