On Friday, 22 of February 2008, Mark Lord wrote:Rafael J. Wysocki wrote:On Friday, 22 of February 2008, Mark Lord wrote:..david@xxxxxxx wrote:
..
I've been watching for kexec hibernate for a little while now, and the..
last I saw was that acpi was incompatible with the kexec hibernate (but
the suspend folks were still claiming that devices needed to be put in
the 'right mode' not just powered off. I've been waiting to see this
resolved.
Yeah, exactly. What's so special about poweroff on hibernation?
Why even bother with the special "S4" state there?
(1) To be able to wake up with the help of devices that can't wake
the system up from S5 (power off)
(2) To handle some platform devices appropriately over the cycle
That's the theory. I've read about it, but have yet to imagine
any real-life situation where it applies.
But this isn't my speciality, so.. do you have experience with any real examples?
Yup. The fan in my notebook behaves incorrectly after a resume from
hibernation if S5 is entered instead of S4 during it.
I don't know why exactly it happens, but that's how it goes.
Also, some machines are reported to behave incorrectly after a "shutdown"
mode hibernation, while the same machines work just fine after a "platform"
mode hibernation. So at least for these machines it seems to matter.