From: Bob Moore <robert.moore@xxxxxxxxx> 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@xxxxxxxxx> Signed-off-by: Len Brown <len.brown@xxxxxxxxx> --- drivers/acpi/tables/tbfadt.c | 12 ++++++++++++ 1 files changed, 12 insertions(+), 0 deletions(-) diff --git a/drivers/acpi/tables/tbfadt.c b/drivers/acpi/tables/tbfadt.c index 807c711..1db833e 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; + } } /****************************************************************************** -- 1.5.2.rc0.34.gda94 - To unsubscribe from this list: send the line "unsubscribe linux-acpi" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
