On Sat, Feb 5, 2022 at 2:54 AM Jan Stary <[email protected]> wrote: > This is current/amd64 on a Thinkapd T420s, dmesgs below. > It seems that C2 is or is not supported depending on > whether the machine boots on AC or on battery > (judging by three boots of each). > Is this intended? >
The acpicpu driver is reporting what ACPI told it; presumably the authors of the AML intended this change as a way to reduce power consumption. Now, ACPI provides a mechanism for the OS to tell it to notify the OS if the contents of the _CST table changes and at least in some cases acpicpu registers for that and if called it would write new acpicpu lines to the dmesg. If you're not seeing those when plugging/unplugging, there are two possibilities: * does the AML on your system actually change the values and trigger the notify? * is acpicpu actually registering the callback correctly? I would suggest adding a printf() right before the aml_register_notify() call in acpicpu.c to see if it's actually being hit, and if it is then dump the tables on your box and grovel around in them to see if you see notification support on the CPU nodes. Philip Guenther
