ACPI_PM_EVT_BLK
value = inw(ACPI_PM_EVT_BLK);
outw(value, ACPI_PM_EVT_BLK);
pm_iowrite(0x20, ACPI_PM_EVT_BLK & 0xff);
pm_iowrite(0x21, ACPI_PM_EVT_BLK >> 8);