Messages in this thread | | | Date | Thu, 21 Aug 2008 23:16:57 -0700 | From | "Yinghai Lu" <> | Subject | Re: [Bug 11388] New: 2.6.27-rc3 warns about MTRR range; only 3 of 16gb of memory is usable |
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On Thu, Aug 21, 2008 at 8:50 PM, Ingo Molnar <mingo@elte.hu> wrote: > > * Yinghai Lu <yhlu.kernel@gmail.com> wrote: > >> or please try attached workaround patch. hope it works. >> >> Ingo, >> if it works, we need to push it for 2.6.27 > > i've tidied up your patch (see the commit below) and have queued it up > in x86/urgent. It seems fairly safe and i guess we can push it to > v2.6.27 if Joshua reports test success. Joshua, could you give it a go > please? > > Ingo > > --------------> > From 38cc1c3df77c1bb739a4766788eb9fa49f16ffdf Mon Sep 17 00:00:00 2001 > From: Yinghai Lu <yhlu.kernel@gmail.com> > Date: Thu, 21 Aug 2008 20:24:24 -0700 > Subject: [PATCH] x86: work around MTRR mask setting > > 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 <yhlu.kernel@gmail.com> > Cc: <stable@kernel.org> > Signed-off-by: Ingo Molnar <mingo@elte.hu> > --- > arch/x86/kernel/cpu/mtrr/generic.c | 15 +++++++++++++-- > 1 files changed, 13 insertions(+), 2 deletions(-) > > diff --git a/arch/x86/kernel/cpu/mtrr/generic.c b/arch/x86/kernel/cpu/mtrr/generic.c > index 509bd3d..43102e0 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; > + /* 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");
can you change WARN_ON to WARN_ON_ONCE ?
YH
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