On Tue, Dec 22, 2020 at 04:12:22PM -0800, Dexuan Cui wrote: > 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/supported_features for this purpose. > > Signed-off-by: Dexuan Cui <decui@xxxxxxxxxxxxx> > --- > Documentation/ABI/stable/sysfs-bus-vmbus | 7 +++++++ > drivers/hv/vmbus_drv.c | 20 ++++++++++++++++++++ > 2 files changed, 27 insertions(+) > > diff --git a/Documentation/ABI/stable/sysfs-bus-vmbus b/Documentation/ABI/stable/sysfs-bus-vmbus > index c27b7b89477c..3ba765ae6695 100644 > --- a/Documentation/ABI/stable/sysfs-bus-vmbus > +++ b/Documentation/ABI/stable/sysfs-bus-vmbus > @@ -1,3 +1,10 @@ > +What: /sys/bus/vmbus/supported_features > +Date: Dec 2020 > +KernelVersion: 5.11 Too late for 5.11 now. Given this is a list of strings, do you want to enumerate them in a Values section or the Description section? Wei.
