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authorBob Moore <robert.moore@intel.com>2007-04-28 20:53:50 -0400
committerLen Brown <len.brown@intel.com>2007-04-28 20:55:06 -0400
commit79fff270026dc46634563a29b99e4034028ee919 (patch)
treeddc0f97ebc7c756cecbd824b4d0b7162f1e7cb6f /drivers/acpi/tables
parentde46c33745f5e2ad594c72f2cf5f490861b16ce1 (diff)
ACPICA: clear fields reserved before FADT r3
Linux-2.6.21 stopped booting on a P4/HT because Linux wrote the FADT.CST_CNT value to the SMI_CMD. Apparently this stumbled over some SMM instability, such as confusing SMM when invoking it from cpu1. Linux did this because even though the r2 FADT reserves the CST_CNT field, this BIOS set that field and Linux used it. Turns out that up through 2.6.20 we explicitly cleared cst_control for r2 FADTs. So here we go back to doing that, plus also clear some additional fields that are reserved until FADT r3. http://bugzilla.kernel.org/show_bug.cgi?id=8346 Signed-off-by: Bob Moore <robert.moore@intel.com> Signed-off-by: Len Brown <len.brown@intel.com>
Diffstat (limited to 'drivers/acpi/tables')
-rw-r--r--drivers/acpi/tables/tbfadt.c12
1 files changed, 12 insertions, 0 deletions
diff --git a/drivers/acpi/tables/tbfadt.c b/drivers/acpi/tables/tbfadt.c
index 807c7116e94..1db833eb241 100644
--- a/drivers/acpi/tables/tbfadt.c
+++ b/drivers/acpi/tables/tbfadt.c
@@ -347,6 +347,18 @@ static void acpi_tb_convert_fadt(void)
acpi_gbl_xpm1b_enable.space_id = acpi_gbl_FADT.xpm1a_event_block.space_id;
}
+
+ /*
+ * For ACPI 1.0 FADTs, ensure that reserved fields (which should be zero)
+ * are indeed zero. This will workaround BIOSs that inadvertently placed
+ * values in these fields.
+ */
+ if (acpi_gbl_FADT.header.revision < 3) {
+ acpi_gbl_FADT.preferred_profile = 0;
+ acpi_gbl_FADT.pstate_control = 0;
+ acpi_gbl_FADT.cst_control = 0;
+ acpi_gbl_FADT.boot_flags = 0;
+ }
}
/******************************************************************************