> From: Pavel Machek <pavel@xxxxxx> > Sent: Monday, December 21, 2020 11:08 AM > > On Sat 2020-12-12 01:20:30, Dexuan Cui wrote: > > Hi all, > > It looks like Linux can hibernate even if the system does not support the ACPI > > S4 state, as long as the system can shut down, so "cat /sys/power/state" > > always contains "disk", unless we specify the kernel parameter "nohibernate" > > or we use LOCKDOWN_HIBERNATION. > > > > In some scenarios IMO it can still be useful if the userspace is able to detect > > if the ACPI S4 state is supported or not, e.g. when a Linux guest runs on > > Hyper-V, Hyper-V uses the virtual ACPI S4 state as an indicator of the proper > > support of the tool stack on the host, i.e. the guest is discouraged from > > trying hibernation if the state is not supported. > > Umm. Does not sound like exactly strong reason to me. Hi Pavel, Thanks for the reply. I realized that it may be better for me to add the code to Hyper-V specific driver: https://lkml.org/lkml/2020/12/22/719 Let's see how it goes that way. :-) Thanks, Dexuan
