Re: [linux-pm] Re: Hibernation considerations

[Alan Stern]

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

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