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-rw-r--r--arch/i386/kernel/acpi/boot.c7
1 files changed, 7 insertions, 0 deletions
diff --git a/arch/i386/kernel/acpi/boot.c b/arch/i386/kernel/acpi/boot.c
index 76b1135d401..447fa9e33ff 100644
--- a/arch/i386/kernel/acpi/boot.c
+++ b/arch/i386/kernel/acpi/boot.c
@@ -638,6 +638,13 @@ static int __init acpi_parse_fadt(unsigned long phys, unsigned long size)
return 0;
pmtmr_ioport = fadt->xpm_tmr_blk.address;
+ /*
+ * "X" fields are optional extensions to the original V1.0
+ * fields, so we must selectively expand V1.0 fields if the
+ * corresponding X field is zero.
+ */
+ if (!pmtmr_ioport)
+ pmtmr_ioport = fadt->V1_pm_tmr_blk;
} else {
/* FADT rev. 1 */
pmtmr_ioport = fadt->V1_pm_tmr_blk;