Re: [linux-pm] Re: Hibernation considerations

Alan Stern
2007-07-20T16:34:57Z

On Fri, 20 Jul 2007, Milton Miller wrote:

> > We can't do this unless we have frozen tasks (this way, or another)
> > before
> > carrying out the entire operation.
>
> What can't we do? We've already worked with the drivers to quesce the
> hardware and put any information to resume the device in ram. Now we
> ask them to put their device in low power mode so we can go to sleep.
> Even if we schedule, the only thing userspace could touch is memory.

Userspace can submit I/O requests. Someone will have to audit every
driver to make sure that such I/O requests don't cause a quiesced
device to become active. If the device is active, it will make the
memory snapshot inconsistent with the on-device data.

Alan Stern