On 11/22/2011 03:48 PM, Alon Levy wrote: > On Mon, Nov 21, 2011 at 05:26:55PM -0700, Eric Blake wrote: >> On 11/09/2011 05:05 AM, Srivatsa S. Bhat wrote: >>> (This patch is positioned to go in after the patch that exports the host >>> power management capabilities as XML, posted in [4]) >> >> I'm now reviewing that patch along with this series; if we need another >> revision, it may be easiest to merge the three patches into a single >> series and title it v6, so that they are together in one thread. >> >>> >>> This patch adds a new API to put a host to a suspended state (either >>> Suspend-to-RAM or Suspend-to-Disk) and setup a timed resume to get the >>> host back online, from within libvirt. >>> This uses the RTC wakeup mechanism to set up a timer alarm before >>> suspending the host, so that in-band resume is facilitated by the firing >>> of the RTC alarm, which wakes up the host. >> >> I'm not as familiar with S3/S4 as I would like to be - am I correct that >> RTC wakeup works for S3 (where the host is maintaining minimal power and >> can thus react to interrupts), but not S4 (where the host has flushed >> completely to disk and powers off, but resumes from the state on disk on >> next power on)? Or am I misunderstanding these two power-saving states? > > Theoretically I think you're right, but in current qemu S3 does a > hardware reset without reseting the memory, so kind of a sleep + > immediate wakeup. S4 is emulated correctly - qemu doesn't have to do > anything special. > Hi Alon, Actually this patchset talks about S3/S4 on the _host_, not the guest. So, in the host, RTC wakeup works for both S3 and S4. Thanks, Srivatsa S. Bhat IBM Linux Technology Center -- libvir-list mailing list libvir-list@xxxxxxxxxx https://www.redhat.com/mailman/listinfo/libvir-list