In the case of the PM1 Control Registers being distributed between two chipsets, how can I determine if the SCI_EN bit is clear or it is not present in the corresponding PM1x_CNT when his bit equals to 0?
ACPI say that I have to try to set and read back bits to determine if they are present or not, but, can I write directly to the SCI_EN reg, and will have this bad side effects?