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x86: MTRR workaround for system with stange var MTRRs

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Impact: don't trim e820 according to wrong mtrr

Ozan reports that his server emits strange warning.
it turns out the BIOS sets the MTRRs incorrectly.

Ignore those strange ranges, and don't trim e820,
just emit one warning about BIOS

Reported-by: Ozan Çağlayan <ozan@pardus.org.tr>
Signed-off-by: Yinghai Lu <yinghai@kernel.org>
LKML-Reference: <49BEE1E7.7020706@kernel.org>
Signed-off-by: Ingo Molnar <mingo@elte.hu>
This commit is contained in:
Yinghai Lu
2009-03-16 16:33:59 -07:00
committed by Ingo Molnar
parent d4c90e37a2
commit f0348c438c
3 changed files with 20 additions and 8 deletions
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11
arch/x86/kernel/cpu/mtrr/cleanup.c
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@@ -189,6 +189,17 @@ x86_get_mtrr_mem_range(struct res_range *range, int nr_range,
if (!size)
continue;
base = range_state[i].base_pfn;
if (base < (1<<(20-PAGE_SHIFT)) && mtrr_state.have_fixed &&
(mtrr_state.enabled & 1)) {
/* Var MTRR contains UC entry below 1M? Skip it: */
printk(KERN_WARNING "WARNING: BIOS bug: VAR MTRR %d "
"contains strange UC entry under 1M, check "
"with your system vendor!\n", i);
if (base + size <= (1<<(20-PAGE_SHIFT)))
continue;
size -= (1<<(20-PAGE_SHIFT)) - base;
base = 1<<(20-PAGE_SHIFT);
}
subtract_range(range, base, base + size - 1);
}
if (extra_remove_size)