On Thu, Jan 07, 2021 at 06:08:51PM +0000, Michael Kelley wrote: > From: Dexuan Cui <decui@xxxxxxxxxxxxx> Sent: Wednesday, January 6, 2021 5:46 PM > > > > When a Linux VM runs on Hyper-V, if the host toolstack doesn't support > > hibernation for the VM (this happens on old Hyper-V hosts like Windows > > Server 2016, or new Hyper-V hosts if the admin or user doesn't declare > > the hibernation intent for the VM), the VM is discouraged from trying > > hibernation (because the host doesn't guarantee that the VM's virtual > > hardware configuration will remain exactly the same across hibernation), > > i.e. the VM should not try to set up the swap partition/file for > > hibernation, etc. > > > > x86 Hyper-V uses the presence of the virtual ACPI S4 state as the > > indication of the host toolstack support for a VM. Currently there is > > no easy and reliable way for the userspace to detect the presence of > > the state (see https://lkml.org/lkml/2020/12/11/1097). Add > > /sys/bus/vmbus/hibernation for this purpose. > > > > Signed-off-by: Dexuan Cui <decui@xxxxxxxxxxxxx> [...] > > Reviewed-by: Michael Kelley <mikelley@xxxxxxxxxxxxx> Queued for hyperv-next. Thanks. Wei. >
