[Qemu-devel] What is the meaning of "Device automatic Partial to Slumber transitions"?

[Peter Teoh]

I am trying to compare the difference between hdparm running inside
qemu (as checkout from latest development git tree) and running on
native.   My /dev/sdb is an Intel SSD harddisk.

So running this:

sudo qemu-system-x86_64 -m 1024 -boot c -enable-kvm -net nic -net user \
-device virtio-scsi-pci \
-drive if=none,file=/dev/sdb,id=sdb,cache=off,format=raw \
-device scsi-block,drive=sdb \
-hda fedora_hdd.img  \
-monitor stdio -vga std

and then followed by "hdparm -I --verbose /dev/sdb" inside the qemu
guest, versus the hdparm running on the native machine, I can see that
only this entry is identified as "Unknown 76 (14)"  but whereas on the
native machine it is listed as:

        "Device automatic Partial to Slumber transitions",/* word 76 bit 14 */

Can someone explained the difference (and its meaning) in the virtio emulation?