Dexuan Cui <decui@xxxxxxxxxxxxx> writes: >> From: Vitaly Kuznetsov <vkuznets@xxxxxxxxxx> >> Sent: Wednesday, April 8, 2020 8:47 AM >> > IMO 'freeze' in a Linux VM on Hyper-V is not really useful in practice, >> > so let's disallow the operation for both Gen-1 and Gen-2 VMs, even if >> > it's not an issue for Gen-1 VMs. >> >> Suspend-to-idle may not be very useful indeed, however, it worked before >> and I think we can just fix it. > > How can we fix Suspend-to-idle for a Gen-2 VM, in which no device can work > as wakeup devices? Note: in the case of Suspend-to-idle, now all the vmbus > devices including the synthetic keyboard/mouse are suspended completely. > > Are you suggesting hv_vmbus should distinguish Suspend-to-idle from > hibernation, and for the former hv_vmbus should not suspend the synthetic > keyboard/mouse? Yes, basically. > This should be doable but IMO this is not a very trivial > effort, and I'm trying to avoid it since IMO Suspend-to-idle is not really > useful in practice for a Linux VM on Hyper-V. :-) Well, to me it's equally (not) useful in all other cases :-) I think we should Cc: linux-pm@xxxxxxxxxxxxxxx and someone will describe a real world usecase to educate us, we'll then see if there is any Hyper-V specifics. > >> In particular, why do we need to do >> anything when we are not hibernating? > > Are you suggesting hv_vmbus should not suspend the vmbus devices at all > in the case of Suspend-to-idle? That what we were doing prior to the hibernation series, right? AFAIU suspend-to-idle is basically 'no processes are scheduled' mode but we don't really need to do anything with devices. > >> > +/* >> > + * Note: "freeze/suspend" here means "systemctl suspend". >> > + * "systemctl hibernate" is still supported. >> >> Let's not use systemd terminology in kernel, let's use the ones from >> admin-guide/pm/sleep-states.rst (Suspend-to-Idle/Standby/Suspend-to-RAM/ >> Hibernation). >> -- >> Vitaly > > Thanks! I'll use the accurate terms. > > Thanks, > -- Dexuan > -- Vitaly
